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Super-light pursuit, anyone?

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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

Super-light pursuit, anyone?

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Old 08-30-05 | 02:40 PM
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Super-light pursuit, anyone?

Yet another concept bike. I actually find this one kind of attractive, and it's actually feasible.

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Old 08-30-05 | 02:45 PM
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Wait. No it's not. At first I was thinking that you could use an internal gearbox to increase the gearing but at the end of the day you're still translating motion from the diameter of the directly driven gear attached to the cranks to the diameter of the wheel, a huge stepdown.

Rats.
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Old 08-30-05 | 02:48 PM
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Im curious to know how they plan to strengthen the rims so that theyre rigid without feeling really heavy. How is that front wheel mounted again? Magnets?
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Old 08-30-05 | 03:04 PM
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Carbon fiber...or magic!

Anyhow, the rim is actually a very large roller bearing with the tire attached to the outside. The steering column would be attached to the interior, stationary part of the rim.

Actual moving vehicles have been built with this technique and it is sound. Here's one now:



This page features one that might actually be rideable.
https://www.osmoswheel.com/pages/application_cycles.asp

The seatpost could be attached to the fixed portion of the wheel which would be in turn attached to the frame. You could then attach a drivetrain to the rear wheel which actually has a hub.

The handlebar and steering column would be attached to the interior of the hub and the brake would come into contact with the braking surface on the moving portion of the rim. At the bottom of wheel it would attach to the front of the frame with a pivot that would allow you to turn the wheel...at least to the left.

Of course you could combine the two ideas, borrowing the rear wheel and drivetrain from one and the more sensible steering from the other
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Old 08-30-05 | 03:24 PM
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well I was stoked at your first post, but after reading your second post I believe I'm just going to be sick!

still, a nifty gadget.
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Old 08-30-05 | 03:51 PM
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The gearing on that bike could work, but it requires at least three gears inside that housing... probably more than that.
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Old 08-30-05 | 03:56 PM
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The cranks actually turn a generator that drives a small electrical motor!
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Old 08-30-05 | 04:39 PM
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If the entire wheel is a huge roller bearing, are there a lot of bearings in there adding to the friction? Possibly more friction than a typical wheel. A very cool picture anyway, it makes you think.

Do they claim that is a picture of a real bike? (the pursuit)

I wonder what it is like to change a front tire flat on that chopper ?


I think this monowheel is interesting. I just have one question. What happens if you put the tire up against a solid brick wall and open the throttle ?

Last edited by 2manybikes; 08-30-05 at 04:55 PM.
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Old 08-30-05 | 05:08 PM
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Originally Posted by Mouton
The cranks actually turn a generator that drives a small electrical motor!
I'd thought of that. There is no possible mechanical linkage which could provide a useful gear.
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Old 08-30-05 | 05:11 PM
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Anyone remember the Spiral Zone cartoon? I loved that show. The rimfire was like the above, only with a huge cannon on top. All I could find on the Googles was this crappy picture of a crappy toy:

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Old 08-30-05 | 06:32 PM
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Wait.

If a planetary gear can give you a better than 1:1 ratio, couldn't such a thing be done with this as well? The wheel rim is just like a really huge annular ring.

I'm confused.
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Old 08-30-05 | 11:51 PM
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for some reason i think it's possible, i just have to figure out the math behind it...
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Old 08-31-05 | 12:02 AM
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You could make it work the same way you make a double reduction gear work. You jsut have to package the whole thing inside that little housing around the cranks, which means you'd probably nead really narrow parts, especially since it looks like you might need a triple-reduction setup for a bike like that.

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Old 08-31-05 | 12:16 AM
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I'm surprised you fixed people actually even consider things like this, with your love of simplistic machines and all. Put an internal gearset or planetary gears on that thing and I'd be forced to ride up as cross-chained as possible and remark on your drive inefficiency.
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Old 08-31-05 | 01:43 AM
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Yeah, a setup like that would need a good couple of cog interfaces, double or triple reduction, which would prolly have loads of friction.
The wheels would likely also be heavy and have lots of drag themselves.
But: if they could build the thing properly, it would be aerodynamically wonderful. Wheels have no spokes, there are no large vertical surfaces like headtube, seatstay and seatpost...

But that's a computer-drawn sketch only, and I'm afraid that all the funny parts (drivetrain) would have to be a lot larger to work, and wouldn't work effectively.

Axle-less wheels have been made to work already, though, on trucks, buses motorbikes, etc, so maybe it'd be possible to build a good front wheel like that. Has killer aerodynamic potential: No fork, no spokes, and of course the front wheel is the first thing to slice through the air, much omre important than the rear which is pretty much out of the air stream anyway.
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Old 08-31-05 | 02:02 AM
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Originally Posted by bostontrevor
Anyone remember the Spiral Zone cartoon? I loved that show. The rimfire was like the above, only with a huge cannon on top. All I could find on the Googles was this crappy picture of a crappy toy
hell yeah, someone else actually remembers that show, i was really into it


i saw a crazy concept looking bike on FGG a while back...dont remember what it was called though, anyone know? it was a museum piece or something...


something along the lines of this bike could be cool too...i imagine most people saw this in that bike hoax thing that floated around the internet a while back?
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Old 08-31-05 | 07:41 AM
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Originally Posted by bostontrevor
Wait.

If a planetary gear can give you a better than 1:1 ratio, couldn't such a thing be done with this as well? The wheel rim is just like a really huge annular ring.

I'm confused.
Using bike sprockets and chains, using coaxial spinning shafts, you could get say, a triple 52t to 11t gear multiplication in a space approximately like what is shown. You could end up with a useable gear ratio with the right size sprockets.......However, it would be at least as heavy as a geared drive train. On a concept bike I guess the price does not matter. It would be horrible to work on the thing. It would be a real head turner, but not something as good as the old Fuji.

This makes a traditional fixed gear bike look more and more attractive, lightweight, efficent, and cheap.

Sometimes reinventing the wheel is not an improvement. Maybe there is a reason the diamond frame, chain driven bike has been around so long.

Excuse me, I have to go out to the garage and admire my track bike for a few minutes.
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Old 08-31-05 | 08:03 AM
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Originally Posted by notfred
You could make it work the same way you make a double reduction gear work. You jsut have to package the whole thing inside that little housing around the cranks, which means you'd probably nead really narrow parts, especially since it looks like you might need a triple-reduction setup for a bike like that.
Of course!

Yeah, the key is to translate the motion at the axis of rotation, not the edge. As long as you're reducing through the edge only, any intermediate gears become nothing except frictional inputs. But when you tie a couple of gears together through their axis of rotation, voila, useful gearing!

Great! Someone get on it.
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