Hey! So I just heard about Generator Hubs. I know that by definition it only works if its causing a little drag on your wheel, but has anyone used one of these for winter training, not just commuting/leasure...Just wondering. Seems SO eco-awesome! Any suggestions on brands etc?

I was thinking about this http://harriscyclery.net/itemdetails.cfm?ID=1547 but would need to then build a whole new wheel. Is that my only option?