Originally Posted by aal
However, unless I'm wrong, I think a lot of triathlon bikes have even steeper seat tube angles than track bikes do, and people ride triathlon bikes for pretty long distances on the road. What am I missing?
Tri bikes also have pretty short top-tubes too. This is because you are on aero bars, and that makes putting your weight on the bars way more comfortable than if you were doing the same on non-aero-barred bike. Aero bars on a road bike will make you bend way the hell over, which is hard on your back, and your legs will still be going forward a bit. On a tri bike, your back isn't bent as much because the pedals aren't as far forward (steeper ST) and the aero bar thing makes carrying that weight on your arms that much easier.