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It's hard to disagree from my own perspective of a commuting cyclist who would like to see racing drive cycling advancement in ways that trickle down to afforda
by harlanlewis 11y ago
It's hard to disagree from my own perspective of a commuting cyclist who would like to see racing drive cycling advancement in ways that trickle down to affordably solving the last mile(s) problem for the human race, but allowing more than a single human as the source of power would simply transform the sport into something else. It's not necessarily better or worse, but using a motor is a fundamentally different activity and begs all sorts of arbitrary dimensions/mass/power restrictions or else it turns into a motorcycle race. There might not be a more efficient animal than a human on a bicycle, but we don't hold a candle to a Ducati.
- greggman 11y agoWhat about a flywheel? Probably a net negative. What about a motor with no battery. You pedal to power it? Just wondering what the limit of "human powered" is
- paulmd 11y agoA clutched flywheel would probably be an advantage in many kinds of terrain. Imagine being able to spin up the flywheel from pedalling or gravity (geared) while going downhill, and then when you hit an uphill section you kick in the gear and pedal easy. It would essentially turn most tracks into "flat" tracks.
- nradov 11y agoNo the extra weight of a flywheel plus motor/generator would far outweigh any small advantage. The energy density is just too low for any flywheel small enough to fit on a bike. And the gyroscopic effects would mess with handling.
- jacquesm 11y agoBikes already have two really large flywheels.
- Ensorceled 11y agoThey don't spin fast enough nor with enough mass to help you climb a hill ...
- usrusr 11y agoAnd people spend a lot of money to make them store just a tiny little less energy.
- wycx 11y agoExcept when they are chasing the hour record. Ondrej Sosenka ran 3.2 kg wheels in his 2005 hour record precisely for the flywheel effect.
- usrusr 11y agoEvery tiny acceleration derived from a pedal stroke has to be transferred from bike to rider by hands and back. It's not "work" in the physical sense if you look at the bike as your frame of reference, but it requires biological effort nonetheless. As long as you don't need to brake, more storage in the wheels is better. This effect would be strongest in a climb, but there you certainly only want heavy wheels if you can compensate with a lighter frame or parts (and if the inevitable braking on the subsequent descent does not call for less storage). But there's a catch: even on a track, lighter wheels will _feel_ faster, because you get stronger feedback from oscillations I'm your pedal stroke.
- nradov 11y agoNo matter how heavy you made the bike wheels, any kinetic energy stored in them would be used up in the first few meters of a steep hill on any road course. Then you have to drag those heavy weights up the hill. So no, more storage in the wheels isn't better (outside of a totally flat track).
- lmm 11y agoCitation? Flywheels can be very efficient especially with modern engineering. And it could be oriented so that the gyroscopic effects were stabilizing or destabilizing as desired, plus I think in any case riders would adapt quickly - I ride a "twitchy" bike with no front fork sometimes, and my old professor built a bike with a counter-rotating flywheel to disprove the myth that cyclists rely on gyroscopic effects to stabilize them.
- hardlianotion 11y agoThat's really interesting about the gyroscopic effects myth, as it is one I strongly believe! Is there some documentation of the bike or some analysis of this I can read?
- lmm 11y agohttp://www2.eng.cam.ac.uk/~hemh/gyrobike.htm http://www2.eng.cam.ac.uk/~hemh/gyrobike.htm
- hardlianotion 11y agoThanks!
- wutbrodo 11y agoIt's not a myth that gyroscopic effects contribute to stabilization, but rather that it explains the stabilization fully. It's usually phrased as "scientists still don't understand how bikes work [in terms of their stability]", which is pretty amazing if you think about it.
- fanf2 11y agoActually, since about 5 years ago bicycle stability is pretty well understood: http://bicycle.tudelft.nl/stablebicycle/ http://bicycle.tudelft.nl/stablebicycle/
- wiredfool 11y ago
- grahamburger 11y agoOr a motor + battery but the battery has to start discharged. Basically the same as the flywheel I guess, except you have a little more control over when the energy you store gets used.
- pge 11y agoAs a fellow cycling commuter, I agree with your sentiment,but I would argue that the rules of cycling racing now prevent a much more innovative environment that could trickle down to us commuters. In particular, the frame shape limits that keep everything as a double diamond. For efficient human power, the best designs are usually recumbents, but very little money has gone into that area because recumbents are not allowed in races.