What are the rules for cycling olympics?

Bicycle racing started out as road races, and that has remained fairly recognizable over the years. People ride faster, team tactics have become more developed but that's the main points about road racing.

Then there was the track racing, the single events(time trial) as opposed to the group events that sprung out of road riding.

But as the bike developed into several specialized versions (BMX, MTB etc) these too developed their own forms of competitions.