Energy return wheel that needs no air

    The wheel consists of a center layer of rubber that is stretched and held tightly by a series of rods, which can be adjusted for different types of terrain. The mountain bike version of the wheel includes 29-inch carbon fiber rims and is open on the sides, although it is being considered covering the opening with thin sidewalls to keep debris from getting caught in the tire.
    Besides eliminating the risk of flats, the wheel also helps increase performance by storing potential energy in the stretched rubber.