Athletes with the most significant impairments who ride a standard bicycle, such as severe coordination problems or major limb impairment.
The C1–C5 sport classes are for athletes who compete on a standard two-wheeled bicycle. C1 is for riders with the highest degree of activity limitation in this group. This typically includes athletes with severe hypertonia, ataxia or athetosis (for example from cerebral palsy), or significant combined limb impairments. Lower numbers mean a greater impact on cycling performance, so a C1 rider is more impaired than a C5 rider. Riders race against others in the same class, and across classes results are compared using the UCI factoring system.