Jennifer Holt, currently a physics grad student at Ohio State, made this motorized mountain bike herself–she even made the frame so it could hold all the components.  Check out her website, JennTech, Science From Scratch, where she’s posted more specifics, pictures of the electronic parts, and will soon post the schematics for the bike with its 48V motor and homemade lithium battery pack. She limited the top speed to 30mph, and admittedly isn’t very good at riding it yet–she’s already fallen off and broken her elbow. Video of it in use (pre-broken elbow) after the break.
