A pro would realize they are doing an alleycat and get on some ridiculous training regime that would allow them to learn the streets, get used to all sorts of traffic, build the propper muscles for the situation, find the right equiptment, etc. and then destroy everyone. That's why they are pros, not because they can ride bikes real fast.

Unless you mean they just magically pop up at an alleycat with no planning whatsoever, in which case they probobly would still crush. But this just wouldn't happen, or they arn't a profesional.