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Bicycles

Loopwheels put a spring in your cycling

By Ben Coxworth
April 17, 2013
Loopwheels put a spring in your cycling
A set of Loopwheels, on a Dahon folding bike
A set of Loopwheels, on a Dahon folding bike
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A set of Loopwheels, on a Dahon folding bike
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A set of Loopwheels, on a Dahon folding bike
The Loopwheel attached to a testing rig
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The Loopwheel attached to a testing rig
Instead of relying on a suspension fork and rear shock, the Loopwheel lets the bike’s 20-inch wheels absorb the bumps
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Instead of relying on a suspension fork and rear shock, the Loopwheel lets the bike’s 20-inch wheels absorb the bumps
A test loopwheel under compression
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A test loopwheel under compression
This illustration shows how the Loopwheel handles bumps compared to a conventional spoked wheel
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This illustration shows how the Loopwheel handles bumps compared to a conventional spoked wheel
The Loopwheel reacts to a force from any direction
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The Loopwheel reacts to a force from any direction
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When you have plenty of bicycle to work with, such as is the case with a mountain bike, it’s not such a big deal to design it with front and rear suspension. When the bicycle in question is a diminutive folding city bike, however, it gets a bit trickier. That’s why UK industrial designer Sam Pearce has created Loopwheels. Instead of relying on a suspension fork and rear shock, it lets the bike’s 20-inch wheels absorb the bumps.

Each wheel incorporates a regular hub, with a hub brake and hub gearing. Instead of spokes, however, three looped carbon composite springs run from the hub to the rim. Whenever the wheel hits a bump in the road, the energy is absorbed by those springs.

This causes the hub to momentarily dip down within the wheel by up to 45 millimeters, so it’s actually a bit off-center until the springs flex back into their regular state. For this reason, the wheels will only work on bikes that already have sufficient space between the fork/frame and the tire – otherwise the bike would be hitting its own tires when the springs compressed.

Loopwheels come in front- and rear-specific versions, one of the key differences being that the springs in the front wheel are twice as compliant as those in the back. This is (presumably) to help keep the wheel that does the steering from being knocked and bounced around, plus it compensates for the fact that more of the rider’s weight tends to be centered over the rear wheel.

Each wheel reportedly weighs about 300 grams (10.5 oz) more than a comparable spoked wheel.

Instead of relying on a suspension fork and rear shock, the Loopwheel lets the bike’s 20-inch wheels absorb the bumps
Instead of relying on a suspension fork and rear shock, the Loopwheel lets the bike’s 20-inch wheels absorb the bumps

According to Pearce, one of the advantages of Loopwheels is the fact that unlike a suspension fork, they can absorb shocks delivered not just from underneath or above but also from the front (as might happen when running into a curb head-on). He also admits that many other inventors have come up with designs for wheels with tangential suspension over the past hundred years or so, although he believes that today’s modern materials will allow his to work where others have proved impractical.

Pearce is now raising production funds for his Loopwheels, on Kickstarter. A pledge of £195 (US$297) will get you a front wheel (which can be used with a conventional rear wheel), while £420 ($640) will get you a front and rear set – when and if the funding goal is met. A 26-inch model for mountain bikes is also in the works.

The wheels can be seen in use in the pitch video below.

Source: Kickstarter

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9 comments
Ben Coxworth
Ben Coxworth
Based out of Edmonton, Canada, Ben Coxworth has been writing for New Atlas since 2009 and is presently Managing Editor for North America. An experienced freelance writer, he previously obtained an English BA from the University of Saskatchewan, then spent over 20 years working in various markets as a television reporter, producer and news videographer. Ben is particularly interested in scientific innovation, human-powered transportation, and the marine environment.

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9 comments
Slowburn
I played with the idea using steel springs in wagon wheels for a Ring of Fire series fanfic (I highly recommend the books if you like time travel stories) but I am not convinced that loopwheels are a better solution than a springy seat post.
Michael Lau
would there be negative effect on the bikes performance?
Frank van Schie
@Michael Lau Presumably yes, since part of your energy will go into moving the hub within the wheels. But since they're springs, you'll get most of that back, so it's probably close enough to a wash to not matter much. Especially on a purely A-to-B type bike like a folder.
Although a good folder can get some awesome performance.
I like this idea! Would like to see a review by someone impartial.
Edison Ong
My background in wheel performance is its circular motion( which involves the circular of the wheel, and that the hub remains in the center of the wheel) if u are rolling with an oblong wheel, then u may actually exert more effort in lifting your self with the bike rather than rolling.
For me, base on this design, as long as you can maintain the hub to be: ground to hub distance would always be greater than the hub to the horizontal distance (radius) to the rim. then you should be fine.
Cases to consider: 1: Idle - the spring should be able to carry the rider with no deflection, other wise if u lowered the spring from the beginning making the ground to hub distance smaller than the horizontal radius, you might experience lifting. but if it can support i believe its good
2: forward- in a plane terrain riding, if your moving forward. (with the 1st case scenario considered) i think its good to.
2.1: Humps - if u roll over a hump, den the shock can make the hub offset.but if it maintain with the situation i wrote on top. then you'll have the case o rolling in a "something like a smaller wheel since the radius reduced" but will be fine, then after the humps, the wheels would recover the shape. here you'll still good
3: Down hill- I think this would be the least of your problems. not to mention if you're fine with the previous scenarios. " a box can slide with free fall"
4: Up hill- this is where i think you may encounter difficulty. since its a climb. assume that you follow case 1, then you should be at least fine here. you have to focus on the ground distance to hub must always be greater than radius of wheel parallel to inclination of climb. (because imagine case 1, if your hub is no longer at the center, you will be lifting your self. in an inclined position. more difficult than lifting in a plane.
I still like this invention and consider it an innovation.
(My comments are "my opinion" only, please do not take it negatively. I did not see this in person, so I COULD BE WRONG. Comments are base on my mechanical behavior experience)
Go Innovators! =D
francm
How does it constrain the axial translation and the 3 rotations? Is is springy in all those 4 directions as well?
Greg Mixson
Near the end of the video it shows the bike on the "rolling road" test bed, the rim is moving laterally, not good in most bike applications.
wle
ew springs without shocks, what good is that? and shocks, they slow you down a lot when you dont; need them ew again just something else to cost more, add weight and subtract speed no thanks plus when you stop the bike will dive
wle
Michael Crumpton
The big limitation that I can see, is that if there is any deflection when the rider gets on the bike, that means that the rider is essentially pedaling uphill all the time (Because he has to compress the springs as he moves forward).
The other problem is that unless the springs are precisely calibrated to the riders weight this will really destroy the rolling efficiency of the bicycle.
Malcolm Jacks
I bought a pair of loop wheels a couple a years ago, unless they have improved, i found they bend from side to side. After spending a lot of money on them, i returned to my spocked wheels. So far there is nothing to beat the spocked tried and most successful design. the best suspension i found is seat post suspension and front faulk suspension.