Originally Posted by Dave Mayer

As per my earlier post, the main negative of clinchers (tubeless or otherwise) is the 2 'hooks' at the periphery of the rim required to hold the tire on. These are heavy, fragile, and cause pinch flats. Tubular rim profiles are rounder and therefore it is almost impossible to pinch flat a tubular tire. I've done it (once), but that required hitting a fist-sized chuck of metal in the dark at warp speeds, which immediately killed the tire. The rim was OK; if I'd been on clinchers, I'm sure this would have killed the rim, the tire, and then me.

So on clinchers, the tire has to have enough effective volume and air pressure to make sure that the tire does not bottom out on the rim and cause damage or a pinch flat. But on tubulars, since the rim is stronger and more resistant to impacts, and because you don't get pinch flats, you don't need as much air volume. So you don't need fat tires, and all the extra associated weight, higher rolling resistance, and increased aero drag.

On tubies you can run smaller tires at lower inflation pressures, which I think is why folks are feeling that tubulars are more 'comfortable' and 'supple'.

Anyway, just more observations as to why clinchers are a sorry distance second choice to tubulars. Good for training wheels and beater bikes, but not for go-fast riding. Tubeless? I suppose if you live in goathead country, but for a road bike, tubeless features even more negatives than regular clinchers, and makes little sense.