Road Racing World Championship Grand Prix is the premier championship of motorcycle road racing currently divided into three distinct classes: 125cc, Moto2 and MotoGP. The 125cc class use a two-stroke engine while Moto2 and MotoGP uses four-stroke engines. In 2010 the 250cc was replaced by the new Moto2 600cc four-stroke class. Grand Prix motorcycles are purpose-built racing machines that are neither available for purchase by the general public nor can be ridden legally on public roads. This contrasts with the various production categories of racing, such as the Superbike World Championship, that feature modified versions of road-going motorcycles available to the public.