Originally Posted by schnee
K, I get it, but why are cyclocross top tubes all so short in relation to other road bikes? Is it to force a more upright riding position?
If you will be riding your cross bike on the road, then it makes sense to set it up like a road bike. But if you plan on riding it off-road, you'll find yourself constantly working yourself to more upright on the bars when you get into the trails and bumps. Pretty decent rule-of-thumb for cross bike fit is one cm shorter TT and one cm shorter stem than your typical road fit. With that in mind, cross bike stock TT's will typically be shorter than road.
Another thing to keep in mind, cross bike sales aren't as strong as road sales. Size runs of each model aren't going to be as extensive, so bigger sizes might miss out as a result. For instance, Trek only offers five sizes in their XO cross model (w/ max TT length of 56.5!), but seven sizes in the Madone. Check out the Jamis Nova,
http://www.jamisbikes.com/usa/bikes/07_bikes/nova.html - seven sizes in a steel frame, w/ max TT of 60cm. Great line of bikes.