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Links/photos Of Concept Bikes Needed(not Just Trials)


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Right, I'm not lazy and have found several things already but I'm guessing there will be some concept bikes/components that i will have missed that could be of interest. Basically looking at designing a 'bike for the future' for my college project, i can get by on what stuff i have already but anything extra would be a bonus :) I have done the typical google searches and found several interesting things.

I'm really interested in alternative drive systems to the chain, and also different gear systems (hydraulic, air, and any internals other than rolhoff and shimano).

So any links to interesting ideas would be much appreciated, thanks!

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the old strumey archers gear systems (planeterial???? not sure) which are now being used in the truvativ internal gear sytem in their german design (it was an MBUK feature maybe just before christmas??)

not sure if tahts helpful or not but it is a free bump if it wasn't!

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The truvative system is called the Hammerschmidt. This is pretty much a cable operated version of a system called Mountain Drive (Again based on planetary gears in the chainset) that's been around for well over a decade at this stage. All internal gear hubs use planetary gear systems except for the CVT types, the only one in production for bikes is on some Ellsworth cruisers (Google NuVinci for more - I have serious doubts that this will carry decent torque and not suffer from hopeless efficiency or ludicrous weight (I'm pretty sure it's already very heavy), so useless for proper bikes).

A genuinely interesting system to look at (It's been demonstrated to work, though reliability is the big question) is the Torotrak CVT car/4x4 transmission or the hybrid mechanical/hydraulic drivetrain Fendt tractors use for CVT. The Honda DH bike had a derailleur system enclosed in a box located inboard in the bike frame to reduce unsprung weight and increase resistance to rock strikes/vibration. The GBoxx standard as pushed by Nicolai is another thing to look at as a platform for new bike drivetrains.

As for gear shifting, there's talk of Shimano releasing an electric derailleur soon, Mavic did this about a decade ago and it was complete shite from a reliability point of view and that was when used on road bikes...

I have a student working for me on designing an open system hydraulic gear shifter as a mechanical engineering project. A company called Red5 in Germany have a system claimed to be an open hydraulic system which retails (Shifters and derailleurs only), for about €1400 IIRC...

Other interesting drivetrains include the retro direct system - 2 gears, get one by pedalling forwards and the second by pedalling backwards, very devious stuff, invented in France over 100 years ago AFAIK...

One other very interesting system to look at is the rotor crank system, which eliminates the dead spot at top dead centre/bottom dead centre (TDC/BDC) by having the cranks move so the pedal that's moving upwards goes faster than the one that is being pushed downwards, meaning that when one crank is at BDC, the other is already past TDC... Animation explaining it here: http://www.rotorcranksusa.com/i1-rs4x.shtml

There's also some weird stuff like this: http://www.fact-canada.com/Powercranks/pow...ent-cranks.html which offers potential to work if pedaling efficiency is all you're after but you never want to stand up on the pedals...

Edited by psycholist
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Pneumatics tend to be very lossy though - unless the pneumatic system provides extra drive separate to the pedals. Pneumatics tend to have very poor efficiency in terms of giving back the energy the compressed gas contains as useful work.

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