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Sam Pearce's Loopwheel: Tangential Suspension for Bikes

By Rain Noe - April 24, 2013

in Kickstarter

Six years ago, industrial designer Sam Pearce was sitting in an airport when "I saw a mother pushing her child in a buggy," he writes. "The front wheel hit a slight kerb [sic] and the child jolted forward because of the impact. It happened several times in the time I was waiting there." He then did what many ID'ers do, which is to find the nearest piece of paper and sketch out a potential solution. What he drew in his notebook was this:

A simple idea for a wheel with built-in suspension.

Two years later, while off-road cycling, he remembered the sketch and began thinking if a suspension system like that could be built into a bike wheel. Now, many years of tinkering later, what Pearce has come up with is this:

It's called the Loopwheel, and its system of "tangential suspension"—essentially leaf springs folded back in on themselves—are not only workable, but they provide a gentler ride over sharp obstacles due to physics:

For now, Pearce is focusing on developing Loopwheels for smaller bikes, because the design "[allows] suspension where suspension can't normally fit," as with a folding bike design.

Last month Pearce debuted his creation at the UK's Bespoked Bicycle show. Response was tremendous, and he's now seeking Kickstarter funding to get the Loopwheel into proper production; up until now he's been making them as one-offs in his shop.One of the cool things about Pearce's Kickstarter video is that he not only shows you the Loopwheel, but also shows the simple machines he's rigged up to test them out:

And here's the vid:

Pearce has nearly reached his funding goal—at press time he was just £4,000 shy of the £40,000 target—but interested pledgers still have until May 15th to buy in.

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Horst

11 years ago

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Quod erat demonstrandum

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Robyn

11 years ago

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I made that exact same sketch a few years ago too.
Well done on following it up rather than sitting on it like i did.
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Mike Doell

11 years ago

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There was a moon rover concept from Grumman back in 1963 with wheels like this.
Grumman LSS Project 344 Rover
http://www.astronautix.com/craft/grur1man.htm

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Pericles Leite

11 years ago

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No, the chains would not suffer (what was I thinking...).
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Pericles Leite

11 years ago

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There may be some damping due to hysteresis...

The springs will "absorb" part of the traction and braking energy, which may happen with conventional suspensions too, but in this case the "cause and effect" will be much more direct.

And as the hub moves in comparison to the rim/tire (contact patch), it may have "constant changing" final gear ratios. The chain may suffer a bit too.

The problem with brake disks (one disk per wheel) with this wheel, is that the braking force will be applied offset to the hub/wheel symmetry plane, so when breaking, the bike will push to one side, which again, happens with other bicycles and motorcycles too, but this will be much more pronounced with this wheel, I think.

But it is impressive nonetheless.
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mackey

11 years ago

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Interesting idea, but it still amazes me that people always look to 'improve' the bike by modifying it's most highly evolved and mature parts.

Relatively few attempts to improve cycling through the relatively low-hanging fruit of new forms of infrastructure...
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Andrew

11 years ago

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I can't imagine they're fun to clean either. Lots of little gaps. That said, cool concept for small/ folding bikes though where lateral stiffness wouldn't really play a huge role and where comfort would be a prime feature.
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Ken J

11 years ago

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I have no concerns with the concept, just curiosities. I see a need for the spring mechanisms to span the full diameter of the wheel. He seems to have provided plenty of travel in his smaller wheel design to accommodate larger wheels. How about not scaling up the size of the spring to the wheel but instead finding an ideal size. Focus tooling and manufacturing on that size, and if larger wheels are needed, just spoke out to the larger dimensions. If that still doesn't work, perhaps some interlacing plates (composite?), say two on the hub, and one on the rim, that allow the hub to move radially, but restrict it axially.
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Ben

11 years ago

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Having been at Bespoked and spoken to Sam, and had a small ride on the bike pictured above, I got the impression that Sam has thought through all of your concerns.

The most unexpected bonus of the design is that when you hit a bump, the system actually propels you forward once you are over it.

In terms of clearance, the amount of travel in the wheel is very small, but enough to make things a bit more comfortable. Lateral stiffness is also within wheel manufacturing limits (about 3mm each way off the top of my head).

I asked Sam about bigger wheels, and it's something he's working on. The problem is that lateral movement is exaggerated on larger wheels, so the design needs a bit more work.

As a cyclist and cycle mechanic, I can also say that rim brakes are the past and disk brakes are the future :P

I can't wait to buy a town bike with them on!
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J.Eriksson

11 years ago

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The graph for the Conventional Front Suspension is wrong. It only looks like that if there is no suspension or really hard suspension, in low speeds. With conventional suspension you can tune it by softer/harder springs and smaller/larger dampening to get the graph exactly like the Loopwheel as per classical mechanics.
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Douglas Schaller

11 years ago

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Amazing concept! The linear stability seams to scare me a bit. I wouldn't want to take a sharp turn with those wheels. They don't seem like they would every stay true. Even the video shows them wobble. Still ,very impressive.
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James Patrick

11 years ago

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I wonder how well they handle lateral pressure. Aren't these essentially Tweels?
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goodmaei

11 years ago

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So many issues, so few answers...rim brakes won't work -- disc brakes or drums (like in the video) would be needed, which keeps them off a lot of existing bikes. Fork and frame clearance may be a problem, particularly for bikes with standard size wheels. Also, the wheel forms a simple spring, without additional damping, which will make for a bouncy ride. Nice look to it, though.
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Ken J

11 years ago

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No mention of the way the wheel feels to pedal. I'd imagine the wheel would resist turning as the spring absorbs the riders energy. I'm curious as to how the bike would feel returning that energy as it is not dampened, but instead sprung.
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