I moved to Colorado this year and rode my steepest descent today. ~10% down a windy road. Having not ridden this before, I was pretty nervous going down, so I bled off quite a bit of speed (averaged about 35 mph on the way down with heavy braking). I was worried about heating my rim and blowing off my tire. Has that ever happened to anyone?

I know Disc brakes can fade due to rotor heating. Does anyone have feelings about which potential failure is more likely, rim brake heating causing tire failure or disc brake heating causing loss of braking?

Thanks!
Alan

Yes. Everyone. does. Have feelings. About rim vs disk.

Would you like some crackers to go with that can of worms you just opened?

Lots of touring bike have rim brakes. They can be very heavy: 300lbs with luggage and rider. They can go down some pretty steep grades with sharp bends where they need to be on the brakes constantly. Or if they are ridden by someone like me, let rip to see how fast they can actually go (50mph as it turns out, if the grade is steep enough) then some ludicrously heavy braking for the next bend Nothing happens. Rim brakes or disc brakes, fit good pads to either and ride it like you stole it.

Best thing you can do is restrict your braking to just before corners and then brake at close to 100%. This will allow you to use aero drag to absorb most of the energy as you descend. You'll end up going faster on the straight stretches but your brakes/rims/discs will stay cooler.

If you're not too heavy and don't mind a bit of speed you shouldn't have any problems with normal rim brakes.

Hello there, I am of the not-so-informed opinion that rim brakes are fine They certainly have been fine for me, both on some pretty steep downhills and for a _very_ rainy 8-hour ride (100-miler in typhoon Japan weather LOL). But as to your question:

"I was worried about heating my rim and blowing off my tire. Has that ever happened to anyone?" I was recently in a GranFondo, and there was this guy right in front of me with carbon wheels going downhill on a pretty steep incline. There was a safety motorcycle escorting us (there had been an accident ahead), so we had to keep constantly on the brakes. Unfortunately for the carbon-wheel guy, his rear tire blew up

If I ever switch to carbon wheels (unlikely, though it's just a personal preference), I would also switch to disc brakes for this reason alone. I read on this site that rim brakes on carbon rims can lead to this very situation easier than with aluminum rims.

For what it's worth

Geoff

I do a lot of descending and I'm over 200 pounds. I have had those 'peel and stick' patches come off due to heat, but have not experienced a tire failure from heat.
My current bike has Mavic caliper brakes with Dura Ace pads and they seem to work better than most others I have tried. I like to switch between the front and rear brakes when I can and give them a chance to cool. Rim brakes can fade, even the canti-lever kind.

I assume it was a clincher rim? Did the resin soften and allow the tire to push the beads outward?

I've blown three tires off rims on our tandem from brake heating. Not dragging them either, just hard application coming into a corner or stopping at a light at the bottom of a hill. That was with Velocity Aerohead rims, similar to an Open Pro. Changing to deep section alu rims like Velocity Deep V or Kinlin XC 279 fixed the problem. Never happened again. ~280 lb. team at the time.

For the example in post 5, I would have simply stopped and let the "safety", i.e. danger moto go on.

I prefer SwissStop green or blue pads for alu rims, while their Black Prince pads are reported to be best for carbon.

With proper technique, rims, and pads, rim brakes work fine. On a famous group tandem descent on Mt. Ventoux, all the disc equipped tandems had issues. The only bikes to descend without issues had rim or rim/drum brake combinations. There is reason to believe that the rim brake tandems were simply more careful.

Sorry... I didn't take that close a look All I know is they were rim brakes and carbon rims

Geoff