Hubless wheel

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A hubless wheel (also known as a rim-rider or centerless wheel) is a type of wheel with no center hub. To be precise, however, the hub is actually almost as big as the wheel itself. The axle is hollow, following the wheel at very close tolerances. The hubless wheel was invented by Franco Sbarro (who has built a variety of working hubless wheel vehicles, including at least two motorcycles and a car, the 1989 Sbarro Osmos ), and patented by Globeholding of Geneva. The wheel has yet to reach its full technical potential. Tolerances, transfer of energy, and materials are elements of the design which are yet to be fully exploited.

Although hubless wheels are striking in appearance, their numerous practical disadvantages have precluded their widespread use as an alternative to conventional wheels. They are difficult and expensive to manufacture, requiring a great deal of precision machining, and the design leaves the bearings and other mechanical parts largely exposed to the elements. The drive system is especially problematic since a conventional axle and CV joint cannot be used; options include using chain or belt drive. Another solution, developed by Sbarro, is to house the entire propulsion system inside the wheel itself.

An example of a hubless vehicle is the "Zero Bike", a lightweight hubless bicycle whose non working prototype won an Industrial Design Excellence Award in 1991.[1] [2] Its design is based on the principle of magnetic superconductivity, also used in high-speed trains that are suspended above rails.