Funny, TPP first read the title of this article as "fly-weight bicycle", which sort of makes sense, but the real topic, fly-wheel bicycle makes great engineering sense too. The principle of a fly-wheel (the black thing in the center of the bicycle frame) to conserve energy, capture the energy from a moving object, and then use that energy to get the vehicle moving again is nothing new. TPP first remembers learning about this from trolleys in places that still have trolleys. And of course, fly wheels are used in hybrid car technology, but applying this principle to bicycles is very creative, which is what you want engineering students to be, because one of the big problems with using pedal-powered vehicles in an urban environment is that the frequent stops rob you of all the energy you used to get your vehicle up to speed. And unless you are one of those stupid bikers who like running through intersections as if the rules of the road don't apply to you (we think of them as incipient "hood ornaments"), stop you must, but the expenditure of energy to get going again is a bummer. However a fly wheel can capture than kinetic energy and allow you to reapply it to getting your bike back up to speed again. Now how can that get engineered into my semi-recombent bicycle?