Basics - Stages

Terrain
There are 4 types of terrain:
Flat

They pose no major problem. They usually finish in a sprint because the absence of any difficulties means that it is impossible to disrupt the peloton, which reels in any breakaway riders before the end of the stage. These are key stages for the green jersey.
Hills

These are characterized by a succession of rises and short climbs spread along the length of the stage. These stages are wide open because breakaways have more chance of going all the way. They also favour punchers and climbers.
Medium Mountain

These are difficult stages with mountain passes that are not to be under-estimated. They are sometimes more difficult to control than the major mountain stages due to terrain that can suit more riders!
Mountain

These are the most prestigious stages, that only climbers can hope to win, unless a breakaway manages to hold them off. It is on these stages that riders who vie for the general classification try to create gaps on their rivals. They are also vital to any rider who is aiming for the polka-dot jersey.
Cobblestones 

Independent of the terrain, there are also races with cobblestone sectors, which are most often encountered on the flat. Cobblestones require significant agility as well as a solid physique, if a rider is to lose as little time as possible.
The various sectors are displayed in grey on the stage profile.
In PCM we use 4 colour codes for cobblestone stages: green (easy),
yellow (normal),
orange (difficult) et
rouge (very difficult). For example, Paris-Roubaix is categorised as "red" with more than 50km of cobblestone sectors, of which some are in a bad state of repair.