<Tr> <Th_colspan="2"> Presence </Th> </Tr> <Tr> <Th> Olympic </Th> <Td> 2000, 2004, 2008, 2012, 2016 </Td> </Tr> <P> Keirin (競輪 / ケイリン, (keːɾiɴ))--literally "competition ring"--is a form of motor - paced cycle racing in which track cyclists sprint for victory following a speed - controlled start behind a motorized or non-motorized pacer . It was developed in Japan around 1948 for gambling purposes and became an official event at the 2000 Olympics in Sydney, Australia . </P> <P> Races are typically 1.5 kilometres (0.93 mi) long: 6 laps on a 250 m (270 yd) track, 4 laps on a 333 m (364 yd) track, 4 laps on a 400 m (440 yd) track . Lots are drawn to determine starting positions for the sprint riders behind the pacer, which is usually a motorcycle, but can be a derny, electric bicycle or tandem bicycle . Riders must remain behind the pacer for 3 laps on a 250 m (270 yd) track . The pacer starts at 30 km / h (19 mph), gradually increasing to 50 km / h (31 mph) by its final circuit . The pacer leaves the track 750 m (820 yd) before the end of the race (3 laps on a 250 m (270 yd) track). The winner's finishing speed can exceed 70 km / h (43 mph). </P>

What is the point of the keirin bike race