Has anyone ever had rotors break because they are too thin?

I only use rim brakes, so I don’t face this issue.

....other than every time you brake when they are wet.

My hydraulic rim brakes on my tandem have no issues when wet. They have no issues going down a mountain pass and not functioning because of overheating. My touring bicycle has disk brakes and they do not live up to what they are hyped to be. On a motor vehicle the rotors are made thick enough to handle the heat. They are not made thick enough to handle the heat with a heavy laden touring bicycle coming down a windy mountain pass and having to slow down behind traffic.

My experience with bicycle disc brakes is minimal, but with solid rotor discs on cars or motorcycles, I have seen warping and cracking when they get too worn. As a bicycle disc is thinner and smaller, I would suspect the same would be possible.

To me, the brakes are that one piece of equipment that is frequently a very important factor in whether you are injured of killed if they do not work as intended. I make sure I know what the wear limits are and what the signs of needing to be serviced or replaced are for the brakes on my bicycles and my vehicles. I do not wait for them to fail or wear to the point of damaging the rotors (or rim). It is not a difficult measurement to take, especially since on a bicycle it is out in the clear and not behind a wheel. Being knowledgeable helps you know when to replace the pads or rotors, AND then to do it yourself or take it to the shop before it gets real expensive. It can also prevents surprises at the shop.

I have descended passes in the Rockies and elsewhere riding fully-loaded bikes in the rain (and snow) with no issues. Or maybe I am dead right now and just don't know it, like in that movie?

I just got these in last week for my commuter/tourer. Still sitting here in my office. I’ll probably have them installed soon.

My guess is a warping of the rotor, and the rotor not returning to position either as quickly or at all.

Interesting line of reasoning throughout that seems to come down to......

Did Not Die = No Issues.

Yes, I too used rim brakes in wet, steep mountainous terrain and wet crossings for years and lived to talk about it. I am overall fine with a rim brake bike (I own several and even occasionally trail ride on one), but these are brakes, not family members. I don't get all bothered when the downsides are pointed out. I am not about to kid myself about braking in the wet. The braking is much less predictable before the rim is clear of water. But like so many other things, you don't really notice some issues until they are gone.

Look, I was responding to an off-topic post that was utterly irrelevant to the thread topic. Someone had no useful advice or insight about the OPs question about disc brakes, so instead they virtue signal about not using them, hoping to have a rim vs disc debate. And I made the mistake of feeding the troll. My bad.

Which brakes, which rotors, and which pads are you using? The last two make a HUGE difference.

That's now what I wrote. I wrote that I have had no issues. I then asked whether I am dead, wondering if death by rim brake was an issue I encountered without knowing it. However, the two are not are not inextricably linked.

Yeah, I was really stretching on that one

Kool Stop Salmon are my go-to pads.

Still can't get them to fit in my disc calipers, though

Those are for bigger discs in the 559 to 622 mm range. You might need something for the 160 to 140 mm range

Paul Klamper Brakes: Kool Stop Avid Elixer SRAM MTB XX Sintered Metal Compound #KS-D296S pads. Hope 180mm front rotor. Magura Storm 203mm rotor rear. The front is the problem. It over heats. I just put a Magura ebike disk on the front and Kool Stop ceramic pads. I have to bed them in then I will see if there is improvement.

Funny, and often true.

Well, that is certainly a good setup. Thank you for not being one of those people complaining about their 140mm rotors overheating.

Interested to see how the new rotor works. Are these the 220mm ones? I would think they would handle the heat much better than the 180s.

I was going to suggest sintered pads, but you already tried those. I've never used ceramic. Interested to know how they work. I understand they work very well when hot, but don't last very long and chew up rotors.

I thought all situations are "did not die" situations up until one actually dies.

My Tandem came with the self energizing cantilever brakes. rain, shine or snow they worked well. Once they were wore out. They were no longer available for sale. I found some Magura hs66 brakes at Cambria 18 years ago. They were new old stock. I had tried other cantilevers and they sucked compared to the self energizing brakes. The Magura rim brakes were and still are the best brakes I have ever owned.

I can't go any larger than 180mm on the front rotor because the larger diameter rotor will sit against the fork blade. The new thicker 180mm rotor with the ceramic pads hasn't squalled and it is quieter then the sintered pads that I have on the rear. I had the wife drop me of up the hill a ways. This gives me over five miles with no stopes and one light that is easy to catch green. I did this several times. I coasted up to around 20mph and slowed down. I alternated between the front and sear brake. The front brake works better because I can actually use it now that it is not squalling.

I have seen some videos of the pros having locked up brakes. Mums is the word as to why this happened. There are some disk rotors that have an aluminum core with a thin outer metal braking surface. I have heard that the aluminum sometimes starts to melt. I believe some of these problems occurred because of under engineering. This isn't the industries first try at disk brakes for bicycles. I believe they can do better with the right motivation.