Cyclocross frames are very similar to road bike frames in design. One of the key differences is that cyclocross frames are often made with steel, which provides a more reactive and soft ride compared to aluminum tubing. You will find some cyclocross frames built with carbon tubes, but these are few and far between. Most cyclocross bike setups will include a rigid fork. It turns out, that is the general preference for cyclocross bike racers over front shock forks. Often times, a road frame can be repurposed to be used for cyclocross riding - they really are so similar in terms of geometry and ride characteristics. Cyclocross frames, though, are usually designed to accommodate cantilever or side pull brakes instead of caliper brakesets. One key measurement to keep in mind is the bottom bracket height, since this will determine the ground clearance for the finally built up cyclocross bike with cranks and pedals installed. Surly is one of the leading brands of cyclocross frames with several choices at a range of pricing.