A quick update!
Seems there are a lot of new things going on on the E-bike community: endless-sphere.com !
Adrian has done a friction drive (on tire drive, http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=22187&p=322985#p322985) with nice documentation. It makes it kinda possible to have something running quickly! he also has the sketch for the design (attached to this mail, probably needs acrobat reader for 3D viewing). you can see some videos of his design (each 30 sec. long):
http://www.youtube.com/watch?v=Sy7xtOJKa8E
http://www.youtube.com/watch?v=w79wNBCy5G8
http://www.youtube.com/watch?v=L_mPArb2018
Oh my, I am getting sunken into this 🙂