Originally Posted by chefisaac

gaz: how long have you been commuting? Could be your quads are tearing and building up. Also, what I used to do is rub them down starting from the top of my knee toward my quads. Could be acid build up. The rubbing is painful and all you are doing is trying to move out the lactic acid.

I also find that if I ride a long distance on the weekend, the following day I take a walk. Works for me.