Belt drive Brompton G Line folding bike upgrade kits have finally arrived! This is thanks to Kinetics, a Scottish bike shop and custom bicycle fabricator. I’ve previously covered this shop’s custom Brompton work in a video and written article.
The Brompton G Line is an all-new folding bike with bigger 20” wheels and the widest handlebars and tyres of any Brompton before it.
The Brompton G Line has been designed to ride like a typical bike across varied terrain, thanks to a more stable frame geometry and modern features such wide tyres, hydraulic disc brakes and an 8-speed internal gear hub.
This is in contrast to a typical 16″ Brompton, which is a short-distance bike that folds into a tiny form suitable for busy public transport.
Kinetics has now developed various upgrade kits for the Brompton G Line. They offer belt drive upgrade kits, as well as special dropouts that allow you to fit the ultimate internal gear hub – the Rohloff Speedhub, which has 14 gears and a 526% gear range.
Let’s start with a quick overview of the benefits of belt drive bicycles.
Benefits of Belt Drive Brompton Bikes
Belt drive folding bicycles mean you never have to clean or lubricate a chain. This keeps your bike clean, and you’ll never get grease on your hands or pants again.
Belts are typically longer-lasting than chains too. Most cyclists go years without needing to replace a belt or sprocket – expect to ride three to four times further with a belt than with a chain.
Belts are also great in adverse conditions. This is partly due to the sprocket design, which effectively sheds debris from its surfaces. In addition, a belt drivetrain is usually paired with an internal gear hub, which also helps to seal away your critical gear components from the elements.
Ultimately, belts save you a lot of time. You will spend less time maintaining your bike, sourcing replacement parts, or dropping your bike at the shop for repair.
You can read more about why I think belts are better than chains HERE.
Brompton Frame Modification
It’s scary to cut your frame in half, but it’s necessary if you’d like a belt drive Brompton.
The Kinetics G Line belt drive kit is simple to fit, however, it will require permanent frame modification. This will void your frame warranty.
As a bicycle belt is one piece (it cannot be split in two), cutting your rear dropout is necessary. Kinetics uses an angle grinder with a 1mm cutting disc to make this modification, but customers also use a hacksaw or a Dremel with a cutting disc. Now, the belt can be squeezed through the gap.
The dropout is reinforced with a stainless steel “joining plate” that connects the two dropout mounts with the rear rack mount. This plate can be seen in the image below.
Customers should apply touch-up paint over the cut to prevent surface corrosion. This corrosion would only be cosmetic, but it is best avoided.
Belt Drive Brompton Tensioner
This modified belt tensioner keeps the belt on at all times.
Kinetics has also created a special belt tensioner for the Brompton G Line.
The smooth “snubber roller” pushes the belt firmly onto the rear sprocket to prevent skipping. It can be adjusted up and down to ensure the belt stays in place.
A second “tensioner sprocket” has been printed with the Gates Centertrack design. This sprocket keeps the belt tracking straight and features side plates to guarantee the belt will not fall off when the bike is folded.
If you need to remove the rear wheel for a puncture, it’s similar to chain drive. You can half-fold the Brompton, unhook the tensioner, and remove the belt from the front sprocket to remove the rear wheel. The big advantage is that you’ll never get grease on your hands.
Brompton G Line Joining Plates & Dropouts
The stainless steel joining plates reinforce the frame and act as the rear wheel dropouts too.
Unique stainless steel joining plates and dropouts have been developed by Kinetics too. These are different for Alfine and Rohloff hub owners.
The belt tensioner goes on the inside of the frame for the Alfine hub, and the joining plate mounts to the outside. A 5mm bolt connects the joining plate to the rack mount for extra reinforcement.
The belt tensioner mounts on the outside of the frame for the Rohloff hub, and the joining plate goes on the inside. The Rohloff rear sprockets sit further out than the Alfine rear sprockets, which requires the tensioner to match the belt alignment.
A great thing is that Kinetics also offers a Rohloff OEM dropout to suit the Rohloff OEM axleplate. This makes wheel installation and removal very easy with Rohloff hubs.
Belt Drive Brompton Gearing
This belt drive Brompton has been equipped with a Rohloff 14-speed hub.
A front belt sprocket replaces the front chain sprocket. The 60-tooth front belt sprocket can be used with 22 and 24-tooth rear sprockets on the standard Shimano Alfine hub to provide gear ratios similar to the standard Brompton G Line gearing (54-20T or 50-20T).
The gear ratios are much lower when you upgrade to the Rohloff 14-speed hub. With a 63-tooth front sprocket and 19-tooth rear sprocket, the low climbing gear is under 20 gear inches (~1.55 development). This is similar to the climbing gear you’d find on a mountain bike!
Belt Drive Brompton Upgrade Kit Pricing
The belt drive Brompton upgrade kits cost £395.
This isn’t cheap but includes the full belt drivetrain (~£270 by itself) along with the special components required to make a belt drive Brompton G Line. Kinetics is happy to modify your frame and fit the kit if you live in the region.
SternShift brings the convenience of electric shifting to bikes with a Rohloff 14-speed hub.
For those who aren’t aware, the Rohloff Speedhub 500/14 is an internally geared rear hub that has been servicing the demands of bike travellers for a few decades now. Inside the oversized hub shell are 14 gears that offer a wider gear range than most derailleur drivetrains.
The gears all sit inside an oil bath that’s sealed away from the elements. These hubs work great when the riding conditions are good and evenbetter when they are not!
Rohloff hubs are especially popular amongst bike travellers and commuters who ride year-round. This is because they are very low-maintenance (especially when combined with belt drive), easy to clean, and impervious to dirt, mud, salt, and snow.
But one downside to the Rohloff hub has always been the necessary twist shifter, which can be slippery when wet and hard to twist if you have sweat, mud, or sun cream on your hand. The twist shifter is also less ideal for those with limited hand or wrist mobility, as it requires a lot of grip strength.
In addition, this shifter has always been awkward to fit to a drop bar bike.
The Rohloff twist shifter is difficult to mount on a drop bar bike. Image: Cycle Monkey USA
While many aftermarket solutions have become available over the years, everything comes with compromises to either the ergonomics of the shifter (awkward shifter location), shift performance (long lever throw) or reliability (added shifter complexity).
The neatest and most popular solution is the Gebla Rohbox, which allows you to use modified SRAM or Campagnolo shifters with your Rohloff hub. That said, some dislike the long lever throw and find it slow to change multiple gears in quick succession. Users have reported shifting glitches too.
Now we have a new aftermarket electronic shifting kit for Rohloff hubs that promises instant gear changes with very little effort, and neat integration with drop bar gravel bikes.
Let’s take a closer look at the SternShift system.
SternShift Electronic Shifting For Rohloff Hubs
A wiring diagram for the SternShift system. Note the dynamo hub that can trickle charge the battery!
This shifting kit comprises three main components: – An electronics box that contains the battery and the control board – A set of gear shifters at the handlebars – A rear gear mech that attaches directly to the Rohloff hub
This shifting kit is not wireless like you might expect. The system is instead fully wired from the shifters to the Rohloff hub. There is, however, a quick-release cable attachment at the rear wheel for quick and easy removal.
Mechanical engineer Hans-Hermann Herms spent three years developing the SternShift electronic shifting system. Approximately 50% of his time was focused on the hardware, and 50% on the software.
Flat or Drop Bar Electronic Shifting
The SternShift electronic shifters are available for both flat bars and drop bars.
The flat bar shifter clamps to the handlebar in the typical location and offers thumb shifting with dedicated up and down buttons.
The drop bar shifters are extremely compact and are designed to be mounted to the curved areas of drop bars. They are intentionally separated from the levers so that you are not tied to any specific brand of brake lever. To change gears, you use the sides of your thumbs to change gears (see video below).
Pressing the shifter buttons briefly changes one gear at a time. You also have the option of pressing and holding the shifter for a double-gear shift.
Hub Dynamo Powered or Battery Powered
The rear gear mech can be powered from a dynamo hub or battery. Image: Kinetics Online
You can choose whether you want a dynamo-powered or battery-powered SternShift system.
The dynamo-powered version is the neatest and most convenient, as the hub constantly supplies power to a small battery at the handlebars. The battery itself is capable of between 600 and 1800 gear shifts and can be optionally charged from a power bank while you’re cycling too. The charge level of the battery is displayed in green, yellow and red via an LED at the rear gear mech.
The system can also be used without a dynamo hub, although this is much less convenient, as it will require frequent charging from a battery bank.
Pressing the shift buttons for more than three seconds deactivates or activates charging. This could be useful if you have a separate USB charger wired into your dynamo setup, or if you want to send 100% of your dynamo power to some bright lights.
After 20 seconds of inactivity, the system switches to ‘sleep mode’ to save power. It will switch back on automatically when you move the bike or press a shift button.
If the gears are changed more than 20 times while stationary (presumedly by accident), the system can even switch to ‘protection mode’ until you start cycling again.
SternShift Stem or Electronics Box
The central element of SternShift is the electronics box, which contains the battery and the control board. It’s also the place where all of the cables come together.
You can hide these electronics inside a specially designed stem with ports for the three cables. The stem is currently only available in a 90mm length, and it has a ±6° angle.
Alternatively, there is an electronics box that’s mounted underneath your handlebars. This water-resistant tube houses a larger battery that can make three times more shifts between charges – if you aren’t powering the system from a dynamo hub, you’ll likely want this option.
Does SternShift Require A Special Frame?
The Rohloff OEM dropout is longer than usual to secure the internal gear components in place. Image: Tumbleweed.cc
Unfortunately, it does. The frame must have the long, non-drive side Rohloff OEM dropout to anchor the rear gear mech. That means you cannot use SternShift on a Rohloff frame that relies on the disc brake mount for its torque anchoring.
Is The SternShift System Waterproof?
SternShift is protected against water splashes, but not against full submersion. It also cannot be cleaned with a high-pressure washer.
Can The SternShift Change Gears Under Load?
SternShift will change your Rohloff gears quickly and precisely, but not with full pedal force.
It shifts the same as any Rohloff hub, which means that you must ease your pedal force for a fraction of a second to make gear changes.
How Much Does The SternShift System Cost?
The SternShift kit has just hit series production.
The retrofit kit is €799 and can be configured for dynamo or battery power, and drop or flat bars. If you want the electronic components hidden inside a specially designed stem, the kit price jumps to €949. You can also buy the SternShift stem by itself for €199.
And if you have particularly deep pockets, SternShift is available with all Rohloff gravel bikes from Falkenjagd and Rennstahl and can be ordered in the configurator.
For more information on this Rohloff hub electronic shifting kit, make sure to check out the SternShift website.
Internal gear bicycle hubs have been commercially available since 1898, and are typically found on bicycles used for transport, rather than high-performance sport.
They are a great alternative to derailleur gears, as they still offer multiple gear ratios, however, the critical drive components are all sealed away from the elements. This results in an incredibly low-maintenance drivetrain, that not only lasts longer but is less susceptible to damage.
Internal gear hubs normally use planetary gear sets to achieve different gear ratios, and you can get them with up to 14 different gears. These gears can be spread across a range even wider than a 1X MTB drivetrain.
You can also get continuously variable transmission hubs that have not just 14 gears, but an infinite number of gears between two set points.
In this article, we will examine the advantages and disadvantages of the Enviolo CVT hubs. We will later compare these hubs to the gold standard of planetary gear hubs (the Rohloff hub) as well as the closer-matched Shimano hubs. And lastly, I’ll explain exactly how this CVT hub works.
But first, what is a bicycle CVT?
What is a Bicycle CVT?
A bicycle CVT is a type of gearbox that eliminates the steps between each of your gears. Instead of shifting from your first gear to second, and second to third, the transition between gears is completely seamless, creating the smoothest shifting possible, and allowing you to ride at your perfect cadence – or crank rotation speed.
CVTs are common in industrial and automotive applications but are uncommon on bicycles. However, there are significant advantages to a bicycle CVT including a very user-friendly design, gear changes while stationary, no gear skipping, and an eerily silent operation.
And when paired with electronic shifting, you can even achieve fully automated shifting that keeps your legs spinning at your preferred cadence, no matter the speed, and without you even having to think about it.
So, where did this CVT technology come from?
NuVinci to Enviolo
A hub called the NuVinci 171 was released in 2006 by Fallbrook Technologies. At the time, it was about four kilograms (8.8lb), which was more than twice as heavy as any other gear hub.
