Unlike other bicycles, the StringBike is driven by steel string drive units. In technical speak, it “uses two identical but opposing drive units on either side of the bike which feature swinging arms moving forward and back as the pedals are turned; this back and forth motion pulls a set of steel ropes on either side which in turn cause a drum and the rear wheel to rotate.” Videos after the break.
Since the mechanisms on both sides are moving in symmetry as you pedal, the rear wheel is constantly being driven, providing a smoother, and more efficient, ride.
[via OhGizmo]