I’ve had squealing issues with some Shimano rotors, irrespective of pads and bedding-in. Not all but some.

In the end I ditched said squealer and used a centreline rotor instead, with Rahox pads.

I wondered about rotor choice, my stock centreline rotors were dreadful so I tried some Magura Storm SL with aggressive cutouts, in the hope that this would break up the film of water between pads and rotor, but no real effect.

Went back to stock Deore on the back and TRP on the front, neither was great but they were old rotors so potentially hadn’t been bedded in properly etc. I tried taking them back to their original finish with some wet and dry pads on a mechanical sander, but not sure how much effect it had. Either way they squealed as soon as they got wet (and that was with new pads that had barely seen any use on wet roads, in fact probably none, so I don’t buy the contamination thing).

Now got XT 6-bolt. Am hoping that the central aluminium carrier is somehow stiffer and might prevent the resonance that amplifies/causes the squealing, but I’m not hopeful, was riding with someone the other day with some posh Dura Ace rotors of similar construction and they made a right racket the second he got some water on them (even puddle splashes etc). They were fine in the dry though.

I think it’s just pot-luck until you find a combination of components that doesn’t create the magic frequency that causes the squeal, but it’s an expensive game to play trying to find them!

Wonder if the Hope callipers have some sort of toe-in effect due to the 4 pistons? Sure I’d heard reports of them being just as noisy…

My commuter with bb7s, alligator pads that have thosands of miles on them and never get warmed up properly and has months of road contamination at any one time are fine. My Shimano road brakes (the not marked ultegra, but better than 105) squeal appallingly on the front. Until I fit fresh pads and rotors. They are quiet for a single ride and then the banshees come back.

I have a couple of bikes with Ultegra discs.

The first I’ve had from new and was fine until I swapped the pads for sintered, finned versions. They were fine in the dry, but like carrying around a klaxon when riding in the wet. And they never stopped, even after 50 miles of HOOONK HOOOONK. Returned home, and binned the (very!) expensive pads and replaced with organic ones. No problems since then.

I recently bought a used road bike with the same brakes. This one hadn’t been used for a few months prior to me buying it and, once again, the brakes were very noisy, but this time in all conditions. I tried a few things (cleaning rotors, sanding pads), but in the end, swapped the pads (oddly, for the sintered ones from the gravel bike) and not had a problem since. They’ll probably be awful in the wet, but this bike is mostly used for dry rides, so it won’t be an issue. I’ve since replaced the rotors too for some new “freeza” ones, and they’ve stayed quiet.

Like many here, I’ve run MTB discs for 20 years and never found them as much grief as my much more limited experience with road discs, which seem to be a bit of a black art…

Same brakes as OP here. I wear headphones when commuting, so the squealing doesn’t bother me that much 🙂 To go back to rim brakes is bloody madness!
They only squeal in the wet, and it’s due to contamination, as mentioned previously. They still stop brilliantly, so it’s really not worth worrying about, I believe.
Mine were, at one stage, squealing when dry too – I had a tip from my LBS – spray liberally with brake cleaner then burn it off. Cleans all the contaminants off in one hit, so stops the squealing for a good while.
(remove wheel, lie it flat and be careful 😀 )

I thought the standard way of stopping brakes squealing on mtbs anyway ways to put some copperslip on the back of the pad. Do not blame me though if it destroys your brakes.

I rode my rim braked bike yesterday in the rain and had forgotten just how bad they are compared to a functioning disc brake. However, I won’t put up with the squealing disc brakes so have ordered some Hope RX4 disc brakes in the hope that this will fix the issue. The point of disc brakes was to provide an increased level of confidence when braking in wet condition and given I’d rather not pull the lever than listen to the horrendous squealing kind of defeats the object. If people are happy to put up with that level of noise then great, but AFAIC these brakes aren’t fit for purpose.

To go back to rim brakes is bloody madness!

Any more mad than having to wear headphones to drown out the noise of your squealy brakes because you’ve neglected to routinely set fire to them? 😉

(note since smileys never work for me anymore, please take that comment in jest…)

My headphone wearing goes back to riding to work on a caliper braked mountain bike (SQUEEEEAL!) with slicks I’ll have you know! 😀

Look on the positive side – at least people hear you coming..!

Sorry, not sure whether it’s a good idea to revive this thread or not! I’ve been having issues on the ‘cross bike and it’s got practically the same setup as my road bike, which doesn’t squeal*, so I’m intrigued what other people’s experiences are. I’ve read tons about the subject and tried all sorts of things and there still seems to be no One Unifying Answer to solve brake squeal.

* there seem to be two types of squeal on the road bike: one happens very occasionally when it’s wet and I’m braking gently, for example approaching a junction. This stops if I brake hard. The other type happens at the end of a big descent when obviously everything has heated up a LOT and I’m braking hard. After the rotors have stopped ticking and the pad fins have done their job, the brakes don’t squeal. It might just be my imagination, but the latter noise seems more to be an indication of the brakes warning me they havnae got any more power, captain… like when Swissstop BXP rim brake pads squeal when you’re really pushing them.

The closest thing I’m seeing to consensus is the need to get the brakes hot occasionally to burn off contamination. This doesn’t entirely align with my experiences but it’s the only thing I haven’t deliberately tried.

Maybe you aren’t getting the brakes hot enough on the CX bike?

Greasing the back of the pads has been mentioned a couple of times. Copper slip and/or shims is fairly standard on car brake pads. Does is actually work on bikes? I guess the principle is the same, but there is a massive difference in scale.