I have been looking into building a low rpm generator to recharge batteries, run lights, recharge GPS etc. Just wanted to share what I have found out so far. https://www.surpluscenter.com/home.asp?UID=2348022115295908 This is a great site for electric motors to use as a generator with many low rpm motors. I am thinking about coming up with a speed multiplier (basically a reverse gear reduction box) to take wheel rpm and increasing it to a more efficient range for use with the generator. Also found this https://www.surpluscenter.com/item.asp?UID=2348022115295908&item=5-1676&catname=electric It has a speed controller that I think could potentially be used to decrease motor/generator rpm's so you wouldn't need the multiplier. I looked at the hub generators and while I like them I would like to be able to disengage it if I'm not recharging or powering anything. Would love some ideas, comments or opinions from all the inventive folks on here.