(Say: Kay - rin) - Keirin is a mass-start track race which originated in Japan as a betting event (sort of like horse racing with humans) and is now also an Olympic event. In traditional Keirin lots are drawn to determine starting positions and 6 to 9 sprinters compete after a paced start. The pacer starts at a slow 15 mph and riders are required to remain behind him. The pacer gradually increases speed and leaves the track approximately 600 to 700 meters before the end letting the racers sprint to the line. The first person across wins.