It does seem odd, doesn't it, that heat dissipation would be a bigger concern on a clincher shaped all carbon rim than it would be on an equivalent tubular shaped all carbon rim. This isn't the first place I have heard it though. I read some similar comments on an old Weight Weenies thread recently that prompted me to raise the question in the first place. Maybe I will ask Waldo for some further clarification on the other thread.

Good point about races generally not including long, extreme braking sections, and Waldo himself did use the word "extreme" when he was referring to the EU braking tests. Most of my Utah rides don't include long, extreme braking sections, and I am only in Los Altos for about 5 days every six weeks, and realistically wouldn't have the new race wheels in California anyway for quite a long time.

So I am kind of coming to the conclusion that I might want to think twice about using all carbon clinchers on hot rides with extreme braking and I might want to think once about using all carbon tubulars on hot rides with extreme braking. This wouldn't be any significant limitation for me since I plan to do most of my training on aluminum clinchers anyway, and most of my rides don't have long, extreme braking sections.

That is great to know. I didn't know that before you mentioned it. Thanks.