Over time, the hubs were refined, the weight was brought down by 40%, the gear range was increased, and the hubs were engineered for a broader range of applications.
NuVinci was later rebranded to Enviolo as part of a bankruptcy restructuring.
These days the company is thriving. Over two million bicycles now use their CVT hubs, including many in bike share fleets around the world. You can find Enviolo-equipped bikes from over 150 different bike brands and a third of those use electronic shifting.
I’ve already touched on some of the advantages of internal gear hubs and CVTs, but it wouldn’t be a CyclingAbout article without a deep-dive analysis.
Advantages of Enviolo CVT Hubs
The User-Friendly Design
The big drawcard of a CVT hub is its user-friendly design. There is just one rotary shifter, and it’s highly intuitive to use. If you feel like your legs are spinning too fast, you wind the shifter one way, and if your legs are struggling up a hill, you wind it the other. It’s really as simple as that.
In addition, the Enviolo hubs can be shifted at any time (including while stationary) so it doesn’t ever matter if you’ve forgotten to shift.
The Instant and Stepless Gearing
As soon as you rotate the shifter, the CVT is instantly engaged. You never have to wait for any gear changes, and there is no chance of your chain skipping between gears.
The step-less gearing also ensures you’re never stuck in between gear ratios. This means your cadence can always be exactly as you desire.
The Electronic Shifting
If you use an eBike with a mid-motor, both electronic shifting, and automatic gear changes are possible.
First, you set your desired cadence in RPM on your smartphone (or eBike display). Then the motor and shifter will work together to automatically keep you at your perfect RPM – no matter the cycling speed.
And when you stop at traffic lights, the shifter will also put you in the perfect gear for take-off.
In addition, this system allows for ‘manual’ gear shifting in 5% increments simply by pressing up and down on the thumb buttons. This is particularly useful for riders who still want gear control, but have hand or wrist impairments. It’s also a great upgrade over the manual shifter too, for reasons we’ll discuss in the disadvantages section.
It’s worth noting that an electronic shifting retrofit is also possible on some eBike and hub combinations.
The Smooth and Silent Operation
Most internal gear hubs generate noise as the planetary gears are whirring away inside the hub body. Some hubs have more internal noise and vibrations than others, and there are even hubs out there that constantly tick while you pedal.
The Enviolo is the most silent gear hub of the lot – you almost never hear it working underneath you.
The Reduced Susceptibility to Damage
As there is no derailleur to knock or get things caught in, the Enviolo drivetrains are much less susceptible to damage. This is one reason why they’re so popular for bike fleets.
The Suitability For All Weather Conditions
Compared to derailleur gears, the Enviolo gear components are all hidden away and sealed from the elements. This reduces both component wear and drivetrain maintenance significantly.
The hubs can also be used down to -20° Celsius as well as in the planet’s hottest conditions.
The Low Maintenance Design
Incredibly, the Enviolo hubs are sealed for the life of the bike they are operating on. That means zero oil changes and zero bearing changes too.
The hub comes with a guarantee for 20,000km of use, but some users have reported exceeding 80,000km, which is similar to some Shimano Alfine or Nexus hubs.
The only maintenance required is cable replacements for the rotary shifter and possibly a service of the freewheel mechanism too.
The Relative Affordability
Compared to other gear hub options, the Enviolo products are considered affordable. And when you factor in the reduced need to replace worn components – these hubs become even more reasonably priced.
There are currently six different Enviolo hubs with prices starting at US $199 and maxing out at US $499. There is even a gearbox with a sprocket on both sides that’s intended for three-wheel cargo bikes.
When you spend more money, you essentially get a wider gear range, and more premium hub shell and internal components. You also get a higher input torque rating and hubs that can be fitted to heavier bikes.
The best way to compare Enviolo hubs is to look at the spec sheets on the website.
The Reduction in Chain Hassle
Provided you keep up your chain tension, you will also never experience dropped chains, skipping chains or chain slapping on your frame. It’s all the benefits of a single-speed bike but with infinite gear ratios.
The Belt Drive Compatibility
Better yet, you can pair Enviolo hubs with smooth and silent belt drivetrains. You’ve probably already noticed that most Enviolo-equipped bikes come with belts.
That’s because belt drive works out to be lower maintenance than chain drive, as it doesn’t require any grease or lubrication. As a result, belts stay very clean – you’ll never get black muck on your hands or pants ever again.
Belts also don’t rust, don’t stretch, and are very long-lasting too. Most cyclists go years without needing to replace a belt or sprocket. I’ve recently put 35,000km (22,000mi) into a belt drivetrain, which is more than three times further than I’d expect from a well cared for chain.
But if you prefer a lower-cost chain drivetrain, remember that you can fit a chain case with an Enviolo hub. This keeps water and grit away from your chain, and will likely double its wear life.
The Stronger Rear Wheels
Enviolo hub flanges are both the same height and are spaced equally from the frame on both sides. Unlike a typical cassette hub, this results in even spoke tension, building the strongest wheel possible.
The High Input Torque Rating
High-torque eBike motors are a great way to damage internal gear hubs. The good news is that the Enviolo hubs are rated up to 100Nm input torque, which is higher than the Shimano Nexus 5-speed hub (85Nm).
Some manufacturers such as EVELO have found the Enviolo Trekking hub will comfortably handle a 600-watt, 120Nm motor. According to the company, Enviolo hubs are their most reliable gear system with less than a 1% warranty replacement rate. They have so much confidence in the hubs they even extend the warranty duration.
Right, after all that I probably sound like a spokesperson for Enviolo, so we need to look at the disadvantages too.
Disadvantages of Enviolo CVT Hubs
The Drive Efficiency
Image: FahrradZukunft.de
When you put pedal power into the Enviolo hub, some of that power is lost through the transmission.
Most internal gear hubs are somewhere between 3% and 7% less efficient than a perfectly clean and lubricated derailleur drivetrain (on average). In comparison, the Enviolo CVT hub is around 14% less efficient (on average).
Now, I know 14% sounds like a lot, but this is really not a big deal for many users, notably those who use their bikes for transport. And the benefit of always using the perfect cadence might even outweigh the drive efficiency loss.
When using a regular bike on a 5km flat trip along a bike path, I’ve calculated you might lose 20 seconds over 11 minutes compared to a Shimano internal gear hub (200W @ 100kg weight, gear 6). And if you were to use an eBike, you could expect slightly less range from your battery. But we’re talking a handful of kilometres here compared to other gearboxes – it’s nothing drastic.
This is obviously no big deal for short urban trips, but the battery range or time penalty might of course add up for long-distance use.
The Weight
These hubs are around 800 grams (1.8lbs) heavier than a Shimano Alfine internal gear hub with a similar gear range. And they are around 700 grams heavier than a Rohloff hub that offers a much wider gear range.
Now, I’ve said this before and I’ll say it again: bike weight affects cycling speed much less than you think. This is because 800 extra grams is likely just 1 or 2% extra weight to your overall system weight (body+bike+gear).
When we run the calculations, this weight difference will barely slow you down on the flat, and in the hills, it’s likely just a one or two-minute penalty per 100km of cycling.
Where weight becomes more important is if you frequently carry your bike up and down stairs.
The Heavy Shift Actuation
Some people find the Enviolo manual shifter to be quite stiff to rotate. And it’s even harder to change gears when the shifter gets wet.
If you have hand or wrist issues, the Shimano Alfine hubs with a trigger or Di2 shifter might be the better option. Or if you’re planning on using an eBike anyway, simply choose the Enviolo electronic shifter.
The Fast-Wearing Shift Cables
Image: Auren Bikes
The Enviolo hub when coupled with the manual shifter is notoriously tough on cables. However, the duration the cables stay in good working condition is usually based on how smoothly and carefully you shift.
Here are a couple of things to keep in mind when shifting.
Firstly, make sure to back off on your pedal power for a split second to make your shifts. This takes a bit of time to master but becomes second nature in no time. Doing this allows the internal hub components to move with ease, putting less strain on your cables.
Secondly, you don’t want to force the shifting. You often cannot rotate the shifter across the full gear range when your bike is stationary, so only rotate it as much as the hub will allow. It’s also quite easy to strain the cables by rotating the shifter past the highest and lowest shift points, so try to be aware of these limits.
And lastly, maintain your cables! This involves keeping them clean and lubricated, making sure the cables have the appropriate tension, and checking for any sharp bends in the external housing.
If you keep these things in mind, your cables can last for years.
The Wheel Removal
Rear wheel removal is not quite as easy on an Enviolo bike.
With the electronic shifting, you just pull the connector cable and can remove your wheel with a spanner or Allen keys (depending on the hub model).
It’s a bit trickier with the manual shifter because two cables must be unhooked from the hub interface before dropping your wheel. Also, make sure to avoid bumping the hub interface as you can accidentally reduce the gear range of your hub.
If the hub interface is moved, the Enviolo channel has a video showing you how to reset it.
The Low Gear That’s Not That Low
The Enviolo hubs require a minimum front-to-rear sprocket ratio of 2:1. This results in a climbing speed of 8kph when you’re pedalling at 60RPM or a low gear of approximately 28 gear inches.
To put this into context, the climbing speed on many mountain bikes is often 30 to 40% lower. And even lightweight gravel bikes have a 10% lower climbing gear.
While this climbing gear is perfectly adequate for most urban uses, if you’re planning on cycling in hilly terrain without electric assistance (think 10% or steeper), the Enviolo climbing gear is likely not low enough.
The Gear Range
The gear range of the Enviolo hubs is between 256% and 380%. This simply means the top gear is 2.56 times (or 3.8x) bigger than the smallest gear.
To put these numbers into context, modern derailleur drivetrains exceed 500% gear range, and there are gearbox drivetrains that even exceed 600%.
Again, a smaller gear range works for most urban environments. That’s especially the case if you have electric assistance. Where it becomes a bit limited is if you want to climb both steep hills and have the gears for high-speed cruising too.
The Need To Send Away Enviolo Hubs For Repair
The Enviolo hubs are not a typical product found in bicycle stores outside of Europe, so you might need to send your hub to a service centre for repair. And yes, there is a big service centre in the United States.
In other regions, the bike companies that sell Enviolo-equipped bikes are usually able to help.
But it’s worth noting that problems with the hubs are quite uncommon, and most issues can usually be solved by changing the shifter or replacing the cables and/or freewheel mechanism.
Right, let’s find out what the extra US $1000 gets you if you were to upgrade to a Rohloff hub.
Enviolo Hub vs. Rohloff Hub
In short, buying a Rohloff ensures a longer-lasting hub, that’s lighter, much more efficient, and with both lower and higher gear ratios. It will also handle more torque from a mid-mount eBike motor.
Rohloff hubs are known for their long-term durability – there is even a Rohloff out there that has travelled 500,000km, which is five to ten times further than you can expect from an Enviolo.
When it comes to drive efficiency, the Rohloff has been tested to be over 94% efficient across its entire gear range compared to Enviolo’s 83% (average). With all things being equal, this results in around a 1.5kph difference in speed on the flat (200w, 100kg total weight) making the Rohloff undoubtedly the best option for long-distance use. It’s also the best way to get the maximum range from a battery.
The Rohloff also offers a 526% gear range compared to Enviolo’s 380%. This allows you to ride at both much lower and higher speeds.
The lowest permissible gear ratio can be set considerably lower on a Rohloff, making steeper hills much easier to conquer. In fact, the lowest permissible gear on the Enviolo is the equivalent of the sixth gear on a Rohloff!
The Rohloff is not only 700 grams lighter but it will handle up to 130Nm from a mid-drive eBike motor. In comparison, it’s 100Nm with some Enviolos.
There are more shifter options with the Rohloff too. If you want to use drop bars, you have the option between Cinq integrated shifters or even SRAM shifting using the Gebla Rohbox. And if you use an eBike, the Rohloff has electronic shifting too.
I hope you can now see where the value lies in a Rohloff hub. But the advantages of the Enviolo should not be taken lightly. The hub is quieter, more user-friendly, has automatic shifting, requires zero oil changes, and is offered at a fantastic price.
A fairer comparison might be to the Shimano hubs…
Enviolo Hub vs. Shimano Hubs
When we compare the Enviolo to the Shimano hubs, we get a much closer match-up in terms of price (US $200-500), gear range (409% vs 380%), lowest permissible gear ratio, and long-term durability (both around 80,000km).
It could be said that the Shimano feels snappier and sportier with its distinct gear changes, and the 800-gram weight saving helps in this regard too.
