A 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.

No 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.

Citation? 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.

What kind of citation are you looking for? This is just common engineering knowledge. The airtight safety housing alone would be way too heavy for bike racing. You can't have a flywheel spinning at zillion rpm sitting out in the open because it could kill someone in a crash. Plus the flywheel would need to be in a near vacuum to avoid air drag.

That'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?

It'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.

Actually, since about 5 years ago bicycle stability is pretty well understood: http://bicycle.tudelft.nl/stablebicycle/

Thanks!

Prof Ruina? I loved his class.

No, Dr Hunt (see link in cousin). I actually only had him as a tutor but didn't want to complicate things.

Ah. I see that now. I had Ruina for Dynamics, and talked a bunch with Jim Papadopoulos. Fun Times.

Bikes already have two really large flywheels.

And people spend a lot of money to make them store just a tiny little less energy.

Except when they are chasing the hour record. Ondrej Sosenka ran 3.2 kg wheels in his 2005 hour record precisely for the flywheel effect.

Every 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.

No 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).

They don't spin fast enough nor with enough mass to help you climb a hill ...

Or 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.