I wonder whether it would be possible to build an asynchronous (induction) motor, using a Hottowtech II-type crank spindle as the rotor, just by adding the armature and windings around it. No moving parts added, no noisy gears. You wouldn't be able to produce a huge amount of power at such a low angular velocity, but even 10W continuously over the course of a race could well be the difference between winning or finishing in the bunch... The biggest problem I see would be getting rid of the heat generated in the spindle, to prevent the BB bearings seizing.