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There are many comfort solutions for the rear of a gravel bike but we have surprisingly few for the front. In terms of aftermarket components, there are the Redshift ShockStop and Kinekt Suspension stems which do an incredibly effective job of reducing vibrations.
But what about a gravel suspension fork?
I was very curious about the Lauf Grit SL suspension fork. This leaf-sprung fork has a truly unique construction that is polarized not only by its looks but also by its price.
And thanks to Lauf, I will be testing the Grit SL fork to see if it’s the real deal or just an overpriced gimmick.
What is the Lauf Grit SL Suspension Fork?
The Lauf Grit SL suspension fork is a very unusual design. It uses glass fiber springs that are mounted to the carbon legs of the fork. The springs react to bumps, allowing up to 30mm (1.2″) of vertical movement, which should make riding on a bumpy road much more tolerable.
According to Lauf, the advantage of this construction (over using a fork with a damper) is the speed at which it can react to a series of small bumps. The Lauf Grit SL should be much more useful on gravel roads where you do not need 100mm of travel, but rather something that can effectively dampen fast, small, repetitive bumps (at least in theory).
However, the advantage is also a disadvantage.
The glass fibre springs themselves cannot absorb much energy, so it has to be released somewhere. This was the main complaint about the Lauf MTB suspension fork; it had an unwanted bounciness that made it simply unrideable for some.
But we are now talking about a gravel version of this fork, and it seems that the bounciness might even be a benefit.
Does It Work?
The Lauf Grit SL works. Just stand on the pedals and you feel the nice vertical movement.
It only has 30mm of travel but subjectively your ride is noticeably more comfortable – that’s both on bumpy forest trails and fast gravel roads.
And to my surprise, I didn’t really feel the bounciness of the fork.
Suspension Stem vs. Suspension Fork
The Redshift ShockStop suspension stem makes your ride more comfortable as it can suspend your upper body from road imperfections. According to my testing, it’s very effective at reducing front cockpit vibrations.
In comparison, the Lauf suspension fork will not only make your ride more comfortable but it will improve the front traction and stability of your bike too. This is because your frame is now suspended at the front (more sprung mass), resulting in the front wheel bouncing less after hitting bigger obstacles.
With a suspension fork, your entire bike becomes much more stable than when just using a suspension stem.
Other Benefits
There is a huge tire clearance on the Lauf Grit SL fork. I mean HUGE!
I managed to put a Schwalbe Thunder Burt 27.5 x 2.25″ tire on the Grit SL with tons of clearance. I believe that Soma Cazadero 700 x 50mm will also fit nicely.
The Lauf fork is also maintenance-free compared to a typical fork, which requires regular servicing. You can just go on your rides, no matter the weather and temperature outside (which can be an issue if you use elastomer solutions).
Keep in mind that Lauf is limiting this fork to riders up to 110kg/243lb.
Changes To The Frame Geometry
The Lauf Grit SL fork measures 409mm in length but it’s 403mm if you take into account 6mm of sag.
If your bike has a 380mm axle-to-crown length, swapping to a Lauf Grit SL fork will slacken your head tube angle by about one degree. This will result in your bike having a slower steering speed (by about 10%).
The good news is that the fork has a 47mm offset. This might help to speed the steering up a bit (by 2-3%) if you’re coming from a 45mm offset.
My Gravel Bike Setup For The Test
I fitted the Lauf Grit SL to my Jamis Renegade benchmark bike for vibration testing. This bike was equipped with supple Soma Cazadero 42mm tires.
I tested the bike with the Lauf Grit SL fork and my Jamis carbon rigid fork. I also tested both scenarios with and without the Redshift ShockStop suspension stem.
I took readings at both 30 psi and 60 psi, the latter was to see what would happen if the tire deformed less.
Vibration Test Results
You can see my vibration measurement procedure & outdoor test courses HERE.
The Lauf Grit SL fork performed better than the rigid fork in all tests on the bumpy forest trail, but it’s perhaps less effective at reducing vibrations than you’d think.
When riding with 30 psi in the tires, the difference between the Lauf fork and the regular carbon fork was only 1.7%. This suggests that most of the vibration damping was being done by the supple Soma Cazadero tire, rather than the fork (the tires at this pressure likely have a lower spring rate).
But bump the pressure to 60 psi and Lauf Grit SL reduces up to 12,3% more vibrations than the rigid fork.
When I added a Redshift ShockStop stem to the system (using both forks), I got a huge 25% vibration reduction compared to without it. This stem is ridiculously effective!
We saw bigger differences on the fast gravel road. The Lauf Grit SL was 9,1% better at damping vibrations compared to the rigid fork (30 psi tire). And with the ShockStop stem installed, the Lauf fork was 9,6% more effective (30 psi).
The Redshift ShockStop stem was again able to provide a huge amount of vibration damping. In this test, 12 to 17% fewer vibrations were reaching the handlebars across all bike setups (30 & 60 psi).
When I increased the tire pressure to 60 psi, the advantage over a rigid fork reduced to just 5,9%. So what happened?
I suspect that because the vibration amplitude is high on the fast gravel road, a lot of energy generated by the Lauf glass fibre springs has to go somewhere. The tire itself likely absorbs this energy when the tire pressure is low but it simply cannot absorb as much energy at 60 psi.
Should You Buy The Lauf Grit SL?
I really like the new feel of my gravel bike. I like it so much that the Lauf Grit SL suspension fork will stay on my benchmark bike for a bit longer. Much longer than I initially anticipated.
But when considering buying the Grit SL, you’ll first want to take into consideration the price (US $990). Based on price alone, I don’t think the Lauf Grit SL should be your first line of defense against vibrations – I’d recommend starting with a wider, more supple tire, and a Redshift ShockStop suspension stem.
If you are still wanting more vibration damping after that, only then should you go for the Lauf Grit suspension fork. When combined with my supple tire and suspension stem, it’s one of the most effective ways of achieving a comfortable gravel cockpit.
Of course, you’ll also appreciate the extra traction, braking, and ride stability on rougher terrain that a suspension fork can offer.
A Small Update
After a few more weeks of testing, I found two more things that should be mentioned:
– The fork whistles! If the wind is strong, the fork makes some noise.
– And riding on the tops is the least beneficial in terms of comfort. The more weight you put on the hoods, the more the Lauf fork can work for you.
