I have now tried some of the best racing clincher tyres (Conti GP 4000S II), tubular tyres (Vittoria Corsa SC 320TPI) and tubeless tyres (Hutchinson Atom Galactik). In each case I wrapped them around what I felt was the best set of wheels I could build within a reasonable budget.
With clinchers there is a lot of buzz around the idea that a wider rim makes them feel more like tubulars than a narrow rim. This is barely true: if we say that a clincher on a narrow rim is 0 and a tubular is 10 then a clincher on a wider rim is about at 1 on that scale. If you’re buying some clincher wheels anyway then go for the wider rims, but “to get wider rims” is not a good enough reason to spend money on new clincher rims. And read on for why you shouldn’t be buying clincher wheels at this point.
It seems universally acknowledged that tubulars feel a lot better than clinchers to ride, and this is true. High-TPI latex-tubed tubulars are much better than any clinchers. I also tested high-TPI “open tubular” clinchers and latex tubes; they still felt like clinchers to ride. I’m told that low-TPI butyl-tubed tubulars feel worse than high-end clinchers and I can believe that. Other than the comfort, the main benefit of tubulars is you can run them at a much wider range of tyre pressures. You can use lower pressures than with clinchers because you are not dependent on the air pressure to attach the tyre to the rim, and you can use higher pressures than with clinchers because the tube is not going to try and rip the bead off the rim. The latter failure happened to me when I tried to test the open tubular tyre concept at the high pressures I use in tubulars for time-trialling on smooth surfaces (before you ask, I was 5PSI below the upper limit printed on the tyre). Lower pressures are useful on rough surfaces to allow the tyre’s deformation to soak up more of the bumps. Given the choice between tubulars and clinchers I would choose to ride tubulars.
Now onto road tubeless. As with the clinchers on a wide rim buzz there were a lot of people saying that they ride like tubulars. I was very skeptical of this, having tried the first rumour and found it to be a gross overstatement, so it took me a long time to get around to trying road tubeless for myself. As it turns out, they really are as good as they’re rumoured to be: I honestly thought they felt as good as the best tubulars I’ve used. You can ride lower pressures than with clinchers because the tyre bead is held on the rim on both sides by metal ridges, not just by air pressure. If you want high pressures you still need to be using a tubular. Given the choice of all three I would choose to ride tubeless because I’m more often interested in using low-pressures for comfort than high-pressures for speed.
My aero clincher wheels are tubeless ready, so I will convert them to tubeless at some point. I doubt that I’ll be buying any more clincher tyres. I will wear out my current stock of tubular tyres and then rebuild my tubular wheels with tubeless rims.