Hmmm...interesting.
"At first glance, a proposal to replace a bicycle's familiar chain and cog drive with one that uses string may sound like lunacy, but that's exactly what's been done to produce the Stringbike. The system features freewheel mechanisms on either side of the rear wheel connected by polyethylene rope to a precisely positioned, symmetrical swinging arm that drives the bicycle forward. When the unit on the right is driving the bike forward, the other is being returned to its starting position and vice-versa which is said to result in greater efficiency and makes for a more comfortable, easier ride."
Read more: Going chainless with the Stringbike