The drive efficiency difference is around 7%, which results in a 1kph faster cycling speed on the flat for the Alfine hub (200w, 100kg total weight, flat road).
The Alfine also uses a trigger shifter, which is often preferred over the Enviolo’s rotary shifter. And you don’t need an eBike to use the electronic shifting options for Shimano hubs too.
That said, the Shimano hubs are a bit noisier, the gears can skip if you don’t maintain the cables well, the auto shifting is not as seamless, the input torque rating is lower (85Nm), and the hubs require regular grease or oil changes.
And finally, let’s go inside the Enviolo hubs to see how they work.
We are looking at the hub from the back of the bike, so the sprocket is on the right side, and the disc rotor is on the left.
Here you can see the main shift components: there are two rings and a set of large metal spheres that sit on an idler. The input ring on the right side is connected to the rear sprocket, which is driven by your legs. And the output ring on the left side is what propels your bike forward.
Power from your pedals moves from your rear sprocket to the first ring, then into the spheres, and then from the spheres to the second ring, and finally to the wheel.
One reason why Enviolo hubs are somewhat inefficient is due to the metal spheres that are moving in a slightly different direction (and at slightly different speeds) to the two rings. This is known as “contact spin”.
Interestingly, these components are not directly touching. Instead, a specially-designed oil passes through microscopic spaces between the components, solidifying momentarily under pressure, and transferring the pedal power. This is why there is such little wear inside Enviolo hubs, and why you don’t need to service them.
To understand how this hub achieves its infinite gear ratios, we need to take a closer look at the spheres.
When you twist the shifter at the handlebar, the idler on the axle tilts the spheres. This changes the contact patch size on the spheres that the rings interact with.
When the contact patch is large on the right side and small on the left side, the wheel will spin slower than the rear sprocket (underdrive). When the contact patch is small on the right side and large on the left side, the wheel will spin faster than the rear sprocket (overdrive). And when the contact patches are identical on both sides, the wheel and sprocket will move at the same speed (1:1).
Summary
Congratulations, you now know virtually everything about Enviolo hubs, including how they work!
I think these hubs are super cool. They are intuitive to use, require little maintenance, are super silent, and the fact that they’re priced well only makes them more appealing. Even as a very experienced cyclist, the Automatiq gear shifting was an absolute delight to use.
Yes, the hubs are a bit heavy and inefficient. But for many user groups, I’m not really sure that matters.
If you’re after the best-performing and longest-lasting hub, you will still be best served with a Rohloff. And for a sportier ride experience, as well as more shifter options, I think the Shimano hubs are the way to go.
The Kinetics MTBrompton is a new off-road version of the Brompton folding bike.
Normal Bromptons use tiny 16″ wheels with 35mm (1.35″) wide tyres. This wheel size is key for providing the famous small fold, but it also compromises the performance of the bike in some situations – namely on rougher surfaces such as cobblestones, gravel roads and forest trails.
But you no longer need to compromise – you can now trade some of your Brompton’s folded size for a much more capable bike.
This is thanks to the Scottish bike shop and custom bicycle fabricator, Kinetics, who have created the MTBrompton upgrade kit. I covered this shop’s custom Brompton work in the video above (written version here).
The Kinetics MTBrompton upgrade kit is essentially two things: a taller and wider fork, and a longer and wider rear frame triangle. These pieces will bolt directly to any Brompton frame.
With this upgrade kit, your Brompton will also be compatible with disc brakes, various high-end internal gear hubs and even Gates Carbon belt drive.
And if you don’t currently have a Brompton, you can purchase one through Kinetics and they can customise it to your every need.
Why Off-Road Bromptons Are More Capable
The MTBrompton fitted up with Schwalbe Smart Sam off-road tyres. Image: Kinetics-Online.co.uk
While Brompton folding bikes typically use 16″ wheels with 35mm wide slick tyres, the MTBrompton offers 20″ wheels and 60mm wide off-road tyres.
Don’t worry, the MTBrompton still folds up just like a normal Brompton. However, with the new big wheels, it can handle much rougher off-road tracks.
This is partly due to the larger diameter wheels having a smaller ‘angle of attack’ over obstacles. Larger wheels allow you to maintain higher speeds when the surface is rough, and the extra voluminous tyres will deform more over bumps and depressions in the road, providing a much smoother ride – and more traction to boot.
The larger wheel format also gives you access to off-road tyre treads. You can pick from fast-rolling touring and gravel tyres with minimal tread, right through to sticky mountain bike tyres that have the maximum grip and traction possible.
If you want to achieve the highest average speeds on the road, the 20″ option is about as fast as it gets for a small folding bike. You can even get Schwalbe’s top-of-the-line Pro One road bike tyres in the 20″ size, which literally halve the rolling resistance of a typical Brompton tyre.
The MTBrompton Drivetrain Options
This MTBrompton has been decked out with a Rohloff 14-speed hub. Image: Kinetics-Online.co.uk
The MTBrompton is incompatible with typical Brompton gears, but that’s ok because you now have the opportunity to upgrade to a higher-performing internal gear hub, and belt drive too!
I’ve written extensively about Shimano Alfine 8 and 11-speed hubs, which are amazing value for money and are definitely recommended on an MTBrompton build.
However, if you want the most efficient and the most durable hub available, you will want to invest in the infamous Rohloff 14-speed hub. This has been my hub of choice for over 150,000km of bicycle touring now.
The MTBrompton Bottom Bracket Height
The bottom bracket is much higher on an MTBrompton. Image: Reddit.com/user/platmack
One compromise that you need to make with an MTBrompton is the height of the bottom bracket shell (BB).
As the Brompton mainframe is unchanged through the upgrade kit, the BB sits around 350mm off the ground, which is 30-40mm higher than a hardtail mountain bike (and 80mm higher than a regular Brompton).
This isn’t a huge deal, in fact, it will help prevent both pedal strikes with the ground, and front chainring strikes on obstacles. But the additional ride height will feel a bit like you’re riding on top of the bike, rather than in it. And your saddle will now be 80mm higher off the ground, making it a bit harder to get on.
This will certainly be noticeable if you’re coming from a 16″ Brommy, but you probably won’t realise it if you spend time on mountain bikes.
You can expect the folded size to be around 140mm longer, 45mm taller and 80mm wider than a regular Brompton, which is still a very manageable size for an apartment or public transport use.
Kinetics include some “ears” for the bike to stand on when folded. The folded bike is said to roll nicely on the back wheel, so it doesn’t need the typical Brompton rollers.
The MTBrompton Weight
The Rohloff hub version pictured above with Schwalbe Big Ben tyres comes in at 14.6kg (32.2lb).
This is not particularly light for a folding bike, but the Brompton steel frames are known for their durability, and the Rohloff 14-speed internal gear hubs are as tough as they come.
The MTBrompton Price
Kinetics finish the modified Brompton frames up nicely. Image: Reddit.com/user/rafikiphoto
The MTBrompton upgrade kit is a niche, handmade product that’s made in very small quantities in the UK. The result is an expectedly expensive price tag.
A disc brake upgrade is a necessity on the MTBrompton, as the regular rim brake calipers don’t offer enough tyre clearance for 2.4″ tyres. And the original Brompton hubs are incompatible with disc brakes, so you will need to shell out for a new internal gear hub too.
Here’s the minimum price for the full Kinetics upgrade: 1x MTBrompton rear triangle with a Shimano Alfine 8-speed internal gear rear wheel (£795) 1x MTBrompton fork + 2x TRP Spyre disc brakes + 1x front wheel (£565) 2x Schwalbe tyres (£100) Total: £1460 (~US $1840)
If you do not currently have a Brompton bike to upgrade, the bike itself adds £1200 to the purchase price. The total for a complete MTBrompton starts at £2660 (~US $3350).
A size comparison between the MTBrompton and the regular Brompton. Image: Reddit.com/user/rafikiphoto
It’s worth noting that Kinetics also offer Kindernay 14-speed, and Enviolo CVT gear hubs for an extra cost. In addition, you can upgrade the Shimano Alfine hubs to electronic shifting (Di2).
If you’re shipping a MTBrompton internationally, you can remove 17% from the purchase price. You don’t have to pay UK VAT, but you will have to pay shipping plus some tax or import duty when the package reaches your country.
Similar Off-Road Folding Bikes
The Eerder Xplorer paved the way for the MTBrompton. Image: EerderMetaal.nl
The MTBrompton isn’t the only folding bike with 20″ wheels and wide off-road tyres.
Eerder Metaal over in the Netherlands is making some beautiful custom off-road Bromptons. These bikes have a touch more tyre clearance (2.6″), and the option for derailleur gears, fenders, luggage adapters, travel bags and more.
Eerder Metaal even shaves down the head tube of the main frame. This allows the fitment of a long fork that clears a wide tyre and fender, but all while keeping the bottom bracket at a reasonable height. As a result, the Xplorer has a 30mm+ lower BB compared to the MTBrompton (315mm with 2.25″ tyres), and a slacker head tube angle for better off-road bike handling too.
Additionally, there are no “ears” for the Xplorer to stand on when folded. It instead sits on four rollers that are neatly integrated into the rear triangle and fender. This allows you to easily roll the Xplorer about with a front bag attached (see video).
The waitlist is significantly longer from Eerder Metaal, and they are priced a bit higher due to the extra custom work (€5500 as pictured above).
The Bike Friday All-Packa folding bikepacking bike. Image: BikeFriday.com
Bike Friday offers a model called the All-Packa folding bike, and it has the same wheel and tyre specification as the off-road Bromptons.
The All-Packa is a fair bit cheaper (US $2495) and lighter (12.5kg/27.6lb). As the frame has been designed from the ground up, the bottom bracket height is 75mm lower than the MTBrompton. This height is ideal for gravel riding (the bike’s intended use) but could be a bit low for riding over obstacles.
The Bike Friday All-Packa has a slower and larger folded size (if that matters to you) and uses a typical derailleur drivetrain. The bike is made in the USA and gets a lot of praise in online reviews.
The Birdy GT is a capable off-road folding bike. Image: MightyVelo.com
Birdy is the original off-road folding bike company.
While the wheel diameter is a bit smaller (18″ rather than 20″), Birdy uses front and rear suspension to provide a smooth and fast ride over rough terrain. You can expect the Birdy GT to ride just as well off-road (if not better) than the Bromptons with wider tyres.
In comparison to other folding bikes I’ve mentioned, the bottom bracket height is 60mm lower than the MTBrompton and a touch higher than the All-Packa.
Thanks to the monocoque aluminium frame, the Birdy GT is the lightest folding bike of the lot (11.4kg/25.1lb). It’s available in a bunch of colours at prices starting at US $2600 and jumping up to US $4900 if you’d like a Rohloff 14-speed gear hub.
Summary
The MTBrompton still has the signature neat fold. Image: Kinetics-Online.co.uk
Bromptons are some of the smallest folding bikes available, and their ingenious design allows them to fold down in just a handful of seconds (the world record is five seconds).
However, the 16″ wheel size with narrow slick tyres is limiting for mixed-terrain riding. And the available gear systems are frankly quite clunky compared to other gear systems available.
The Kinetics MTBrompton upgrade kit allows you to have it all. You can ride comfortably on the dirt and cobblestones without losing the great Brompton fold. And you get a much more refined internal gear hub and brakes too.
Honda is the largest motorcycle manufacturer by a huge margin, and they’re one of the largest car manufacturers too. They have built Formula 1 cars, jet aircraft, robots, boat engines, and lots of power equipment.
The company channels around 6% of their annual revenue into research and development, making them particularly well-known for its innovation.
But Honda’s innovation isn’t just limited to products with motors. Two decades ago, they were experimenting with some top-secret bicycle gearbox drivetrains. And after a handful of seasons on the downhill World Cup MTB circuit, the Honda gearbox bikes had won the world championships and five World Cup rounds.
Unfortunately for us, the gearboxes that Honda developed were never meant to be commercial products. It turned out that Honda poured money into this program purely to challenge the minds of their engineers.
As the patents on these gearboxes are expiring soon, I thought this would be a great time for us to analyse all three generations of the Honda bicycle gearboxes. You’ll learn about the designs and how they all work, we’ll examine why there aren’t more gearboxes following similar designs, and we’ll look into the next generation of gearboxes in this space.
But first, let’s find out the advantages and disadvantages of using a gearbox over a derailleur drivetrain for mountain bike racing.
