christ0ph

While looking at the Wikipedia web page on "emergent technologies" I stumbled across a word that I had never seen before "tweel"

"The Tweel (a portmanteau of tire and wheel) is an experimental tire design developed by the French tire company Michelin. The tire uses no air, and therefore cannot burst or become flat. Instead, the Tweel's hub connects to flexible polyurethane spokes which are used to support an outer rim and assume the shock-absorbing role of a traditional tire's pneumatic properties."

"The Tweel consists of a cable-reinforced band of conventional tire rubber with molded tread, a shear band just below the tread that creates a compliant contact patch, and a series of energy-absorbing polyurethane spokes. The rectangular spokes can be designed to have a range of stiffnesses, so engineers can control how the Tweel handles loads. The inner hub contains a matrix of deformable plastic structures that flex under load and return to their original shape. By varying the thickness and size of the spokes, Michelin can generate a wide array of ride and handling qualities. The tread can be as specialised as any of today's tires and is replaceable when worn.[1]
"

The Wikipedia page also states this, which I thought might also apply to malicious anti-bicyling puncture strips which people in Portland have recently been finding on bike trails..: "The Tweel can also withstand a police 'stinger' spike strip, which would force law enforcement to adapt in order to catch a suspect in a vehicle equipped with Tweels."


According to a 2006 article on BicycleTech blog https://bicycletech.blogspot.com/2006...of-future.html

which quotes gizmag.com.au (more here) "The Tweel promises performance levels beyond those possible with conventional pneumatic technology. The first commercial applications of the Tweel will be in lower-speed, lower-weight vehicles"

Looks as if it would work on bikes, definitely. I'm sure somebody, somewhere has tried it..

They look promising. A flatless, shock absorbing, fast wheel.

Looigi

I like the idea of thinking outside the box and thinking different, but this sounds really heavy and high rolling resistance...maybe acceptable for utility or delivery bikes (not messenger bikes).

CaptCarrot

Doesn't sound that it will ever be used outside the utility/comfort market to me. But inside that market it could do quite well.

prathmann

Agreed. The pneumatic wheel is remarkably efficient since almost all the energy used to compress the tire at the front of the contact patch is returned by the re-expansion at the back of the patch. This is especially true of lightweight road bike tires with minimal tread and either tubeless or thin latex tubes. I doubt that the plastic matrix in the Tweel will be anywhere near as efficient in returning the energy needed to compress it as it rolls along the road.

pg13

hmm. was going to say something else then read captcarrots post and makes me doubt theyll even do well there. and looking at the pics i dont think theyve got any could put on a bike and im not sure if that would be suitable for a bike. i mean besides the size where you gonna put brakes on that? https://www.gizmag.com/go/3603/picture/26521/ i could see it for bikes that are designed to go into very bad terrain and need to be able to get over pretty much anything and atvs too.

edit: just noticed it was updated april 29th 2005

mechBgon

Given the high height-to-width ratio of a bicycle wheel, that doesn't look too promising for conventional bicycle applications.

CaptCarrot

Discs?

Well spotted.

christ0ph

Disc brakes.. And the web pages I saw sounded as if it can achieve 95% efficiency which is not as good as the best bicycle tire but its far better than the other airless tires out there now..Also they dont have to be wide, they can be as narrow as a bike tire bit also flatter on the bottom which means more traction. The spokes are slightly elastic, though, so torque (thust, braking) would be very slightly delayed as a function of the elasticity. But not much, because they would be very tightly tensioned..just enough give to give it a bit more give. I could also see the increased contact area as offering some ability to stop and start faster..I think its just a slightly different beast, its not at all clear to me that its inferior - for example, it says there that NASA is using "tweels" on the next gen lunar rover..

christ0ph

Ah.. I should have included this URL at he beginning but I have so many windows open I lost it.. this is a *bicycle specific* article Although, yes, it is old.. 2006. Wikipedia was the first I had read about them though..


https://bicycletech.blogspot.com/2006...of-future.html

pg13

yes but captcarrot i dont see how they can put discs there. second if the wheel is all deformable how is that going to react to a brake like a disc? the middle would stop the outer it seems would go on and stretch and collapse? in that link from the hub to the tire is all deformable. and yes i didnt bother to check the date because he said it was emergent but i should have noticed sooner

clydeosaur

They tried this on cars years ago. Verdict? no better, infact inferior. No clear advantages outside of flats. Price was not mentioned much, so I doubt there was much advantage there too.

christ0ph

The tire in its current incarnation is a overwhelming positive for bicycles, and in a sense is an extension of the human body. The only major problem is flats, but that is a big problem in traffic on a bike, because there's no redundancy.

pg13

What flats? The tires dont have any air in it which is one of the supposedly major selling points for these wheels.

CaptCarrot

I 'spose the same argument could be put forward for rm brakes - even though the stresses are less, they are still there.

pg13

I could see it not being to big a problem in the rear though still annoying. But the front? Wouldnt that possibly raise the otb chances if you had to stop suddenly and suddenly the front wheel collapses a few inches? All well. This is all just speculation though Ill admit the idea and creativity is nice, just I dont think for bikes or anything umm somewhat speedy? is fit for.