Ive heard a bit about this sport, never seen or really discussed it with anyone either.
Do you just take a racer and stick on some thicker tires with tread and go off-road?
Wouldn't this just ruin the forks?
Probably a stupid questions that everyone asks but im just curious, an explanation would be much appreciated
Cyclocross bikes USED to be just a road bike with knobbies on.
Then road bikes started getting built with a lot tighter geometry in the late 70's and early 80's. By the 90's you couldn't fit a knobbie CX tire into anything but a Bridgestone. Then none at all.
So you now need a CX bike and fork which are built with about the same clearance as a 1975 Peugeot but the steering geometry of a 2005 Raleigh Team road bike.
Off-road shocks from striking potholes and the like are no worse than on-road shocks from hitting pot holes and the like. What's more, the fatter tires cushion the wheels somewhat and you actually get a softer ride.
homemade cyclocross, 2005 KHS Flite 100 frame + assorted parts
Most new road frames won't even come close to clearing a fat 'cross tire that you'd want for a comfortable ride (there are narrow tubeless cyclocross tires that probably would fit). Also they lack the cantilever bosses on the frame and fork for mounting cantilever brakes or v-brakes. You need these off-road brakes with enough clearance to keep from getting clogged with mud. You could have these brazed onto a steel frame but often the chain stays are to narrow to properly mount a rear brake. So you're left with two options- Use an older road or touring frame (like the '75 Peugot mentioned) possibly with canti bosses added or use a modern 'cross frame. In my opinion the differences, beyond weight, are minor but there are some. Cyclocross frames tend to have slightly higher bottom brackets and so on. Really the main difference between a road and 'cross bike is in the tires. The fatter tires make for a much nicer ride.