derny

Derny is a motorized bicycle used to pace riders during motor-paced track cycling events. The device combines a standard bicycle frame with a small internal-combustion engine and a drive system that powers the rear wheel. A pacer sits on the machine and controls speed, steering, and position, while one or more cyclists ride in a line behind the Derny, drafting to gain speed.

Design and operation: The engine is a light, typically two-stroke unit mounted on the frame. Power is transmitted to the rear wheel by a chain drive, allowing the pacer to set a steady pace. The pace line forms behind the Derny, with riders maintaining a prescribed following distance. The Derny’s presence reduces air resistance for followers and enables high speeds around the velodrome.

Racing context: Derny-paced events take place on velodromes and are governed by track cycling rules. The pace is adjusted to the abilities of the riders and conditions, with speeds on the straightaways commonly ranging from about 40 to 70 kilometers per hour. These events appear in various formats, including endurance and sprint-paced races, particularly in national programs and certain international competitions. The Derny has become the eponym for this class of motor-paced pacing bicycles, produced by several manufacturers, and remains a recognizable element of traditional track cycling.

See also: Motor-paced racing, Velodrome, Track cycling.