The Copenhagen Wheel, turns an ordinary bicycle into a smart electric hybrid by simply replacing the back wheel. By storing downhill, peddle, and braking energy in the wheel hub, and releasing it on hills or when tired, the Copenhagen Wheel makes long distances short and steep hills a breeze. Folks will no longer have to arrive at work covered in sweat! The first commercial version of the Copenhagen Wheel can now be pre-ordered. Price: $700 and no doubt half that price as soon as knock-offs start appearing from China and India.