The Frii, created, by Dror Peleg, truly is the bastard child of an exercise bike and my childhood big wheel. But what set its apart is its "flat-tire proof" tires, shorter fork, and ribbed body for extra strength.
Peleg designed this Frankenstein bike using recycled plastics and injection molding technology, all with strength and customizability in mind. So, while its not winning any beauty pageants, it could probably take a good beating. [designboom]