Rolling resistance data seems to favour clinchers, and tubless.
People rave about the comfort of a tubular. Do they allow people to have a more comfortable ride (faster due to lower impedance/suspension losses) at higher pressures (better crr)? That is my guess, but do we have data?
Is it that they can take harder cornering forces at lower riding pressures without fear of failure? Or when a bike is limited to 15lbs... are they trying to minimize rotating weight? All the above?
I figure all the folks running continental tubulars that are only available to the pros must know more than we do. Or is a few crr when you are putting out an average of 400w really no big deal, and people are just stuck in habit? And I do not fully buy the habbit explanation, because it is too competative for people to leave free watts on the table.