Why have my brakes started to squeel?

It’s annoying and a bit embarrassing! Road bike all Shimano ultegra kit. Bike is a few years old and nothing has changed setup wise.

It started a couple of days ago coming down the Iseran and now it won’t stop. Seems only to happen when braking hard for hairpins. A little dab to scrub and it is fine.  My style of riding hasn’t changed, this bikes done some big mountains over the last few years.

Both brakes. Changed the rear pads and it made no difference.

Bit worried that it goes away briefly with a squirt of water. That’s normally a symptom of leaky calipers. But it doesn’t occur at low speeds.

I’ve only got one more day and they do stop me.

Rotors look a little worn and discoloured. But nothing that I would give a second glance if I hadn’t been trying to figure the problem.

Rotors/calipers are expensive so I’d like to try and pick the right one.

Any other ideas?

Possibly glazed pads if you have been doing a lot of hard braking?  Sand the pads is the cure if so.

Changed pads as I thought that. Uberbike Sintered. Were fine last time I was in the Alps on some of the same mountains.

I have the same.   Cleaned the rotors with IPA and added new pads, always squeals at the end of the braking distance when coming to a halt.

Few years on a shimano road caliper is great tbh. Bin and replace on return.

Yes leaning on that. All seems to be RRP though.

Probably trying to express their dismay at your spelling ?

Why have my brakes started to squeel?

Said thomas to the naughty trucks

I had some SRAM Rival brakes that would squeal constantly, I changed pads and rotors several times before finally taking the whole lot off and sending to SRAM under warranty, they replaced the pads and rotors but said the brakes were fine. I disagree.

While they were away at SRAM I fitted some Red callipers and levers which have not been a problem thus far (2000 miles UK road/gravel) .

Yours probably need binning as well.

I had a squealing brake for ages, changed pads and rotor then finally had to admit it was probably a slightly leaking calliper. Changed the calliper and it stopped. Didn’t bother bleeding the system or changing the olive, just disconnected it, held the cable up the jammed it back into the new one. Worked fine.

If not lacking power, then not likely a leak. My front GRX squealed on a ride after intending to improve clearance between pads and rotor. Re-centred it more successfully after the ride and the squeal went away.

I’ve not had a leaky caliper in years. MTB master cylinders on levers yes, but no calipers.

I had a really bad squeal on a mechanical caliper for ages. I tried new pads, greasing the backs, messing around with the retainer, aligning the caliper, basically everything I could think of, over and over. In the end I stripped it all down, made sure the caliper bolts were properly greased, put it back together and it mostly went away. I still don’t know what the cause was but I put it down to ‘dry’ joints on a bike that had seen more than enough wet weather over the years, potentially creating some kind of resonance. I honestly don’t know. It drove me nuts for the best part of a year.

Do you need an olive at the calliper? Didn’t think you did? Last time I had this issue it was a cheap front brake on my commuter so bought the whole lot.

The fact there isn’t a noticeable loss in power does go against a leaky calliper. But there wouldn’t be an alignment issue that suddenly appeared half way through a ride. I could see a leak getting worse as the system heated up and things expanded and then contracted.

I’ve sorted of convinced myself now.

Caliper end of the hose needs an olive yes – you must have one fitted, otherwise there’d be nothing holding the hose in place.

Sorry, just realised I changed the calliper with new hose attached, I had a whole spare set and just discarded the new lever because it didn’t fit. Still convinced it was a slowly leaking calliper though.

Watching this with interest. My rear brake is making a norrible noise. I’ve cleaned the rotor repeatedly, sanded the pads, replaced them when it didn’t work, but to no avail. The new pads seemed to be bedded in OK but after about 15 minutes they were just as bad as the old ones.