Prior to the 1990s, supermoto bikes, including the precursor motorcycles used in Superbikers, were converted open-class two-stroke motocross or enduro bikes desired for their light weight and jumping abilities. The motorcycles currently used for supermoto racing are predominantly single-cylinder four-stroke powered dirtbikes with , sometimes with front wheels. The wheels allow the use of up to superbike road racing slick tires. These are often hand-grooved on the rear tire to facilitate slightly better acceleration on the dirt stretches of a supermoto course. Suspension is lowered and slightly stiffened in comparison with a stock dirt bike, and braking power is improved with oversize front brake rotors and calipers. Despite the lack of trees on supermoto courses, hand guards are frequently added to supermoto bikes due to the extreme cornering angles achieved by riders. Hand guards also greatly improve survivability of the brake & clutch levers during a fall making supermoto bikes highly crash resistant and often able to quickly re-enter the fray during a race following a crash.