Bicycles

Funny-looking fork won't take a dive

Funny-looking fork won't take ...
The Motion France fork certainly has a look of its own
The Motion France fork certainly has a look of its own
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The Motion Fork's leaf springs are available in different stiffnesses, and can be swapped in and out depending on rider weight and the amount of travel desired
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The Motion Fork's leaf springs are available in different stiffnesses, and can be swapped in and out depending on rider weight and the amount of travel desired
The Motion France fork certainly has a look of its own
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The Motion France fork certainly has a look of its own

As long as there have been mountain bikes, there have been people experimenting with linkage-style suspension forks. Unlike traditional telescoping forks, they have a hinged design which allows them to absorb impacts by "folding" up and down. France's Motion Engineering is now taking a modern crack at the technology, with its brake-dive-eliminating Motion France Dynamic fork.

Unlike some earlier efforts in the field, the Motion fork doesn't incorporate an elastomer, air or coil-spring shock absorber. Instead, it has a set of carbon composite leaf springs (green-edged things in photo below) extending from the linkage down the backs of the fork legs. These springs are available in different stiffnesses, and can be swapped in and out depending on rider weight and the amount of travel desired.

An adjustable oil damper in the head tube takes care of rebound, and allows users to lock out the fork when suspension isn't needed.

The Motion Fork's leaf springs are available in different stiffnesses, and can be swapped in and out depending on rider weight and the amount of travel desired
The Motion Fork's leaf springs are available in different stiffnesses, and can be swapped in and out depending on rider weight and the amount of travel desired

The design is claimed to be maintenance-free, more sensitive than a regular telescoping fork, and – as mentioned – immune to brake dive. In other words, when the front brake is applied while at speed, the fork won't compress. This helps keep the rider's center of weight from being pitched forward, and also allows the fork to retain its full length of travel when stopping.

Motion Engineering has previously displayed prototypes at trade shows, and has now turned to Kickstarter to finance production of the new Trail version of its Motion fork. The Trail is in turn being offered in two setups – one made to fit 29-inch/27.5+ wheels, and the other for straight-up 27.5-inchers. The two setups offer 110-150 and 120-160 mm of travel respectively, and tip the scales at a claimed 1,850 grams (4 lb).

If you're interested in getting one, you can do so for a pledge of €1,250 (about US$1,381), which is 50 percent the planned retail price. Assuming it reaches production, delivery is estimated for next July.

You can see a group of test riders trying out the fork, in the following video.

Sources: Motion France, Kickstarter

MOTION FRANCE Precursor's day - Sept 24th, 2016

8 comments
over_there
wont the anti dive characteristic also cause less grip under braking when you need it the most
JasonCornish
it should not cause less grip and since typically front wheel grip during breaking is not an issue for a rigid forked mtn bike even some loss of suspension activity under breaking would not cause major problems in that area. I remember the old pro-flex forks; they were fragile. Hopefully this one is stronger but in the end it will revolutionize nothing. It's just a toy for people wanting to look different.
Bob Stuart
How does it work? Is the spring connected to the reaction arm of the brakes? How well does it work?
Matt Letch
USE did one years ago - single sided as well
https://www.google.co.uk/search?q=USE+sub+fork&espv=2&biw=1144&bih=676&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjm2pnHstXPAhWpJcAKHcxlDLwQsAQIKA&dpr=1
Stradric
I think this is a neat gadget academically, but it seems like a really pricey solution for something that simply shifting body weight back would solve. Maybe I'm underestimating the problem.
habakak
At $2762 that's outrageous for a suspension fork. Also, they need to accommodate 29+ if they want to stay current. The Lauf fork works similarly but not quiet as complex. The bushings on the links of this fork would most likely need to be replaced every year (like with rear suspensions) otherwise you risk permanent damage. So, it takes away some maintenance but adds it in other places. The Lauf I think is overall a much simpler (and lighter weight) solution that is available now and cheaper than even the Kickstarter campaign price.
Timelord
@over_there: No, it won't do anything to the traction. @Bob Stuart: It's hard to tell because they don't give any explanation or clear photos, but it looks like all the links at the top of the fork form a parallelogram when seen from the side. During normal suspension action, the parallelogram tries to squash shorter vertically. During braking, the bottom of the fork experiences backward forces, which uses the fork legs as levers. The forces go through all the pivots to try to straighten out the parallelogram into a taller, closer-to-rectangular shape. That force counters the load transfer to the front wheel that causes brake dive. Aside from the price, the complication gives me the willies. As habakak wrote, the bushings will need periodic maintenance and replacement, and there are a lot of bushings in this design.
MotionFrance
Thanks to all of you for your comments. Critics are useful to us in order to know what we must explain better about our fork. We'll do so on Kickstarter but as I'm here with you, I will give you further explanations right now. First of all, we agree that what you can see on the pictures is the last prototype currently used by more than 30 MTB pilots. Presales on Kickstarter concern the TRAIL series that you can see on Kickstarter or on www.motion-france.com . @over_there If you brake and don't dive, you keep 100% of your travel available. So, your grip is much better and you have a better control. @JasonCornish Perhaps you're right about old pro-flex-forks when you write they were fragile. I don't know. But anyway, it is not because you can see 4 axes that you can compare. It was not anti dive and not sensible at all as it was using a damper. Perhaps you can compare the pro-flex with the German A fork but not with Motion France fork. The aim and characteristics are quite different. So yes, it is revolutionize everything and this is why there is a patent on the anti dive and another on the pulled composite blades. Same answer @Matt Letch about USE fork. @Stradric When you shift your body weight back, it doesn't solve the problem of diving while you breake and loss of travel and control. This is why even motorcyle companies such as BMW work on a way to avoid diving under breaking. Furthermore, when you go downhill and you dive under breaking, you increase the degree of the downhill and the risk of an OTB (Over the Bike). With the anti dive system it is safer and you can brake harder. @habakak I am pleased to advise you that we accomodate 29''+. There is no other fork offering anti-dive and sensitivity like Motion France Fork. If $2762 is outrageous, you should take advantage of the current campaign on Kickstarter where you can save 50%. Regarding your comparison with the Lauff, I invite you to double check caracteristics of both forks. If you still can't see the differences, feel free to ask me. Goal, use and characteristics are very different. @Timelord I would say that you have understood most of what happens when you brake with a Motion fork. But don't have "willies". There is much less complication than in a telescopic fork and that one is life guaranteed. If you need further information, don't hesitate to send a message via our project on Kickstarter.