Different types of events like in the track cycling. So there's time trials, fastest time wins, and group events there are several riders that race together in a heats and then finals. The time trials go towards the seeding and order for the group event
The impression I got from watching it at the Beijing olympics is that it's an atrocious sport. Seemed to reward the ones that go slower and stay out of trouble when the group in front crashes. The number of races that were won by people that were in last place for 80% of the race only for a massive crash to hand them the win was ridiculous.