Originally Posted by
ljsense
But if 700x25 works, yeah, go with a rim brake frame for sure. You can lock up your tires with rim brakes just fine, or feel your way just short of that point and stop as fast as tires allow. Pro riders have done descents on rim brakes that a normal person wouldn't do on twice the time regardless of brake type. And if you're thinking I've missed the point -- the brakes are to slow you down, not make you go faster -- that's not how racing works.
The video below is a good balanced watch for anyone considering disc vs rim brakes on alpine descents. It even addresses the point about some pro riders still being competitive descending on rim brakes. It's true, but only if you have the skills of Nibali or Pogacar. Most people, including a lot of pro riders, are going to be safer and faster descending on disc brakes and especially in the wet. Also good brakes tend to make you faster overall, as shown in the video. Putting crap brakes on an F1 car doesn't make it faster.
Note: The guy in the video actually bought a rim-braked Pinarello a couple of years ago because he thought the weight (for pure climbing) and cost saving (his rim-braked frame was heavily discounted) was more important than the braking performance. I wonder how he feels about that now in hindsight? It probably depends on how much steep/technical descending he does and how he feels about more limited tyre clearance.