> What do you mean by self-sufficient? Of course, some energy input
> will always be needed (even if it is only human power). I'm guessing
> that you mean a system which can efficiently absorb all of the
> regeneration from braking and deliver it again when power is needed

Yes. The disadvantage I'm seeing with some of these systems is that
the motor can't be used (or, rather, has not been designed) to convert
kinetic energy to charging energy, or even to just disengage the motor
to reduce pedalling effort, eg if it happens to be a permanent magnet
motor with significant cogging. I remember the bad old days of a tyre
dynamo. I suspect many of the motors are permanent magnet, as the
manufacturers advise about magnet corrosion. You might actually
expend more energy, for example if the batteries are drained early on,
depending on the terrain during the journey, based on the experience that
it's always easier to get current out of a battery than put it back in

Joe

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