I believe Bush bought the bike just this past Febuary. Which gives Kerry a bit of an edge since he has been riding road bikes for many years.
Bush likes to buy things to make him look like he is someone else. He bought his Texas Ranch just in time for the first Presidential race. You have to remember he is not a Texan, and he never was a rancher until it suited him.
One of his adviser probably told him that Kerry rides so he had better ride too.