How to propel an average-weight bicycle with +250lb/113kg rider using a DIY hub dynamo?

I want to make a hub dynamo (DC motor in wheel’s center) for a non-electric bike. I’m just getting started with this project; I don’t even have a bike to use. I figure that with Faraday’s law (Google it), a few old Lithium-Ion batteries, copper wire, electromagnets, &etc, I should be able to make a DC dynamo that might be able to assist with pedaling (electric pedal assist). If anyone knows for certain if this isn’t a worthwhile endeavor, don’t hesitate to inform me.

I think your main problem will be that the average hub dynamo is designed for a low power (about 10 watts). The other motors available for powering bikes are between 200 to 300 Watts. I doubt the wire in the dynamo will be sufficiently robust to do the job you want.

As well, the motors available are of a completely different design, optimized for traction. Hub motors rotate at the same speed as the wheel. This means it is difficult to use gearing to improve the torque. There are designs of motors that can develop good torque at low rpm but I are likely to be expensive.

This guy has some good ideas:

http://www.electricycle.com/

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