In this Thursday, Dec. 12, 2013 photo, a bicycle fitted with a prototype of the Copenhagen Wheel, the red disk, a human/electric hybrid bicycle engine, hangs on a wall at Superpedestrian, the hybrid ... more 
In this Thursday, Dec. 12, 2013 photo, a bicycle fitted with a prototype of the Copenhagen Wheel, the red disk, a human/electric hybrid bicycle engine, hangs on a wall at Superpedestrian, the hybrid engine's manufacturer in Cambridge, Mass. (AP Photo/Stephan Savoia) less 
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Associated Press | Photo By Stephan Savoia
Wed, Dec 18, 2013 2:25 AM EST