Lauf fork turns over a new leaf in mountain bike suspension
Telescopic suspension forks may have done a lot to make mountain biking easier and more enjoyable, but they’re not exactly light or mechanically simple ... at least, not when compared to rigid forks. Icelandic entrepreneurs Benedikt Skulason and Gudberg Bjornsson decided to do something about it, and together created the Lauf leaf-style fork. It has no moving parts, requires no maintenance, and weighs just 980 grams – a typical suspension fork weighs more in the neighborhood of 1,400 to 1,900.
Here’s how it works ... the main fork legs are made out of carbon fiber, and look pretty normal (apart from the backwards jog they take at the bottom). The wheel axle is mounted through a couple of other carbon fiber bits known as springers, one on each side, located behind those legs. Diagonally bridging the gaps between the fork legs and the springers are four “springstacks” – two on each leg. Each one of those springstacks in turn consists of three stiff-but-flexible ribbon-like leafs, made from what is described as “high-performance composites.”
It is those springstacks that absorb the bumps, allowing the front wheel to move up and down independent of the fork legs.
The current version of the Lauf fork features just 60 mm of travel, so it may not be enough for non-cross-country riders – conventional trail-riding forks typically start around at least 110 mm. It also can’t be adjusted for the weight or riding style of individual riders. Instead, buyers choose from three different models, each one pre-tuned to a different stiffness.
Finally, riders of bikes with 26-inch or 650B wheels are out of luck – the Lauf is made only for 29ers. In fact, at this point, it isn’t even available to consumers or retailers. Skulason and Bjornsson do hope to have it available as an option on certain makes and models of bikes by next year, however.
It can be seen getting put through its paces in the video below.
Source: Lauf via BikeRadar
About the Author
An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.
All articles by Ben Coxworth
Cool. regular shocks absorb - these look like they store and return, so probably do not rob energy from the rider?
You guys should find a short rocky downhill slope, free-wheel down it, and see how much further these things roll out at the end, than a regular shock.
"It has no moving parts". Explains why it doesn't work all that well. Still, the parallelogram method of keeping the wheel in alignment is a good start.
It has no moving parts but has 60mm of travel. Correct me if I'm wrong but you've got to have moving parts to get any kind of travel.
The only way I can see fork being marketed with no moving parts is if the springers and springstacks are sold as a separate unit as part of the hub on the wheel.
"Correct me if I'm wrong but you've got to have moving parts to get any kind of travel."
Nope - material flex isn't a "moving part".
The idea of flex as suspension isn't new - "softail" mountain bikes have relied on inherent flex in the frame for years, admittedly usually in "pivotless" designs, with the actual shock-absorption being provided by a small shock or elastomer, and flex in the (often flattened) chainstays replacing bearing pivots.
Cannondale's Speed Save technology relies entirely on flex, however.
Having some small experience of carbon fibre as a material, I'd prefer Lauf to use titanium plates rather than carbon fibre - titanium doesn't fail catastophically the way carbon fibre is wont to do...
Motorcycles had similar arrangements,I say similar as I'm unsure about the parallelogram set up, but leading link and trailing link forks were very common in the 50s and 60s and even the humble Honda 50 step through had a similar suspension.
Rubber bushes held in torsion were often the "spring" of choice in the past .
To really save weight, spring-pivots can be used in many designs right in the primary load path, instead of making a detour. The Hossack system of suspending the steering head might save even more weight.
With this much travel, dampers become more necessary. They are harder to integrate. They also rob power, though not as much as bouncing with no springs. A rising-rate spring needs less damping, and a friction "shock" with a soft mounting ignores the little stuff.
To avoid pogo-ing, a spring fork should be matched to a rear suspension with extreme anti-squat geometry, so the bike only rises and falls with no pitch from pedal reactions.
@Martin H. : "moving parts" is usually taken to mean "with pivots." Everything moves as a spring, on close examination.
In this design I see the springs. But no dampers.
The damper is the "absorber" part of the "shock absorber". You really need that part. Spring only = bouncy bouncy crash bang ouchee.
As others have stated... No damping! If you want an innovative spring design then this is for you. If you need rebound and compression damping... well then you'll need a few moving parts.
I've always preferred linkage forks. I have a Lawwill, a Girvin and an AMP (all of the last of the series). They are inherently limited in the amount of travel but are much more stable against side deflection (imho). All of the aforementioned have dampers.
So "moving parts" is usually taken to mean "with pivots". So a regular shock would not be a moving part? A ball bearing used as a check valve would not be a moving part? A cut off sled on a table saw would not be a moving part? Perhaps no surface to surface motion would be a little better.
I would guess that the reason it is limited to 60mm travel is that the springstacks would have to be longer to alow more travel. This would result in even more drastic changes in the geometry and handling as the wheel moved in and out from the rider, vs primarily up and down with a suspension fork.
"If the fork, with springers and springstacks, is sold as a complete unit and is therefore in its entirety the "fork" then it does in fact have moving parts"
That's like saying a fishing rod (minus reel) has moving parts because it bends...
If the fork, with springers and springstacks, is sold as a complete unit and is therefore in its entirety the "fork" then it does in fact have moving parts. The springers and the springstacks move independently of the main structure of the fork and it does not matter how that movement is allowed.
Also, the springstacks are nothing more than leaf springs arranged in a cantilever setup.
If flex, by your definition, is not movement then the same would apply to automobiles that use a leaf spring suspension. This will be a boon to the automobile industry because it means that, since nothing under the springs is moving, there is not one ounce of unsprung weight on a vehicle that uses a leaf spring suspension system.
Torsional rigidity numbers?
What a useless video. The camera deflection at the point of impact with the ground contact completely blurs the images. What they should have done was jump the bike 5 or 6 times right next to a ground mounted camera so they could get perfect video at least once. Useless as is.
I agree with Don--A better video would help Lauf demo the fork. The still cam idea might be better. This one is useless.
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