The motorcycles concerned are either 750cc four-cylinder or 1000cc twin-cylinder machines (900 cc triples are permitted, but at this stage only Benelli and Foggy Petronas - both very small companies - have run them) and weigh approximately 160 kilograms. The frames (and engine blocks?) must be identical to the production bikes, but other components are free for extensive and expensive modification.
The category is highly popular with manufacturers, as they can sell their road motorcycles as the basis for their race-winning superbikes. There is a World Championship series and an American championship, as well as British, Canadian, and Australian series.
There is a variant of the concept called SuperSport which involves slightly smaller bikes with more restricted modifications. Typically, the SuperSport class consists of 600cc motorcycles.
The series' future, however, is somewhat uncertain at this point (October 2003), with the reintroduction of four-stroke motorcycles to the Grand Prix racing series and frequent rule changes.
The most accomplished Superbike racer is Carl Fogarty of England.