The Advantages of a Gearbox Drivetrain for Racing
One big advantage on a downhill race bike is the reliability boost via additional ground clearance. Derailleurs hang low on a bike and are susceptible to damage from rocks, sticks and crashes. On a short-timed run, a broken derailleur, or a missed shift, can be the difference between winning and losing.
Additionally, a gearbox has the ability to instantly shift gears without the need to pedal. This allows riders to pre-load the perfect gear before a corner, in the air, or while riding through a rock garden.
Speaking of rough terrain, by moving the shift components to the centre of the bike, the rear suspension performance can be improved due to a reduction in unsprung mass at the rear wheel. This allows the rear suspension to react faster, increasing traction, and the bike can also handle better with the weight central and low.
A modest boost in performance could also be found in adverse riding conditions. Derailleurs and jockey wheels can get jammed with mud and grit, affecting their ability to shift or operate efficiently. A gearbox seals away many of these critical drive components.
But really, the biggest advantages of bicycle gearboxes are realised at the consumer level, as you get an incredibly low-maintenance drivetrain, that’s weather resistant, crash resistant, and with fewer components that will wear.
Why Are Derailleurs Still Common in Racing?
Simply put, derailleur drivetrains are the lightest gear system with the highest drive efficiency, which in bike racing, is the perfect recipe for winning. This is why almost all bicycles raced at the top level use derailleurs.
Mountain bikes with derailleur drivetrains are, at minimum, one to two kilograms lighter than gearbox bikes (2.2-4.4lb). Derailleurs can also transfer more of your pedal power to the rear wheel – it works out at around 5% more power than if you were using a Pinion gearbox (in ideal riding conditions) but this number can narrow depending on the power output and cadence of the rider, along with the riding conditions, lubricants used, chain contaminants, drivetrain wear, and much more.
This is a prototype of the third-generation Honda bicycle gearbox.
In addition, derailleurs allow for a very broad variation in bicycle frame design, as a rear hanger is the only necessary infrastructure for installing gears on a bike. In comparison, the packaging requirements of a gearbox significantly limit the ability of a frame designer to optimise the suspension layout.
And lastly, derailleur drive components can be quickly and easily replaced, which is ideal for mechanics who have limited time for race repairs. And it’s even more ideal for derailleur manufacturers who really like selling derailleurs.
Right, let’s get into what you’re really here for – the Honda gearbox tech!
The Honda CVT Gearboxes
This Honda RN01 features the second-generation CVT gearbox.
The first two Honda gearbox generations are, by far, the most fascinating – but unfortunately, there are very few photos and limited information about them outside of their patent.
The first two generations of Honda gearboxes were neither. And they didn’t even have set gear ratios! They instead used a camshaft and a series of levers to change the drive ratio.
These photos show Honda’s first-generation CVT gearbox in a very early prototype.
Very few people knew of these gearboxes, and even fewer understood how they worked. Stick around until the end and I guarantee a cam and lever bicycle gearbox will make sense to you.
Why did Honda design their earlier gearboxes this way?
Firstly, you got to choose from an infinite number of gears between two set points – this is known as a continuously variable transmission, or CVT. Shifting was instantaneous, and the gearbox would never ‘skip’ like a poorly-tuned derailleur.
The second-generation CVT gearbox was shown at a motorcycle trade show in 2002.
The CVT gearbox was also particularly compact by the second generation – almost half the volume – and in theory, could be quite efficient too.
Unfortunately, the Honda CVT boxes were seen just a handful of times at bike races and trade shows, and were never raced on the World Cup circuit. We will never know why Honda shelved these earlier gearboxes, but that’s ok because they had another gearbox ready to go.
The Honda Derailleur in a Box
The G Cross Honda team burst onto the downhill World Cup circuit in 2004 with a bunch of talented riders. The Honda bike ended up winning the first World Cup race it was entered in, instantly proving the carbon-shelled gearbox was the real deal.
For more than a year, we could only guess what was inside the third-generation gearboxes, as they were racing with them long before anyone was allowed to look inside. In fact, Honda mechanics performed all gearbox maintenance hidden from view, and the gearboxes were never stored with the bikes. Instead, the gearboxes stayed inside hotel rooms with the mechanics to not only prevent theft but to keep the design a secret.
The Honda derailleur in a box was simple and effective.
After the patents were eventually made public, we found out that the latest gearboxes were nothing particularly genius. The solution was a derailleur-in-a-box: a 7-speed gear system that used the same components as a regular drivetrain, but was all sealed away from the elements.
While not as innovative as the CVT boxes, the internal derailleur drivetrain still achieved Honda’s goals of shifting without pedalling, reducing the unsprung mass at the rear wheel, and creating a gear system that was less susceptible to damage.
The gearbox worked by transferring pedal power into a sprocket located on the crank spindle. When this sprocket turned, it would drive the internal chain onto a small cassette where the gear ratio was selected. The cassette then directly drove the external sprocket, which went on to drive the rear wheel.
The freewheel for this drivetrain was located at the crank spindle, which meant that whenever the rear wheel was moving, the internal chain was running, and the gears could be changed without pedalling.
A really cool thing about this miniaturised derailleur drivetrain was that the chain line was always straight because both the sprocket on the crank spindle and the derailleur moved in unison when you shifted.
A straight chain line is key for ensuring a high drive efficiency – some quick maths suggests this drivetrain would likely operate within 2% of a regular derailleur setup, but it could be more efficient in adverse conditions.
While the Honda gearbox was refined and race-proven almost 20 years ago, it’s worth noting that PeteSpeed had a very similar patented gearbox on bikes at around the same time. This design was later licensed by Hayes, but I don’t think it ever made it onto any production bikes.
The Downsides of a Derailleur in a Box
As a derailleur-in-a-box uses existing bike components and offers a high drive efficiency, it seems like an ideal solution for a gearbox bike. So, why aren’t bike manufacturers working on this tech for consumers?
One issue is the physical size of the gearbox – when the box becomes too large, it considerably limits frame design. Just look how big the Honda box was when it was using a tiny road bike cassette with just over 200% gear range. If we were to squeeze in a modern cassette from a 1X drivetrain (eg. 10-52t), it would be monstrous!
To maximise bike compatibility, gearboxes are currently being designed around eBikes as well as regular bikes. With the extra packaging constraints of a motor and battery, this makes a derailleur-in-a-box even less commercially viable.
But despite these downsides, people are still forging on with this concept.
The Next Generation
Williams Racing Products have an interesting new gearbox in the works.
Williams Racing Products has recently been teasing a working prototype of a derailleur in a box. This design is impressively compact, and might even fit a standardised frame design in the future. But again, the gear range is limited to the cassette size that will fit inside their box.
Cesar from UNNO bikes holds a recent patent for a similar gearbox, so there are likely working prototypes in existence. The interesting thing is that there is no derailleur inside this gearbox, instead, it’s the cassette that slides back and forth. This is cool, but it creates further packaging issues due to the extra gearbox width.
Cesar Rojo from UNNO bikes holds a patent from 2017 for a derailleur in a box.
Three years ago, I made an in-depth video about Shimano’s 13-speed gearbox patent that uses a form of derailleur. Again, a very cool design, but right now in 2023, there are no updates on its development.
And Nicolai bikes have always been tinkering with gearboxes, however, the most recent derailleur-in-a-box prototypes are now a decade old.
Ok, let’s switch gears for a bit, and find out how Honda’s first and second gen CVT gearboxes worked. I think you’ll find this bit particularly fascinating!
How Does the Honda CVT Gearbox Work?
Here’s a cross-section of the CVT gearbox to help us understand it. The crankset is located down the bottom and the output sprocket is located up the top.
We can break the gearbox into three key sections:
The first section increases the rotation speed of the sprockets inside the gearbox. This allows the final sprocket to spin about 11x faster than the crankset – meaning this gearbox moves at around 1,000RPM under a typical rider cadence (90RPM).
The speed of the sprockets is increased using three gear sets: one from the crank spindle to a separate assembly, another gear set back the crank spindle, and another to a special sprocket housed on a camshaft.
The second section is all about turning rotation into a repetitive linear movement using a camshaft. The last sprocket from the first section of the gearbox is connected to an eccentric cam, so every time it spins, a series of four connecting links can move up and down. The best way to understand what’s going on here is to imagine a piston going up and down.
We now need to look at a line drawing to understand what happens next, and this is where it gets a bit tricky to follow. The lower link is the camshaft, and the upper link is connected to the final section of the gearbox, the one-way clutch. Every time the camshaft moves up and down, it moves the upper link up and across, along a circular path.
The final section is all about turning our reciprocal movement back to rotary movement. As the upper links move on a circular path, Honda employed a one-way clutch so that only the rearward movement would drive the external sprocket, while the forward movement would simply “freewheel” – to put it into bike terms. This clutch would operate similarly to an Onyx rear hub, offering instant engagement.
But here’s where things get crazy. Our external sprocket would not move in a totally smooth motion if the clutch is constantly engaging and disengaging, so the geniuses at Honda designed a wavy gear set that can offset these oscillations.
And what about the infinite gears?
Well, a twist shifter at the handlebar adjusted the geometry of the drive links. When the shift actuator arm was high – as shown in this upper gearbox line drawing – the camshaft pushed the clutch a shorter distance per rotation than when the shift actuator arm was down. The distance the clutch moved in the highest gear was about 3x further than the lowest gear – resulting in a ~300% gear range.
The geometry of the links could be manipulated anywhere between these two points when shifting, and this is what gives us an infinite number of gear options.
Summary
Two decades ago, Honda did something very impressive. To create a gearbox bike that could keep up with derailleur bikes at the top level was unheard of back then, and hasn’t been done since.
Their derailleur-in-a-box design was so simple and effective in execution, I’m surprised we haven’t seen it replicated in downhill mountain bike racing, where the design clearly works.
That said, the Honda and PeteSpeed patents expire soon, and we’re seeing new prototypes coming through – so perhaps the next derailleurs-in-boxes are closer than not.
The first and second-generation CVT gearboxes were truly innovative, with their camshafts, links and one-way clutches. I’d love to know why the idea wasn’t pursued further, but I suspect that’ll stay as Honda’s little secret.
Brompton is a folding bike company that builds around 80,000 bikes per year out of its factory in London.
These are some of the smallest folding bikes available, and their ingenious design allows them to fold down in just a handful of seconds. The bikes are somewhat light, very durable and quite comfortable to ride – plus, you can push them around very easily in their folded state. They are a great bike to combine with public transport, store in an apartment, hide under your desk, or take with you overseas.
But these folding bikes are far from perfect, and there is a large aftermarket industry that aims to make your Brompton better.
For example, you’ve been able to find the components required to build ludicrously lightweight custom Bromptons for many years. I’m talking folding bikes absolutely dripping with carbon and titanium and weighing under 5kg/11lb.
Just this year, Brompton released their own lightweight titanium model – a 7.45kg/16.4lb bike that might not have come about if the aftermarket industry hadn’t paved the way first.
In this article, I’ll be explaining some of the aftermarket features available for Bromptons – including bigger wheels, wider tyres, gearboxes, belt drivetrains and disc brakes. These popular upgrades might just give us a glimpse into the future of Brompton bikes.
Aftermarket Brompton Wheel Diameters
The Eerder Metaal Xplorer has the biggest wheels you’ll ever see on a Brompton! Image: Eerder Metaal
Let’s start with the wheel diameter.
Brompton Bikes use 16″ wheels with 35mm (1.35″) wide tyres. This wheel size is key for providing the famous small fold, but it also compromises the performance of the bike in some situations.
Studies conducted by Schwalbe tyres have shown that rolling resistance losses are inversely proportional to the tyre radius (approximately). This means that larger diameter wheels have a lower rolling resistance than smaller diameter wheels (using the same tyres).
Some quick maths suggests that switching from 16″ wheels to 20″ wheels could increase a rider’s speed by one kilometre per hour, lopping about three minutes off an hour-long ride.
In addition, larger diameter wheels have a smaller ‘angle of attack’ over bumps and depressions in the road surface, allowing a rider to maintain higher speeds if the surface is less than ideal.
Brompton tyres are often just 35mm/1.35″ wide, which is a touch wider than you’ll find on modern road bikes. These tyres are great on smooth surfaces, but on less than ideal surfaces, higher volume tyres can float over bumps much better, with only a minor increase in rolling resistance.
Ultimately, folding bikes trade off between folded size and performance. Based on the aftermarket options available, it seems lots of people are seeking a more versatile Brompton.
Let’s take a look at the aftermarket wheel options.
