Keirin is a form of track cycling that originated in Japan. It involves a group of cyclists racing on a velodrome, where they follow a motorized pacer, known as a derny, for a few laps before sprinting to the finish. The race typically consists of six to nine riders, and the competition is known for its strategic elements and high speeds. Races are usually held over distances of 2,000 meters, and the event is popular in Japan, where it is also a betting sport. Keirin has gained international recognition and is included in major cycling events, such as the Olympics.