Here is the deal. I have a 14yr old that wants to MT Bike race. There are only a couple races left in the season then there are a few Cyclocross races. I know....NOTHING...so I apologize for sounding like an idiot. My question is, for a couple of local races, can you take a cheap used road bike or a decent vintage road bike and create a serviceable Cyclocross racer out of it, or do you need a 'cyclocross' bike. we are talking Jr 13-15yr old class.