Birdy offers 18″ and 20″ wheels for their folding bikes, two wheel diameters used by the Brompton aftermarket. Image: Mighty Velo
There are two common wheel diameter upgrades for Bromptons – 18″ (355) and 20″ (406).
To complete a wheel and tyre upgrade, you’ll also need a new fork and rear triangle to match. Kinetics in Scotland manufactures steel forks and stainless steel rear triangles that will suit 18″ x 2.0″ tyres or 20″ x 1.3″ tyres.
The number one reason to use 18″ wheels is to fit tyres with significantly more air volume. 2.0″ wide tyres deform more over cobblestones and dirt paths, which improves both your comfort and speed on these surfaces. This wheel upgrade is likely the perfect balance between folded size and mixed surface bike capability. There are some great 18″ tyre options too, as Birdy folding bikes are built around this spec.
If you want to achieve the highest average speeds on the road, the 20″ option is about as fast as it gets for a small folding bike. You can even get Schwalbe’s top-of-the-line road bike tyres in the 20″ size, which literally halve the rolling resistance of a typical Brompton tyre.
Even with big wheels, the Eerder Metaal Xplorer still folds up quite small. Image: Eerder Metaal
On the opposite end of the spectrum, Vincent at Eerder Metaal in the Netherlands goes a step further and offers custom Brompton builds with 20″ wheels in a 2.6″ width. To make these large wheels work, Vincent uses a custom fork and rear triangle, and he even shaves down the headtube of the frame.
The Xplorer is the ultimate dirt road Brompton – Vincent has tested his bike on lots of mountain bike trails and has found that it’s surprisingly capable. He has built up Xplorers with both derailleur gears and internal gear hubs.
The folded size is 14cm longer, 4.5cm taller and 8cm wider than a regular Brompton, which is still a very manageable size for an apartment or public transport use.
This Brompton by Kinetics (Scotland) is custom-built around 3.0″ wide tyres. Image: Kinetics
Another interesting aftermarket wheel dimension is 16″ x 3.0″.
This is actually a smaller rim diameter than what is found on stock Bromptons, but it allows for the super-wide tyres to fold into a very small package. The advantage of this width is that you can run especially low tyre pressures to float over sand, mud or cobblestones.
Brompton Gearbox Drivetrains
This Brompton by Kinetics (Scotland) is built to fit a 14-speed Rohloff hub. Image: Kinetics
Brompton Bikes has a few different drivetrain options. You can opt for no gears (singlespeed), two or four-speed derailleur gears, a three-speed internal gear hub, or a combination of a derailleur and the three-speed hub providing six gears.
The gear range that Brompton offers on these drivetrains is between 133% and 302%. This simply means that the biggest gear ratio is 1.33x times bigger than the smallest ratio on the two-speed bike, and it’s 3.02x bigger on the six-speed bike.
With bigger gear ranges, we can pedal our bikes across a broader range of speeds, which is especially handy for hill climbing or pedalling downhill.
Thomas Inderka at Faltradritter built a Brompton with an 18-speed Pinion gearbox with the help of Vincent (Eerder Metaal). Image: Faltradritter
In comparison to other bikes, the Brompton gear ranges are quite small. Road bikes typically have more than 400% range, and mountain bikes more than 500%.
To increase the capability of a Brompton, the aftermarket is producing custom rear triangles that fit all of the best internal gear hubs. Rohloff and Kindernay are considered top of the crop and offer 14 gears that are spread across a 500%+ range. Alfine 8 and 11-speed hubs are popular too, thanks to their lower cost, and I’ve seen a few bikes with Enviolo CVT hubs too.
Faltradritter in Germany even customised a Brompton frame to house a Pinion gearbox! This gearbox has an incredible gear range of 636% and 18 individual gears, which gives this Brompton owner the ability to ride up the steepest hills and still have gears for the strongest tailwinds.
Belt Drive Bromptons
Vincent at Eerder Metaal built one of his Xplorers with belt drive and a Rohloff 14-speed hub. Image: Eerder Metaal
When you add a gearbox drivetrain to a bike, you can also switch to a belt drivetrain.
Belts are a particularly good fit for Bromptons because they’re ultra-long-lasting, aren’t greasy and require almost zero maintenance. For these reasons, I would not be surprised if we saw a belt drive Brompton rolling out of the factory soon.
Disc Brake Brompton Bikes
With the aftermarket providing new forks and rear ends to house bigger wheels, gearboxes and belt drive, this gives them the opportunity to add disc brakes too.
Disc brakes aren’t an essential component by any means, although they are nice in wet conditions and are generally very reliable, given that grit cannot work its way into the hydraulic lines. But with fatter tyre bikes, the regular Brompton rim brakes do not offer enough clearance for wide tyres, so in most cases, disc brakes are a necessity.
Bromptons For Tall Cyclists
Junik-HPV has extended the length of Brompton frames to better accommodate taller cyclists. Image: Junik-HPV
Brompton frames come in only one size, whether you’re 150cm/4ft11 or 200cm/6ft6 tall.
While you can get them to fit a taller rider by swapping a few components, best practice bike fitting requires frames to get longer as they get taller. This is not the case with a Brompton, as the distance from the saddle to the handlebars remains almost the same, no matter the height of the rider.
I might be a bit biased here as a two-metre (6ft6) tall cyclist, but I would love to see a new Brompton that’s scaled up for tall cyclists. Frame modifiers such as Junik-HPV have successfully extended the length of Brompton frames to appropriately accommodate tall customers.
There is no reason why Brompton couldn’t offer an XL frame size. Sure, it’d fold a bit bigger, but you can bet that tall cyclists would take a bigger fold over a cramped riding position.
Summary
Brompton is in a unique position where it can draw experience and design from the extensive knowledge of the Brompton aftermarket. Perhaps, the ultralight titanium Bromptons today would not exist if the product hadn’t been created by the aftermarket first?
There is clearly a demand for Brompton models that sacrifice folded size for slightly larger wheels. The 20 x 1.1″ wheel spec would be a great option for mile munchers, and the 18 x 2.0″ size would be perfect for those who want to take their bikes on bumpier roads. The frameset to accommodate these wheel sizes could even be the same.
It’d be great to see premium-level internal gear hubs as an option on Bromptons. These drivetrains are reliable and long-lasting and are already available on other folding bikes such as Bike Friday, Tern and Birdy. If Brompton wanted to be a bit different to the rest, the 6, 9, 12, and 18-speed Pinion gearboxes are very much an option they could pursue.
And belt drive would be the perfect drive option for any of these gearboxes.
I’ve analysed many of the top-tier bicycle gearboxes on this website, but have spent little time discussing the Shimano Alfine internal gear hubs that offer almost unbelievable value for money.
So, how good is a $199 Shimano hub? And should you switch from your derailleur gear system to an internal gear hub?
I will answer all of this and much more in this in-depth Shimano Alfine resource.
By the way, according to Shimano, it’s not pronounced Al-fine or Al-feen. It’s Al-fee-nay.
I’ve actually spent many years using and abusing Alfine hubs, including on a mountain bike that I built specifically for wet and muddy conditions. But over the last decade, I’ve been riding around the world on expensive Rohloff hubs. With a good handle on both gear systems, I’ll be drawing comparisons between these hubs throughout this presentation.
Advantages of Internal Gear Hubs
Internal gear hubs replace the derailleur gears on a bicycle, and you can actually remove your derailleur drivetrain from your bike and fit one up right now.
Internal gear hubs usually offer between 3 and 14 different gear ratios that are hidden inside a weather-sealed hub shell. As a result, you get a significant reduction in drivetrain maintenance, and with fewer components exposed to the elements, a reduction in running costs too.
For example, I’ve known Shimano hubs ($199) to have worked well for around 90,000km (56,000mi). Add in the nine chains ($63), six rear sprockets ($18) and three front sprockets ($33) that your drivetrain will wear through over 90,000km, and you’re looking at US $313 to ride more than twice the circumference of Earth!
Additionally, should you crash or drop your bike, there is no rear derailleur (or hanger) to put out of alignment, or worse, destroy.
Other nice features include the ability to shift gears while stationary, and the rear wheel can also be built stronger thanks to the shorter spokes and even spoke tension.
To cut down on drivetrain maintenance further, you can pair gear hubs with belt drivetrains. These drivetrains are cleaner, quieter and longer-lasting. In fact, they can last upwards of 30,000km. I’ve been riding belt drivetrains across multiple continents for over a decade, and have worn through just four belts in that time.
In terms of gear hub manufacturers, Rohloff and Kinderney make very expensive hubs that, in many circumstances, can outperform derailleurs. Sturmey Archer has manufactured IGH hubs for over a century, and Shimano is easily the biggest manufacturer of gear hubs on the planet.
The Shimano Alfine IGH
Shimano released their first internal gear hub in 1957 and has slowly built on their multi-speed hub designs ever since.
The Alfine series components come under the “urban” umbrella in Shimano’s product range, and they’re the highest-quality internal gear hubs that Shimano manufactures. You can get Alfine hubs with either 8 or 11 gears, and they are only compatible with regular 135mm dropouts (sorry, thru-axle frame owners).
These hubs offer unparalleled value for money. You can find the 8-speed hubs for less than US $200 and the 11-speed hubs under US $400. That’s significantly cheaper than a Rohloff 14-speed hub (US $1500).
The low cost of the Alfine products also translates into complete bikes that are very well priced. For about US $1000 or €1000 you can get an 8-speed bike with a belt drivetrain that’s fully decked out and ready to go.
Keep an eye out for bikes with Shimano Nexus 8-speed hubs too, as these hubs are virtually identical to the Alfine 8-speed with the exception of the brake types available.
So, what’s the difference between the 8-speed and 11-speed Alfine hubs?
Shimano Alfine 8 vs. Shimano Alfine 11
Gear Range
The gear range of the 8-speed hub is 306% and the 11-speed hub is 409%.
This simply means that the biggest gear ratio is 3.06x times bigger than the smallest ratio on the Alfine 8, and it’s 4.09x bigger on the Alfine 11.
With bigger gear ranges, we can pedal our bikes across a broader range of speeds, which is especially handy for pedalling downhill or with a stiff tailwind.
To understand this concept a bit better, let’s set the lowest Alfine gears so that they have you spinning the cranks at 60RPM at 8.4 km/h. The wider gear range of the 11-speed hub will allow you to pedal up to 57 km/h (100RPM) in the top gear, while the 8-speed hub will only take you up to 43 km/h.
Gear Steps
The numbers in the red box are the percentage difference in gear ratio when you change your gears.
Gear steps are the percentage difference in gear ratio when you change your gears.
A bike with smaller gear steps is particularly nice at higher speeds, as you can better fine-tune your gears to achieve the cadence (crank revolutions per minute) you’re most comfortable riding.
The Shimano Alfine 8 averages 17% gear steps across its gear range. To give you a sense of how this compares to a derailleur drivetrain, it’s a bit higher than a 1×12 mountain bike drivetrain (SRAM 10-52t, 15% gear steps).
In comparison, with the exception of the first gear (which is an unusually large gear step of 29%), the Alfine 11 averages a much smaller 13.5%. This is more like a 1×11 gravel bike cassette with 11-42 tooth sprockets (13% gear steps).
It’s worth noting that the 11-speed hubs offer consistent gear steps throughout their range. In comparison, the 8-speed hub has 14% to 22% steps between the gears, which means that gear changes won’t feel quite as predictable.
Lubrication System
When Shimano launched the 11-speed hub, they showed off the new oil bath lubrication system using a clear plastic hub shell.
The Alfine 11-speed hub operates inside an oil bath. The big advantage of this design is that it is hard for water and debris to make their way inside the hub shell.
The downside is that oil slowly leaks out of the side, so you will need to wipe everything down regularly.
In comparison, the Alfine 8-speed rolls on thicker greases and oils. This is a pretty fuss-free design, although if it’s not grease-packed appropriately for wet environments, water can and will work its way into the hub.
Drive Efficiency
This chart shows the drive efficiency of different internal gear hubs. The percentage on the y-axis shows hubs can be as low as 78% efficient and as high as 97%. Image: FahrradZukunft
Both Shimano Alfine hubs achieve around 90% drive efficiency on average.
This is approximately 5-7% less efficient than a clean and well-lubricated derailleur drivetrain. But note that this doesn’t mean you’ll be 5-7% slower on an Alfine bike – when you do the maths, it’s close to 2%, or a minute per hour when compared to a well-lubricated derailleur drivetrain.
