Originally Posted by
nfmisso
For Slow speed descending you need something other than just rim brakes - unless you enjoy blow outs...... Rim brakes can heat the rims so much that the tire blows out. Given your light team weight, the addition of a 90mm SA drum hub on the front might do it.
Fixed that for you. What really heats brakes is going down steep hills, at a pace below what gravity dictates. If you're braking repeatedly, or for prolonged periods on the straights, you're going to have heat issues, and may need a drum, or a supplemental disc brake.
But if you're letting the bike run, and only braking for turns, you don't have the same heat issues.
When we did Haleakala on Maui, the tour group we were with made us put a rear disc on. I guarantee you we would have made it down with rim brakes alone with no issues. While some in our group had to stop from overheating their discs, our brakes never got significantly hot.
The difference is we were hammering in the 53/11 down the straights, seeing how fast we could go, and only touching brakes briefly before the entry of most turns, and some not at all. Those teams that were going slower and repeatedly braking had issues.
So it comes down to a question of how you descend.
The OP team being two racers, I'm betting descend using the brakes less than the average tandem team.