Welcome to BikeRadar's guide to the keirin, one of the six events that will be raced on the velodrome at the London 2012 Olympics.
In the following video, we've teamed up with 1992 Olympic gold medallist Chris Boardman, who explains the nature of the keirin and how it's won.
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Video: Keirin- track cycling event guide presented by Chris Boardman
What is the keirin?
Both men’s and women’s keirin is conducted over eight laps of the track. The riders are paced by a motor pacer, or derny, until around 600 metres from the finish, at which point the pacer pulls off and the riders sprint for the finish.
Once the derny pulls off it's every man for himself
Rules of the kierin
Riders line up on the start line with their positions drawn by lots. The pacer approaches on the inside lane at 30km/h (25km/h for the women’s race) and the riders join behind. The bike reaches a maximum of 50km/h (45km/h women) before pulling off the track with 2 ½ laps remaining. The first rider to cross the finish line is declared the winner.
The event starts with heats at the Olympics with the best 12 riders progressing to the second round. The top six then go through to the final with the bottom six competing for 7th-12 places.
Kierin in the Olympics
While keirin was only accepted onto the Olympics programme at the 2000 Sydney Games, it’s been big business in its country of origin Japan since the 1940s and is one of the main avenues for gambling in the country.
Britain’s Sir Chris Hoy will be back in London to defend the title he won in Beijing while for the women, it becomes an Olympic discipline for the first time.
Rider clashes are no longer allowed in the keirin