That said, in poor weather conditions, the Alfine hubs can work out more efficiently, as there are fewer places in the drivetrain for mud and debris to get caught.
Shimano Alfine Hub Weight
This English Cycles Alfine build is under 8kg.
The Alfine gear hubs both weigh around 1700 grams (3.75lb) while regular rear bike hubs are often under 500 grams (1.1lb).
It might sound like an Alfine hub will add a significant amount of weight to a bike, but when we peg Alfine bikes against derailleur bikes at similar price points, we often end up with a weight penalty of less than half a kilogram (<1.1lb).
The lightest Alfine bike I’ve ever seen was just 7.6kg (16.7lb) – it’s pictured above.
Shimano Alfine vs. Rohloff Speedhub
The Rohloff hub is considered the gold standard of internal gear hubs – literally, in the case of this one-of-two 24 Karat gold hub.
Rohloff hubs are generally considered the gold standard of internal gear hubs as they are built incredibly well and experience very few failures.
They also offer 14 gears across a 526% gear range, which is about the same as a modern mountain bike drivetrain (1X drivetrain with a 10-52T cassette). In addition, they’ve been tested to be around 4% more efficient than the Alfine hubs across the gear range.
There is even a guy out there who has cycled 430,000km on a Rohloff hub, which is about five times the life expectancy of an Alfine hub.
Rob English’s custom Alfine commuter bike.
These are all great characteristics, but the Shimano Alfine hubs are actually better in a number of ways. In fact, on balance, I think the Alfine is the best hub for most people.
So, what’s better about the Alfine hubs?
The biggest reason for me is that they run significantly quieter, especially in the lower gear ratios. The Rohloff hub is particularly noisy in gears 5, 6 and 7.
The price is more than US $1000 less than a Rohloff setup, resulting in a great price-to-performance ratio.
Alfine hubs are built around a trigger shifter, which many people prefer over Rohloff’s twist shifter design.
You can use some Alfine hubs with electronic shifters that will complete perfect shifts every time as there is no cable housing that can be affected by grime or grit.
Alfine hubs also tend to be better for drop-bar bikes as they’re compatible with various aftermarket shifters or the Shimano Di2 electronic shift levers.
Shimano Alfine Electronic Shifting
Ok, I’ve just mentioned that Alfine hubs are excellent thanks to their electronic shifting, so let’s take a closer look at these components.
You might be thinking that Di2 electronic shifting is a bit of a gimmick, but when you understand how Alfine hubs shift, it can definitely be worthwhile.
This is because it’s the shifter that controls the alignment of the planetary gears in an Alfine hub. That means that improper cable adjustment and dirty or damaged cables can prevent the hub’s internal components from engaging properly, which can result in gear slipping, grinding, or worse – internal components breaking inside the hub and making a mess of things.
Electronic shifters make perfect shifts every time, ensuring you do not damage anything inside the hub from improper cable maintenance. Out of the two Alfine hubs, electronic shifters make the most sense on the 11-speed model, as the cable adjustment is especially sensitive.
It’s worth noting that you cannot upgrade Alfine hubs from a mechanical shifter to an electronic shifter. The Di2 hub design is different.
Electronic shifters are also nice on drop-bar bikes, as you can easily pair them with Shimano hydraulic brakes for an ultra-low-maintenance brake setup too. Additionally, the Di2 drop bar levers can be programmed in a number of ways. You can change the buttons so that your left-hand shifts down and your right-hand shifts up. And you can hold the buttons and shift multiple gears at once.
How Do Shimano Alfine Hubs Feel In Comparison To Rohloff Hubs?
I’ve used and abused a number of Alfine and Rohloff hubs, including on this ride through Peru.
In terms of ride feel, the Alfine hubs are ‘spongy’ compared to Rohloff hubs due to the use of roller clutches inside the hub.
You can actually see how much forward movement there is in the hub when you step on the pedals from a stationary position. When riding, this is only noticeable if you mash your pedals at a slow cadence. It’s not at all noticeable at higher cadences.
The gear steps are quite similar between the Rohloff and Alfine 11 for the most part (13.6%). The thing you might miss is the extra-wide gear range of the Rohloff (526%).
The shifting on Alfine hubs is incredibly fast when the shift cable and cassette joint are running perfectly. But when either of these components gets muddy or gritty, shifting is not as instantaneous as a Rohloff hub. The Rohloff holds the advantage here as the gear indexing is inside the hub, rather than from the shifter.
Are Shimano Alfine Hubs Suitable For Touring & Bikepacking?
Specialized once built a touring bike called the AWOL Transcontinental. These days, there are few touring bikes with Shimano Alfine hubs.
You will find lots of people who have successfully completed bike trips on Shimano Alfine hubs. In fact, the around the world record was once set on a Shimano Alfine 8-speed hub!
But there are two things that prevent me from recommending Alfine hubs to all bike travellers. Please note that these ‘issues’ do not apply to everybody in every situation.
Low Climbing Gears
Low climbing gears are important for bicycle touring as they allow you to ride up hills at a sustainable effort with all of your luggage. When your climbing gear is too high, you’ll be working much harder than necessary, which results in more muscle fatigue, and frankly, makes hills much less enjoyable.
Ultimately, the Alfine hubs are optimised for urban use, which usually means getting around town on flatter terrain.
Shimano’s lowest recommended gear ratio on the Alfine hubs is 1.8:1 (11-speed) and 2:1 (8-speed). When we calculate the climbing gear that this yields in “gear inches”, it’s simply not low enough for most bike travel. And it’s not by a little bit either; the first gear on the Alfine is about the same as my fifth gear on my Rohloff bike (27 to 30 gear inches).
Riding up steep hills with an Alfine either requires more power output or a lower pedalling cadence, both of which will tire you out faster.
Reliability, Spare Parts & Repairs
For touring, another thing an internal gear hub needs to be is reliable. This is absolutely paramount. Getting an Alfine hub fixed can waste a lot of time, potentially ruining a trip.
Now, Alfine hubs are often very reliable, especially the 8-speed model. But it’s still not uncommon to hear of people having problems with them.
I wouldn’t be too concerned about servicing and spare parts in the UK or Europe, as internal gear hubs are common, and you are often close to a bike shop that can help. In the US, it’s probably ok too, as long as you’re happy to ship your wheel to a gear hub specialist. But in the more remote parts of the world, you should be prepared to ship your wheel internationally for a repair.
You could say the same thing about a Rohloff hub, but with their track record for reliability, it’s a very safe bet.
How To Increase Shimano Alfine Hub Reliability
Ok, let’s now talk about maintenance and damage prevention.
Shimano Alfine hubs are low maintenance, but they are not zero maintenance. Here are three things you can do to keep your Alfine hub reliable for many years to come.
Shift Cable Maintenance
If you learn how to tune the Alfine gears and maintain your cables, you will likely have no problems with your hub.
In the electronic shifting section, I discussed in detail why cable maintenance can prevent gear slipping, grinding, or internal components from breaking inside the hub and making a mess of things.
As the 11-speed hubs are much more sensitive to cable adjustment than the 8-speed hubs, you will need to keep a closer eye on its shift components.
Make Careful Gear Shifts
Regarding gear shifting, it’s best practice to ease your pedal power momentarily when you change gears. I’m talking just a fraction of a second! This is because you can damage your hub by putting high loads into the internal components before the shift is 100% complete.
Check lubrication
As the oil slowly seeps out of the Alfine 11-speed hubs, you will need to conduct regular oil changes. The first oil change is the most important one, and it’s after just 500km. After that, it’s every two years or 5,000km.
If you’re using the 8-speed hub in wet and gritty conditions, make sure to get the hub re-greased every year. The grease helps to keep water and grit out of the hub and will vastly improve the life of the hub.
Lowering The Recommended Gear Ratio
A Genesis Fortitude Alfine fitted with a 30/22 gear ratio (21 gear inches). Image: Andy Cox
I discussed the issue of low gear ratios and Alfine hubs previously. But some users have reported using ultra-low gear ratios (eg. 24t front, 20t rear) to achieve a similar climbing gear to my touring bike – and with no problems at all.
But I’d be careful here, especially if you’re a heavier and more powerful rider.
With an ultra-low gear ratio (1.2:1), a 100kg/220lb rider can stand on the pedals and put 143Nm into an Alfine hub, which is more than the maximum input torque that Rohloff allows (130Nm) – and that’s a hub rated for tandem use.
A table showing the minimum gear ratios you could use with a Shimano Alfine hub (and still keep the input torque under 100Nm).
Rider weight is critical for maintaining a low input torque. With a 1.2:1 gear ratio, a 50kg/110lb rider only puts 72Nm into the hub when standing on the pedals. But if an 80kg/176lb rider did the same thing, they would put 115Nm into the hub, increasing the chance of internal damage.
Here’s a table I made that shows the minimum gear ratios one could use without exceeding 100Nm of torque. But use it at your own risk, and please don’t tell Shimano.
Are Shimano Alfine Hubs Reliable?
The name Alfine is derived from the phrase “Always Fine”, but a quick search online reveals endless forums with examples of Alfine hubs that didn’t do their job.
The main culprit is the Alfine S700 11-speed hub that was in production between 2010 and 2017. Oil leaks were a-plenty, the cassette joint sometimes had manufacturing defects, and if the shift cable was not adjusted correctly, internal damage was much more probable.
The latest S7001 11-speed hubs employ six new internal components that were re-designed to prevent damage, but these hubs do still leak some oil that periodically needs to be wiped off the hub.
The Alfine 8-speed hub is considered to be the most durable option of the two.
Shimano Alfine & Electric Bikes
The S7001-series Alfine hubs are rated for eBike use, but be careful, as the maximum torque of the motor will need to be on the low side.
While there is no official torque rating for the Alfine hubs, the STEPS E6000 internal gear drivetrain comes with a 50Nm motor, so we can assume it’s about that.
Speaking of the STEPS internal gear drivetrains, they’re super cool! The Alfine 8 Di2 (or Nexus 5E Di2) hub will automatically change gears for you based on your speed, cadence and torque.
Summary
Shimano Alfine hubs are excellent, and for many people out there, I think they’re actually a better option than a Rohloff hub. This is because they’re cheaper, quieter and employ trigger or neat drop bar shifters. I especially like the drop bar electronic shifters.
With an Alfine-equipped bike, you will enjoy just how easy, cheap and low-maintenance an internal gear drivetrain is. Better yet, pair an Alfine hub with belt drive and enjoy a grease-free and long-lasting drivetrain for years to come.
I recommend the 8-speed version for a simple grocery-getter or for someone who simply just wants a bike that works. For someone who rides a bit more seriously, the 11-speed version offers smaller and more predictable gear steps, along with a wider gear range.
I don’t usually recommend Alfine hubs for touring and bikepacking due to the climbing gear ratio that’s too high, and the fact that mechanical failures are not unheard of. This is where a long-lasting and robust Rohloff drivetrain clearly wins out.
But if you ride flatter trips and keep on top of the shift cable maintenance, Alfine hubs work out great.
The Effigear Mimic is an exciting new addition to the growing range of bicycle gearboxes.
You might not have heard of this small French gearbox manufacturer before, but they’ve actually been in the gearbox game for around a decade.
The Effigear Original was larger in size than the Pinion P1.18 gearbox, it had a smaller gear range and fewer gears. While Pinion began by pushing their 18-speed gearbox drivetrain into the touring and urban bike markets, Effigear was forging their own path into the mountain bike world with just nine gears.
And this was for good reason.
Unlike other gearbox systems, the Effigear Original had a separate output drive sprocket from the crank assembly. Image: Cavalerie Bikes
Unlike the Pinion gearbox, Effigear had its drive sprocket located separately from the crank assembly. This allowed full-suspension frame designers to build their swingarm pivots around the upper axle of the gearbox, creating a simple and silent drivetrain (with belt drive) but also reducing the effect of chain forces on the rear suspension (this is known as ‘pedal kickback’).
The downside to building frames around a large-volume gearbox is that it significantly restricts what frame designers can do with their linkages, which largely determines the ride characteristics of a full-suspension bike.
The Starling Spur is wonderfully simple in its design. Image: Starling Cycles
Instead of waiting for bike manufacturers to adopt their gearbox design, Effigear actually created their own bike brand, Cavalerie Bikes, to showcase the potential of their drivetrain.
While a few brands did adopt the gear system (notably Nicolai and Starling Cycles), Effigear gearboxes have remained very niche over the last decade as a result of the gearbox packaging.
But that’s all about to change.
