Forget all the reasons that are apparent to race tubular tires, better ride, better cornering, more supple, etc. One of the main reasons to ride them that is hardly ever mentioned is that they stay on your rim when they go flat. I hate riding fast descents on clincher tires. I always have this thought in the back of my mind that there is a chance that I’m going to flat and if that happens, I would probably fall. I never have that thought on sewups.
Everyday here in La Jolla, I descend a road named Via Capri. It is steep and curvey. With lots of cracks and some potholes. I love it. But, that being said, it is pretty dangerous. Lots of slow cars descending to pass and lots of other car coming out of side streets. I try to have a max speed of just over 50 mph at the bottom. It is hard because there is a sharp left turn that you have to really jam the brakes on to negotiate.
This morning I noticed my rear tire was showing threads. I don’t have another tire, so I put it on my front. Anyway, I was not big at all going that fast, cornering, with bare threads showing. I still got over 50 going down, but it wasn’t an easy 50. I was thinking it would not have been a problem on tubulars. In a perfect world, I’d only train on sewups.