Super sketchy overheating disc brakes

[waswerte]

I did a steep descent (1100m at 13% with pinches up to 29%) yesterday, where you couldn't go faster than 20-30kp/h, so I had to drag my brakes constantly. At some point my brakes started "stuttering" and giving out almost completely.
I weigh 82kg and it was 35°C, so ideal conditions to overheat my brakes.

Today I descendet a smaller hill and the brakes felt weak, almost as if the pads are comletely worn, and they squeelt like crazy, which they have never done before.

I run Rival AXS with two 160mm Quaxar Lynx rotors and the stock organic pads. I last bled the bike a few months ago, so that shouldn't be a problem. I don't have a caliper with me, but the rotors shouldn't be worn already, they are just over 4000km old.

Do you guys know if this setup is safe to run for the rest of my vacation, or if not which part should be replaced?

[Ypuh]

Did you take out your pads for a quick look? They might have been wearing off in an angle, or just glazed a bit so rough them up with some sandpaper.

There's 10+ things that could be wrong though. Like you said, all the ingredients (except for rain maybe) for accelerated wear are there. I've switched to disc brakes last year and unsure if I'm that happy about them because they require relatively much maintenance and braking power or modulation is not that much better tbh.

[TobinHatesYou]

Did you take out your pads for a quick look? They might have been wearing off in an angle, or just glazed a bit so rough them up with some sandpaper.

There's 10+ things that could be wrong though. Like you said, all the ingredients (except for rain maybe) for accelerated wear are there. I've switched to disc brakes last year and unsure if I'm that happy about them because they require relatively much maintenance and braking power or modulation is not that much better tbh.

Though had he been on rim-brake carbon clinchers in this situation, then his rims probably would have delaminated, leaving alloy rims as the only suitable choice. And even then if he’d been running a latex tube, that might have exploded as well. And that terrible burning rubber smell…

—

My suggestion would be to use aero drag as much as possible and to let yourself build up speed before aggressive late braking. Do everything can to avoid dragging the brakes. Timid descending will test any brake equipment. If you catch a car, either pass them or pull over and wait.

[OtterSpace]

While on vacation time is money and has a huge opportunity cost.

I'd go to a bike store and buy a non weight weenie front rotor, and likely a back rotor too, and a new set of pads.

Think about it more when you are back from vacation, inspect the take off parts then, and only then decide what parts live on the bike long term.

At a high level those rotors looks too anemic and are likely not sufficient for that kind of riding so you likely cooked them and glazed or wore out your pads. Rotors like that are fine for fairly flat or flowing hills but not super steep or other braking limited riding.

[nickf]

Those rotors like like Ashima rotors, are very similar in design. They are absolute garbage for descents, and overheat quickly. Ask me how I know. I have since switched to Galfer Road Wave rotors and they are MUCH better at managing heat on my gravel bike. Also semi-metallic pads will perform better in those situations better than organic pads which will glaze quickly.

[spdntrxi]

Galfers fade on me, but managable

[EtoDemerzel]

I did a steep descent (1100m at 13% with pinches up to 29%) yesterday, where you couldn't go faster than 20-30kp/h, so I had to drag my brakes constantly. At some point my brakes started "stuttering" and giving out almost completely.
I weigh 82kg and it was 35°C, so ideal conditions to overheat my brakes.

Today I descendet a smaller hill and the brakes felt weak, almost as if the pads are comletely worn, and they squeelt like crazy, which they have never done before.

I run Rival AXS with two 160mm Quaxar Lynx rotors and the stock organic pads. I last bled the bike a few months ago, so that shouldn't be a problem. I don't have a caliper with me, but the rotors shouldn't be worn already, they are just over 4000km old.

Do you guys know if this setup is safe to run for the rest of my vacation, or if not which part should be replaced?

You should rebleed the brakes. The fluid probably boiled and the fluid is aerated or has bubbles. Either you left some air in there or they absorbed some water.

Get new pads or sand down your current pads if they are still good. Clean the rotors if they are glazed.

[Torbjorn]

Out of curiosity, what climb was it that you did which has 1100 meter elevation gain and an average gradient of 13%?

[Pew]

^ +1 on this. Dot fluid absorbs water over time which will lead to boiling the brakes on hard descents. Nothing abnormal but good to know.

[BenCousins]

Out of curiosity, what climb was it that you did which has 1100 meter elevation gain and an average gradient of 13%?

I think he said 1100m length

[waswerte]

Out of curiosity, what climb was it that you did which has 1100 meter elevation gain and an average gradient of 13%?

Those numbers are from my mate, I just looked it up and it's 1300 meters over 12km. The mountain is called Cima delle Tre Croci. We also did about a km of the gravel after the road ends, but even 32mm road tires are not made for that. The worst part was that the roads were full of debree with bad surfaces, so you had to go super slow.

[waswerte]

Those rotors like like Ashima rotors, are very similar in design. They are absolute garbage for descents, and overheat quickly. Ask me how I know. I have since switched to Galfer Road Wave rotors and they are MUCH better at managing heat on my gravel bike. Also semi-metallic pads will perform better in those situations better than organic pads which will glaze quickly.

Before yesterday I've honestly never had any issues, and I have done some big descents with bikepacking gear. I think the difference was that I never had to drag them for this long. Yesterday I was never not on the brakes.

[waswerte]

You should rebleed the brakes. The fluid probably boiled and the fluid is aerated or has bubbles. Either you left some air in there or they absorbed some water.

Get new pads or sand down your current pads if they are still good. Clean the rotors if they are glazed.
[/quote]

I'll try to sand them down and clean the rotor, all the bike shops are closed here tomorrow. If that doesn't work I'll just get fresh pads and a set of heavy rotors. Honestly I think at my weight I'll just stick to heavy rotors from now on.

[MikeD]

Definately those rotors are bad for dissapating heat. Go with the OEM rotors or at least better ones with more surface area/ less cutaways. Your pads are cooked. Don't even bother sanding them. Replace them, preferably with semi-metallic or metallic pads. Resin pads are at the low end for temperature resistance. If your brake lever(s) didn't go to the bar, you didn't boil the fluid. Sometimes, you should just pull over and let the brakes cool.

[Aeo]

If you regularly ride like this, switch to SwissStop Disc E or Exotherm pads:
https://www.swissstop.com/brakepads/dis ... c35/disce/
https://www.swissstop.com/brakepads/dis ... exotherm2/

The next step is using a 180mm brake rotor, you will need an adapter like this:
https://peak-torque.com/products/180mm- ... avel-bikes

Ideally, check with the frame/fork manufacturer if you are allowed to run a 180mm rotor.