The New Effigear Mimic Gearbox
The new Effigear Mimic in all its glory.
The Effigear Mimic uses a much more compact design than the Original, which provides more flexibility when it comes to frame design.
You’ll find nine gears inside the gearbox, with the equivalent range (469%) of a 1X drivetrain using an 11-50 tooth cassette (455%).
As the output sprocket has been moved to the crank assembly, the weight has also been reduced by 15% compared to the Original design, making it competitive with Pinion’s 9-speed gearbox.
Effigear stickers are used for the prototypes but the branding will be laser etched on the production units.
In fact, the Mimic will now install to the same frame plate as a Pinion gearbox (it’s an open design). As the Pinion frame plate is used by over 100 bike manufacturers, Effigear can now sell its gearboxes to a much larger market.
This means we finally have a choice of crankset gearboxes too (and there’s another budget gearbox in the works).
Before we dive into the defining features of the Effigear Mimic, let’s discuss why gearboxes are a fantastic drivetrain for some bikes.
Why Gearbox Drivetrains Are Great
Inside the new Effigear Mimic gearbox.
1. There’s much less maintenance. Gearboxes don’t ever need to be adjusted and there are just two sprockets to clean. The gears themselves are sealed away and impervious to mud, grit, snow and sand. All you need to do is periodically drain the oil and fill it back up.
2. The components are less susceptible to damage. With no exposed derailleurs, delicate hangers or brittle cassettes, you can stress less about rocks, sticks and the aftermath of your crashes. I also love travelling with gearbox bikes as the drivetrains cannot get damaged by baggage handlers.
3. There are fewer wear items. The gearbox is designed to last 100,000km and the external chain and cog wear at a significantly reduced rate compared to a derailleur system.
4. The straight chain line. The chain line on an Effigear drivetrain is perfectly straight, resulting in less chain wear. This equates to a longer chain life; expect more than 10,000km.
5. It’s belt drive compatible.Belt drivetrains can last more than 30,000km, are silent, lightweight and require very little cleaning and lubrication.
The Effigear Mimic is being marketed to both mountain bikers and gravel riders. Image: @batiste.nos
6. There are instant gear changes. You can make gear changes without pedalling, and you can even shift up to the harder gears at max power. You will need to back off on your power for a fraction of a second when shifting down though.
7. There’s less unsprung mass at the rear wheel. On full-suspension bikes, the rear swingarm can respond quicker to ground forces when there is less weight at the rear wheel, offering better small bump sensitivity.
8. The stronger rear wheel. As the hub doesn’t need to accommodate for a cassette, the flanges are spaced wider, which results in extra wheel strength and durability thanks to the larger bracing angles and more even tension across the spokes.
Now that I’ve got you all stoked on gearboxes, let’s discuss the features unique to the Effigear Mimic.
Key Feature: Variable Gear Steps
Gear steps are the percentage difference in gear ratio when you change your gears.
A bike with smaller gear steps is particularly nice at higher speeds, as you can better fine-tune your gear ratios to achieve the cadence (crank revolutions per minute) you’re most comfortable riding.
Smaller gear steps work out to be much less necessary at lower speeds, as your speed changes very little for each shift (1-2kph).
To squeeze the most out of any gear range, a drivetrain ideally starts with big gear steps in the easier gears, and ends with small gear steps in the harder gears. This is exactly how derailleur drivetrain manufacturers design their cassettes.
Currently, top-tier gearboxes like Pinion, Rohloff or Kindernay use uniform gear steps from the first gear to the last. In comparison, the Effigear uses variable steps that mimic a regular cassette.
Effigear Mimic Gear Steps
Box Components Cassette (11-50t)
Gear 1-2
28%
19%
Gear 2-3
24%
24%
Gear 3-4
22%
21%
Gear 4-5
19%
27%
Gear 5-6
19%
22%
Gear 6-7
21%
20%
Gear 7-8
21%
15%
Gear 8-9
17%
18%
Average Gear Step: 21%
Average Gear Step: 21%
As you can see, the lower gears on the Effigear Mimic have bigger gear steps, while the higher gears use smaller gear steps. This is not dissimilar to the Box Components Prime 9 cassette.
The Effigear Mimic comes with SRAM Rival levers for an extra €139.
Another big drawcard for the Effigear Mimic is that it uses SRAM flat bar or drop bar shifters (with a modified pull-ratio to suit the gearbox). These styles of shifters are often preferred over the typical twist shifters that come with most gearboxes.
You can upgrade a Pinion gearbox to trigger or drop bar shifters, but it’s not cheap. Cinq aftermarket shifters on a flat bar bike add €300 to the purchase price, and for a drop bar bike, expect to add €600.
Effigear has said they’re working on adapted Campagnolo shifters too, should you have a preference for Italian lever shapes.
Key Feature: 48 Engagement Points
This Effigear Mimic is mounted to a Zerode Taniwha. Image: @batiste.nos
Gear pickup determines how quickly your drivetrain engages when you start pedalling.
On most bikes, you’ll notice a small clunk when you apply power to the pedals at low speeds, which is usually the pawl system in your rear hub engaging. Ideally, we want instant engagement, but bike hubs usually offer between 24 to 36 engagement points per wheel revolution.
Gearbox bikes have a second freewheel built into the gearbox itself that needs to engage along with the hub, slowing the gear pickup time further.
The number of engagements varies between gearboxes. Pinion gearboxes offer between 14 and 22 engagement points depending on the gear selected, so even with a high or instant engagement rear hub, there is still a noticeable delay at low speeds.
In comparison, the Effigear Mimic gearbox has 48 engagement points in every gear, which means it’ll engage just as quick as most bikes.
Effigear Fixed Gear Hub
An even faster way to engage the rear wheel is with the optional Effigear fixed gear rear hub!
This results in the chain or belt constantly moving with your rear wheel, which could be an issue should a rock or stick jam into your sprockets. That said, Cavalerie Bikes have been using fixed gear hubs for many years now, so perhaps it’s not a problem in practice.
Also, note that a continuously spinning chain or belt will experience more wear.
Effigear Mimic vs. Pinion C1.9XR
The Effigear Mimic and Pinion C1.9XR gearboxes match up pretty closely in terms of specs.
Let’s find out the key differences:
Effigear Mimic
Pinion C1.9XR
Number of Gears
9
9
Gear Range
469%
568%
Gear Steps
21% (Variable)
24.3% (Even)
Engagement Points
48
14-22
Chainline
TBC
54mm
Q-Factor
177mm
166mm
Upshifting Under Load
Yes
Less force in 3-4 & 6-7
Downshifting Under Load
Less force required
Less force required
Max Input Torque
250Nm
250Nm
Gearbox Weight
~2kg/4.4lb
~2kg/4.4lb
Oil Capacity
60ml
60ml
Oil Change Interval
5000km or 1-year
10,000km or 1-year
Warranty
Five Years
Two Years
Place of Manufacture
France
Germany
Production
2021-Current
2016-Current
The key differences:
The gear range and gear steps are bigger on the Pinion C1.9XR, so it will be better suited to steeper terrain or for eBike use where you experience quicker acceleration.
The distance between the pedals (q-factor) is 11mm narrower on the Pinion gearbox, which might be preferred on a road, gravel or commuter build.
You need to back off on the power when shifting up in gears 3-4 and 6-7 on the Pinion. In comparison, the Effigear will upshift under a full load in all gears.
The Pinion gearbox requires less frequent oil changes.
The warranty is three years less on the Pinion. That said, Pinion have also had their gearbox in production for five years now, which will have ironed out any issues.
Effigear Mimic Price
When I add all of the components required to complete a gearbox drivetrain*, the Effigear Mimic is a touch cheaper than the Pinion C1.9XR and slightly more expensive than the new Kindernay VII.
*To make this a fair comparison, I’ve made sure all drivetrains include a crankset, front and rear sprockets, a rear hub, a shifter and cables.
Effigear Mimic Drive Efficiency
Like all other gearboxes, the Mimic will transfer less of your pedal power to the rear wheel than a derailleur drivetrain in perfect riding conditions. This is simply because there are two sets of cogs that are always meshing together inside a gearbox, as well as oil moving between them.
But the type of riding conditions is key here.
In poor weather conditions, there is likely an efficiency advantage to using a gearbox system as the exposed part of the drivetrain has fewer moving parts and crevices for mud and debris to get clogged in.
While we don’t have any data on the Effigear Mimic, we do know that a Pinion gearbox with similar straight-cut gears loses an average of 6.5% across the drivetrain compared to a single-speed chain set up in a laboratory (200-watts power output).
And compared to a derailleur drivetrain, we can expect the Mimic to be around 5% less efficient in perfect conditions.
Is Electronic Gear Shifting Coming?
Effigear posted a video last year on their social media showing smartphone-controlled electronic shifting. While it’s very early days, this might give us a glimpse into what Effigear are currently working on.
What About eBikes?
The Valeo Smart eBike System combines an Effigear gearbox and motor in one.
It’s worth noting that Effigear is also manufacturing an eBike-specific gearbox with a built-in motor!
Interestingly, the Valeo Smart eBike System uses seven-speed gearing with automatic gear changes, which will be perfect for urban use but might not be ideal for off-road use (this really depends on the software). For mountain bikers, there will be two buttons you can use to shift manually.
A cool thing is that the Smart eBike System will reduce motor torque when shifting, which allows you to downshift under load too!
Expect to see the Valeo/Effigear gearboxes on eBikes early next year.
Summary
I’m very excited to see a new gearbox on the market – fingers crossed the Effigear Mimic proves as reliable as other systems.
While the specs are very similar to the Pinion C1.9XR gearbox, the Mimic offers variable gear steps, additional engagement points, shifting under load in all gears, SRAM shifter compatibility and a longer warranty.
Pinion gearboxes, in comparison, offer a narrower distance between crank arms, longer oil change intervals, and multiple options in terms of the number of gears and gear range. Additionally, Pinion has had more time to sort out any manufacturing and design issues given they’ve been in production for five years now.
If you’re not that enthusiastic about the additional weight of most gearbox drivetrains, perhaps the new Kindernay VII internal gear hub will pique your interest.
This new 7-speed version of the Kindernay gearbox is within a few hundred grams of a 1X drivetrain, it’s more efficient than ever, and it has fewer internal components.
In this article, I’ll first bring you up to speed on the original Kindernay 14-speed hub. We’ll then compare the 7-speed at 14-speed versions, and later, we’ll discuss some of the practical implications of using a hub with fewer gears.
What Is The Kindernay Hub?
The Kindernay XIV can be set up for a fat bike wheel or a regular wheel. Image: Terrengsykkel.no
Kindernay burst onto the gearbox scene in 2016 when they showed off a prototype 14-speed internal gear hub that could replace the derailleur gears on your bike.
Like other planetary gear hubs, the Kindernay promised a long-lasting drivetrain with less maintenance, zero gear adjustment, instant shifts, and components that are less susceptible to wear and damage.
There were a few defining features of the Kindernay XIV:
The gearbox was separate from the hub shell. As you can see in the image above, the gearbox slides into a separate hub shell. A big advantage of this modular design is that you can have one expensive gearbox that swaps between multiple bikes. For example, you could have a mountain bike that houses your Kindernay year-round, but another hub shell built into a fat bike wheel that you only use in winter. The time it takes to switch the gearbox between bikes is about the same as fitting a new tyre – so it’s not quite ideal for swapping between bikes you use regularly.
It was using a hydraulic gear shifter. By using hydraulic shift lines, shifting speeds were quicker, and debris could not work its way into the cables, affecting shifting performance. It also allowed a simple way for Kindernay to use thumb shifters instead of a twist shifter found on other gearbox systems.
It was designed for 12mm thru-axles. Most gear hubs are quick release (or bolt-up) and are not compatible with modern thru-axle bike frames (the Rohloff A12 is the exception). The Kindernay was designed specifically for 12mm axles and can be stepped down for quick release too.
It was lighter than the competition. The 14-speed Kindernay hub fitted to a bike was 365 grams (0.8lb) lighter than a 14-speed Rohloff hub.
It had a higher torque rating than other internal gear hubs. The Kindernay was rated up to 160Nm, which is 30Nm higher than a Rohloff hub.
It had a wider gear range than other internal gear hubs. The 14-speed Kindernay had the widest gear range of any hub available (it still does) at 543%, which is a touch wider than the Rohloff (526%).
After a few more years in development, production units of the Kindernay XIV began shipping in 2019.
Kindernay 7-Speed vs. Kindernay 14-Speed
The Kindernay VII uses a black gearbox instead of silver found on the XIV.
