Originally Posted by merlinextraligh

I just got done doing a bunch of hills in WV on Zipp 404 Firecrest carbon clinchers. Many of the hills were twisty with as much as 20% grades, and a lot of grades in the low teens.

Had no issues with the rims or braking. Admittedly all of these descents were relatively short, in the 500 vertical foot range.

Personally, I might steer away from carbon clinchers if you're doing really long descents, and are the type to ride the brakes. I'd also likely avoid the no name rims for mountain riding in general.