[changzuki]

The idea of a bicycle generator is a topic that often gets some attention here at 9 Main during a home tour. I've had several units (alternator based, permanent magnet motors, etc) and to generate power into a battery bank is not easy - this comes from someone who could at the time, generate 300 watts continuous for 2 hours. Most folks who are not dedicated cyclists will likely never see that type of output.
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A second unit exists but you'd never know it to look at it. This unit has the ability for the operator to recharge its on-board 48 volt lithium batteries by going down a hill and engaging the regen switch, or by jacking up the rear tire off the floor and pedaling:
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Like the in-house unit, this is not at all easy to do, but if you're in really good shape it can be done.
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A cycle generator is a fun project and it can get you in shape while making some small amount of electricity to charge batteries or run small appliances. Beyond that, don't expect too much.
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~CrazyJerry