From ibikeu Wiki

Track racing is a type of bicycle race held in a special banked track facility called a velodrome. Track racers use fixed gear bicycles with no brakes as they circle laps at high speeds while trying to muscle past other competitors. The track itself is generally either made of wood or concrete. In Japan, keirin, a variant of track racing involving a pacesetting motorbike, is extremely popular with the public, as is the legal parimutuel betting on the sport.