Engineer Carl Morgan's son complained that a certain hill was too hard to climb on his bicycle. Could his dad invent a machine to help him power over these inclines? The answer came in "Joules", an electrically-powered robot that rides in the back seat of a tandem bicycle:
Morgan spent months modeling how to transform a motor’s spin into pedal-pushing legs. The motor inside Joules’s torso turns a series of linked belts and chains that transfer power from one area of the robot to the next. Each upper leg pivots at the hip, raising and lowering its knee and forcing the lower legs to turn the pedals. He also added “bones” (rods on the outside) for needed stiffness.
Morgan was nervous when he climbed in front for the final test, but Joules easily cruised to the top of the hill. The bike could probably do more, even hit 30 mph, but Morgan says he doesn’t plan to find out: “Abject cowardice on my part means we’ll never know for sure.”
http://www.popsci.com/diy/article/2009-12/robot-buddy-your-bicycle-built-two | Official Website