Small-capacity

Small-capacity sport bikes typically have engine sizes ranging from 125 cc (7.6 cu in) to 400 cc (24.4 cu in), but are also produced in as little as 50 cc (3.1 cu in) (sometimes designed/tuned for persons carrying a restricted/learner's license). Small-capacity sport bikes are available in both 2-stroke and 4-stroke cycles, although production of 2-stroke sports bikes has diminished due to tight emission laws and agreements. Generally small and light, they can suit the shorter rider; the light weight partially offsets the performance drop due to their lower power. Short wheelbase and lightness means handling characteristics are often on par with that of the typical high-capacity sport bike.

Also relatively new but gaining popularity is the new 450 super single class. A 450 Super Single is a single-cylinder 450 cc dirt bike that has been converted into an entry-level road racer. The frame, subframe, swing arm, motor and transmission are all stock, but the wheels, tires, suspension and bodywork have all been modified for on-track use. These bikes are also being modified in Australia for street legal use and are the fastest restricted/learner legal bikes available as the current laws prohibit 2-stroke 250 cc bikes.