Kindernay VII 7-Speed: + 250 grams lighter + 250 euros cheaper + Even more efficient (there’s no ‘reduction gear’, it’s the equivalent efficiency of gear 8-14 on the XIV) + Optional hub housing for 6-bolt brake rotors (not pictured) + Available in black
Kindernay XIV 14-speed: + More gears (obviously) + Wider overall gear range + Smaller steps between each gear + Available in silver
The New Onesie Shifter
The Onesie shifter will neaten up the bars of a mountain bike compared to the Twosie model.
Kindernay has also released a second shifter called the Onesie, which importantly, can be used with both the 7-speed and 14-speed hubs.
You can change one gear at a time, or multiple gears by pushing the lever a little further (see the Onesie in action HERE).
While some will prefer the more compact form factor of the dual-sided shifters (Twosie), mountain bikers often need space on the left-hand side of their handlebars for dropper post levers or suspension lockout switches. The Onesie keeps that space free.
Kindernay VII Actual Weights
I’m using my Nukeproof Mega’s drivetrain to determine the weight difference between the Kindernay VII and a 1X drivetrain. This is because I may or may not be planning to upgrade to a Kindernay VII and am curious about the weight difference!
Shimano Deore 12-speed Rear Derailleur
319 grams
Shimano Deore 12-speed Shifter (With Cable)
195 grams
Shimano Deore 12-speed Cassette
595 grams
Sun Ringle SRC Rear Hub (12×148)
340 grams
Total Drivetrain Actual Weight
1449g / 3.2lb
Kindernay VII Gearbox
1193 grams
Kindernay 32H Hub Shell (28H is 101g, 36H is 130g)
127 grams
Kindernay Brake Adapter, Torque Arm, Lockring
49, 35, 5 grams
Kindernay Onesie Shifter (With Cables, Oil)
302 grams
Kindernay 20T Sprocket
69 grams
Kindernay Chain Tensioner (necessary for full suspension bikes)
121 grams
Total Drivetrain Actual Weight
1896g / 4.2lb
This weight comparison isn’t entirely fair due to the price discrepancy between a Shimano Deore 1×12 drivetrain (€244) and the Kindernay drivetrain (€1065), although when you factor in the running costs over time, the price difference will be less significant compared to any derailleur drivetrain.
In any case, let’s instead use a SRAM XX1 AXS drivetrain with a DT Swiss 350 hub (€1011, 1107 grams) to better match the pricing. The weight difference is now 750 grams (1.65lb).
A fairer comparison might even be to match the gear range, number of gears, and price. This would require the 14-speed version of the Kindernay hub, which jumps up to 2096 grams. In this comparison, the weight difference is closer to 1 kilogram (2.2lb).
The shorter chain and spoke length on the Kindernay bike will pull a little weight back. But depending on your current drivetrain and whether you need to fit a chain tensioner, expect the Kindernay VII to add between 200 and 1000 grams to your bike.
Kindernay VII Gear Range
The gear range of the Kindernay VII is 427%. This simply means that the biggest gear ratio is 4.27 times bigger than the smallest.
With a bigger gear range, we get gear ratios that allow us to pedal across a broader range of cycling speeds.
Here’s how the VII compares to other drivetrains: Kindernay 7-speed – 427% 1X XT drivetrain – 510% Rohloff 14-speed hub – 526% Kindernay 14-speed hub – 543% 2X XT drivetrain – 623% Pinion 18-speed gearbox – 626%
The Kindernay VII clearly has a smaller gear range than most off-road drivetrains. Whether this is a problem or not will depend on your typical cycling speeds.
If we set the lowest gear ratio on the Kindernay VII so that you’re pedalling at 5kph up a hill (60RPM), the highest gear will have you ‘spinning out’ at 43kph (120rpm). In comparison, the top gear of a Shimano Deore 1X drivetrain would have you spinning out at 51kph (120rpm).
Gear steps are the percentage difference in gear ratio when you change your gears.
A bike with smaller gear steps is particularly nice at higher speeds, as you can better fine-tune your gears to achieve the cadence (crank revolutions per minute) you’re most comfortable riding.
Most 1X drivetrains for mountain bikes have an average gear step of around 16%. The Kindernay VII? It has very large 28% gear steps due to its relatively wide gear range for a 7-speed hub.
Every time you shift gears using a 14-speed Rohloff hub, your cadence changes by approximately 11RPM.
Gear steps are a bit abstract, so I will now use cadence differences to illustrate what 28% gear steps mean for you.
The graph above shows the range of speed for each gear between two selected RPMs. In the case of the Rohloff hub, whenever you shift gears, your cadence will change by 11RPM. If you’re in the 6th gear and pedalling at 90RPM, by switching to the 7th gear, you will now be pedalling at 79RPM.
In comparison, the Kindernay VII will require a cadence change of 20RPM per shift. Whether this suits you will depend entirely on the terrain you ride.
As you can see in the graph above, the speed range between two cadences gets wider as you go faster. This means that maintaining your preferred cadence will be harder to achieve at higher speeds, and easier to achieve at lower speeds.
To illustrate this, let’s say you were riding at 30kph (90RPM) using the Kindernay VII. If you switched up a gear, it wouldn’t be until 38kph when you’d hit 90RPM again. You essentially have to ride at 30 or 38kph if you want to maintain your preferred cadence.
The differences aren’t as dramatic at low speeds. At 8kph (90RPM) in the first gear, you’d hit 90RPM in the second gear by 10kph.
In short, the 28% gear steps will be totally fine for steep mountain bike trails where you spend a lot of time climbing slowly or descending fast. However, they might be frustrating on long flat roads. If you ride the latter, you’ll be better off with the Kindernay XIV hub, which uses 13.9% gear steps instead.
Kindernay VII and eBikes
A Specialized Kenevo enduro eBike might be the perfect use case for the Kindernay VII hub.
It’s worth noting that big gear steps work particularly well on eBikes.
This is because electric bikes accelerate much faster than regular bikes, so riders will often find themselves shifting two or more gears at a time. SRAM has recognised this as a problem on eBikes and makes a cassette called the EX1 with 24% average gear steps.
Due to the higher overall bike weights and power assistance, the added weight of a Kindernay hub works out to be less significant on an eBike too.
Summary
The Kindernay VII looks like a great addition to the range.
Due to the larger gear steps, I suspect it will prove popular on gravity-focussed mountain bikes and eBikes. For those who need the bigger gear range, or simply prefer smaller gear steps, the Kindernay XIV will better fulfil your needs.
I can’t wait to fit a Kindernay VII to my enduro bike! I’m interested to find out how the extra 300 grams of unsprung mass affects the suspension performance, whether I notice a suspension performance gain from the lack of derailleur clutch, and how the 28% gear steps will work on my local trails.
The Kindernay VII is available in Q3 2021 and if you’re heading to Eurobike, you can meet the Kindernay crew at Hall B1, Stand 505. The Kindernay website is HERE.
Bicycle gearboxes have been around for almost a century, but it’s only recently that they have truly proven themselves as a worthy alternative to derailleur gears.
Gearboxes trade a small amount of drive efficiency and weight, in order to achieve a significant reduction in maintenance and component wear, as well as a higher performance in poor riding conditions.
Additionally, you can pair gearboxes with belt drive, which eliminates chain cleaning and lubrication, and allows you to pedal over 30,000km before replacing any parts.
Zerode makes gearbox mountain bikes complete with belt drivetrains.
These days you can find gearbox bikes that will cross continents, complete your daily commute or slay mountain trails.
Right now, you’re probably thinking gearboxes are pretty cool, and I agree. But have you ever thought about building your own? Like, at home with old cassette cogs and chains and plexiglass…
https://youtu.be/5oD-oVlTtcw
Well, champx (a user on Instructables) did just this. And today, I’ll be showing you both how this homemade gearbox works, and how it was constructed.
The Bicycle Gearbox Plans
The plans and calculations had to be finished before construction could start. Image: Instructables/champx
The first step was to put the idea on paper.
The inspiration for the design was based on a lawnmower gearbox, which uses a similar gear selector but differs a little when it comes to the use of spur gears rather than chain and sprocket gears.
Champx first ran the numbers to determine the gear ratios and drivetrain parts that were required to make the gearbox work. Once the sprocket sizes were found, the concept was turned into a set of plans, which were drawn to scale.
From an idea floating in his head to having a full set of plans, it took champx just two weeks.
How Does The Gearbox Work?
I’ve drawn up a basic diagram to show how the gearbox works. Follow the arrows!
If you’re scratching your head and trying to understand how it works, it’s time to listen up (my explanation will make the most sense if you watch my video on this gearbox).
Looking down at the gearbox from above, we can see the crank arms as well as the bottom bracket axle. The picture above on the right side should give you a sense of orientation.
The force from the pedals travels inside the gearbox to a gear selector, which slides along the axle and allows you to engage one of three different gear ratios. The first gear provides the lowest drive ratio and the third gear the highest.
Your pedal power now travels via one of three chains to the next set of sprockets on a separate axle, which then turns a sprocket on the opposite end. All four of these cogs are welded to the axle, which means that all four chains inside this gearbox spin when you pedal.
The chain on the right-hand side then connects to one last sprocket inside the gearbox. This sprocket is attached to the external sprocket, meaning they both spin at exactly the same rate. Importantly, these two sprockets are decoupled from the axle, allowing the external sprocket to spin faster or slower than your cranks. I’ll show you a video demonstration of this shortly.
The external sprocket then goes on to drive the rear wheel.
How Was The Bicycle Gearbox Made?
Special rings were machined to fit the old cassette cogs to the axle. Image: Instructables/champx
Hopefully, you now have a good understanding of what’s going on inside this gearbox. Let’s now take a look at how it was constructed.
The first thing that champx made was the bottom bracket axle and gear selector. Special rings with internal notches were machined with a mortiser, and attach the cassette cogs to the axle. The notches inside the rings allow the gear selector arm to engage the desired gear.
The sliding gear selector was installed on the bottom bracket axle. Image: Instructables/champx
The axle was later hollowed out so that the spring-loaded gear selector would fit inside. To prevent corrosion from affecting the gear selector’s ability to slide, it was made from brass – hence the gorgeous gold colour.
With the hardest bit out of the way (machining parts), champx made a test rig to try out his concept. The secondary axle was assembled with the four necessary cassette cogs, which are all welded to the axle.
The four chains were then hooked up, and the rig was ready to test.
https://www.youtube.com/watch?v=H-GNa7iwXr0
If you watch the red striped tape on the right-hand side of the axle, you can see it spinning at different speeds when each gear is selected.
Champx now needed to make the box part of the gearbox. He chose to use stacked together sheets of plexiglass so that you could see the sprockets spinning inside!
A friend machined the bearing locations into the outer sheets, but otherwise, champx used a jig saw and hole saw to shape the plexiglass, which is no easy feat.
With the gearbox coming together nicely, the next step was to make it look pretty. Champx worked his way from coarse to fine-grit sandpaper to give it that glassy look.
The box wasn’t quite wide enough, so one more 6mm sheet of orange plexiglass was added. This turned out to be the cherry on the top, and ties in really nicely with the orange chains.
The remaining shifting components now needed to be added to the gearbox.
The remaining shifting components were installed to the outside of the gearbox. Image: Instructables/champx
Inside, you can see a small red rotating “hand” (shown in the video at 5:05) that pushes the gear selector to the left and right. This connects to a rod outside the gearbox, which is lifted up and down using a spring-loaded cable.
Unfortunately, the original spring mechanism didn’t provide enough cable tension, so champx built a heavy-duty version that works well.
The Completed Gearbox Bike
The finished gearbox is installed in a custom-made frame! Image: Instructables/champx
With the gearbox now complete, it was time to build a bicycle frame to house it.
Given the novelty of this project, it made sense to build the gearbox into a fun bike!
Champx welded up a frame that he calls the “Swing Monster”. This cruiser-style bike uses headset bearings at both the fork and seatpost, so that it can steer from the front or rear wheel.
I say, mission accomplished on this project! The bike looks amazing and would be a fun challenge to ride too.
Summary
The “Swing Monster” gearbox bike out on a test ride. Image: Instructables/champx
As a bike nerd, tinkerer, gearbox aficionado and lover of cool projects, I had to share this work!
I hope it inspires some of you to build something that’s normally out of your comfort zone.
If you know of some more out-of-the-box DIY bicycle projects, I’d love to hear about them in the comments.
