Abarnes is right. The brake/wheel clearance on a road bike isn't sufficient for knobby tires needed to race 'cross. Additionally, the geometry of a 'cross bike is different - higher bottom bracket and a shorter top tube (typically).

You COULD use a mountain bike - better choice if you have one and are looking to give 'cross a try before jumping in to purchase a new bike.

But I'm warning you - once you try it, you'll be hooked .

SheFly