That's already been done. It was called the "Copenhagen Wheel". Cool idea for someone who makes short trips in rolling hills. For long straight rides like I've got here, I don't know what good it would do.
I really think E-bikes are the future. So many really gifted folks working on bringing them to market and the batteries are getting better and better.
LOL, if I am right, just blew $17,000 on edumacation, tools and a shop.
http://news.cnet.com/8301-11386_3-5...bicycle-wheel-gives-riders-electric-momentum/