Reuleaux polygon bicycle - uses triangular/pentagonal wheels

mrgarci1

mrgarci1

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http://technology.timesonline.co.uk/tol/news/tech_and_web/article6366308.ece

Evidently you can construct these shapes that are not circles, but have diameters that are the same, no matter how you measure them. I don't completely understand the underlying math, but it's pretty cool that a bike with such weird wheels can be pedaled without the saddle bobbing up and down (which it doesn't).

My favorite bit from the article comes right at the end:

Conundrum
If you make a drill piece in the shape of a Reuleaux triangle, what shape hole will it drill?

Answer
A Square. Well, almost. The corners of the square are slightly rounded. :shock:
 
What isn't apparent here is that the axle(s) would create a "bobbing up and down" of the bike's saddle, unless the position of the axle is constantly adjusted with respect to the bike's frame.

Which is, engineering-wise, an expensive and commercially prohibitive exercise. Round wheels are better from all considerations. This bike is just a gimmick.

Cheers :)
 
The only reason the seat's not bobbing is because it's resting on top of the wheels. The wheel diameter doesn't change, but the hubs are bobbing up and down like crazy. :p

Gimmick indeed. :D

PS... I don't see how any fixed position drill bit is gonna make anything but an elliptical hole...
 
mrgarci1 said:
My favorite bit from the article comes right at the end:

Conundrum
If you make a drill piece in the shape of a Reuleaux triangle, what shape hole will it drill?

Answer
A Square. Well, almost. The corners of the square are slightly rounded. :shock:
Click to expand...
If it's a drill piece, it will make a round hole, all things do that spin on an even axis. The axis itself would have to be moving around in sync with the drill rotation to make a rounded square hole.

Wood workers know all about this, but they would never claim that just something spinning will make square or triangular holes while stationary, LOL.

I'd like to see the bike in action, my bets are that is does bob up and down.
 
It'll make an elliptical hole if it's drilling into a plane at an angle -- a circle is also an ellipse. But square-ish? No.

I didn't see it either at first, but the frame of the bike is actually resting on top of the wheels, not on the hubs. At first I thought the forward motion of the thing would feel a little hurky-jerky while he's pedaling it even if it didn't bob up and down, but then I realized since the mass of the rider and frame are not rising and falling, the forward motion should also feel pretty smooth.

It will introduce reliability problems with no benefits I can see, other than being eye-catching. But gimmicks have their uses -- I wonder how much he got paid to put the Beijing Olympics logo on it. 8)
 
Wierd as a Safe thread. :roll:
 
Hey I'm not saying it's not a gimmick, or that it even has ANY practical use - I just found it very interesting that such a machine could be constructed. Although I'm still thinking about what else could be done with this idea...
 
I imagine it's not a very comfortable ride, for one thing -- looks like there is absolutely no cushioning. Would be fun to ride around though, definitely a conversation starter.
 
IMy guess on the square hole thing is that they are referring to a hand-held drill rather than a fixed one, which would vibrate madly around the hole and the resonance would form a squareish shape. Think of a rotor in a rotary engine.
 
What the heck do they use for TIRES??
 
velowatt said:
What the heck do they use for TIRES??
Click to expand...

Something very slippery, as it has to slide along the frame on the top edge. Hence the comment about being harder to pedal than a normal bike.

Not recommended for going downhill. Or riding in traffic. Or looking cool. Or getting from A to B in an efficient manner. What was this bike for again...?
 
Grinhill said:
velowatt said:
What the heck do they use for TIRES??
Click to expand...

Something very slippery, as it has to slide along the frame on the top edge. Hence the comment about being harder to pedal than a normal bike.
Click to expand...

He's probably got bearings rolling on the top of the wheels... but it really doesn't look like there's any cushioning, including tires. I think he's just got a layer of rubber, and that's it. Ow.
 
You're correct- I found some other photos of this, and there's rollers on the part of the frame that contacts the wheels, so you could use "sticky" tires instead of slippery ones.
 
If you see a guy with a ponytail on a bike with triangular wheels in, say, another six months or so, it's probably me. :?
 
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