I have worked on these, and they are, at best, a mechanic's minor nightmare. The shifting of the variable diameter "chaniring" is problematic, somewhat imprecise, and tends to wear easily, as it relies on plastic parts to provide indexing. The rear brake requires a unique rim that I have only seen on this bike, and the cable does wear the portion that it rubs against (the "braking surface" if you will). I have no idea how long it is likely to last, but it is guaranteed to eventually cut through the extra flange on the side of the rim, detaching that piece and leaving the rider with no brakes at all. There is some interesting and innovative thinking involved in this bike, and it would be fgreat as a prototype used to assist the design process. As a a finished product, not so much.