Science Forums 2

[CraigD]

Just throwing out some first thoughts, here’s what I’d try:
With whatever rim (true them – make sure they’re very close to round - first) and forks you have handy, some magnet wire, a couple of strong permanent magnets (the cubical shaped rare earth kind) and a small (ie: pocket size) multimeter, and whatever clamps and locking pliers you have
wrap a bit of the rim with a single layer of wire
tape the multimeter as close to the hub as you can
connect the wire ends to the multimeter
clam the magnets to the forks with a mm or so clearance for the rim
give it a spin and see what voltage the multimeter displays.

This, and max charging voltage and current data for whatever batteries you plan to use, should give you the data you need to scale it up to the needed power.

Ultimately, I imagine you’ll want to epoxy and autoclave cure wires into/onto something like a 4-spoke carbon fiber wheel/rim, and use some sort of brush commutator near the hub to get the current to the battery. It would be really nifty if you could manage some way of doing it brushlessly, via inductance (the wheel will, after all, be moving most of the time), but that seems a lot more complicated to me.

Remember, you still want the bicycle to have good performance as a bicycle, so keeping wheel mass to a minimum, especially near the rim, is as important as ever, which to my thinking rules out permanent magnets on the wheel schemes.

Good luck and post pictures!