Originally Posted by
oldacura
We've climbed & descended most every paved mountain pass in the Colorado Rockies. Also climbed & descended Mt Evans & Mt Haleakala on Maui - all with rim brakes. Never had an issue. On a couple of occasions I became concerned that the rims might overheat (steep, winding road, hot day) and stopped to check the rims. They were hot but I don't think we were close to a blowout. While this is just our experience, there is no way to compare how this might have gone with disc brakes. I don't know if any of the teams out there have a more apples-to-apples comparison.
Do you recall how the descent on Haleakala was from the lower switchbacks (6000' to 3600')? That's the section of the marathon descent that would have me concerned the most regarding rim brakes on a tandem. Looking over my ride from 2012 I was averaging right about 30mph with a max of 39mph on the rental Trek I was using.