Tour de France 2012

I still think Froome will move next year and he will be a pale shadow of the rider he has been, and perhaps deep down he knows that, and that his why he wants to make hay while the sun shine with as many stages as possible.

How do contracts in cycling work: he's signed a four year one apparently. If he wants to move to another team does he/they have to buy him out of it? Or will he have a get out clause? Or is it simply a question of resigning?