Why to cyclists shave their legs?

Firstly, it's nothing to do with aerodynamics. There's a couple of theories, one is that it makes the job of the masseurs easier. Massaging hairy legs can't be pleasant and it's also apparently uncomfortable with some of the sticky oils. Also if you have a crash it's easier to clean the wound if it's clean shaven. According to a team masseuse I spoke to, a big reason is that it looks better when you're standing on the winner's podium. According to Matt Seaton, the main reason riders have their legs waxed is that it makes you look like a proper cyclist and everyone else does it.