So I have my three bikes hung up in the garage. All with different brake pad vendors/compounds. All three running different Shimano models of brakes. And, after being unused for a week or two all of them end up squealing when finally used.

I know I should get them out and ride more frequently, and it’s probably the sound of them crying at their lack of use – but two young children prevent me getting out as much as I’d like.

This problem has been going on for a while, and more often than not I end up removing the pads, heating them in the oven, then cleaning with isopropyl etc etc. Which works as a short term solution. But I then take it out on a ride, hang it up when done, and then when I come back to it the noise has returned.

The only thing I think it can be is our tumble dryer (condensing, not vented) also lives in the garage, and the humidity is somehow affecting the pads? Could this be it?

after being unused for a week or two all of them end up squealing when finally used.

My guess would be the rotors getting contaminated with dust and lint from the dryer. A few hard stops will bed the pads and rotors in again and stop the squealing. Not worth worrying about IMO.

It may be, but sadly a few hard stops doesn’t cure it – the squealing lasts pretty much until I go through the process of cleaning them. Initially there is some power loss, which eventually comes back, but the noise remains.

Pads I’m using are Uber Race Matrix, Shimano G02S Resins, and Uber Semi-Metallic.

…two young children…

Contaminated disks 😀

My guesswould be you have the shimano calliper seals with the tiny leak contaminating the pads. A bit odd all 3 would go at once tho

It’s probably not the pads getting contaminated, it’s the disks. Have you tried just wiping the disks with alcohol and a clean cloth before you ride, but not cleaning the pads?

SHimano brake seals leak if they are not used very often. It’s just what they do.
If theyre under 2 years old, send ’em back, you’ll get new ones.

Are you transporting the bikes on the outside of a car? Road crud always seemed to be my biggest cause of brake noise.

I don’t think it’s leaking seals. None of them show any indication they’re leaking when removing/replacing pads.

Also, bikes are transported inside the car.

You often can’t see the Shimano leaks – they’re tiny. You could try taking the lads out, put tissue behind them and put them back in a leave overnight and see f that highlights and minor leakage.

Other than that you could keep a bike in the house for a couple of weeks and see if that makes any difference – i.e. away from the dryer.

Either way completely clean off your rotors with brake cleaner and drop a new set of pads into one of the bikes. Then bed the brake pads in properly and see if you still have squeaks. If you haven’t, then something is contaminating your brakes whilst hung up.

I had a mystery leak from the hose to calliper connection – only noticed it when it beaded up after leaving for a while, it disdn’t seem to have crept down but it obviously had.. Shortened the host slightly and new olive fixed it.

Either way completely clean off your rotors with brake cleaner and drop a new set of pads into one of the bikes. Then bed the brake pads in properly and see if you still have squeaks. If you haven’t, then something is contaminating your brakes whilst hung up.

That’s exactly what I did with the last set of pads – once again they howled the next time I took them out. I could understand if it was one pair of the brake doing it. But it’s on all three bikes.

I rebedded my old pads in – dragged down a big hill and then squirted my water bottle over them. The squeal disappeared in a puff of steam. Hasn’t returned for over a week but I still tense every time I pull the brakes (on my third replacement caliper).

It’s a design problem IMO.

We can stop it temporarily, by cleaning etc, but there’s an underlying cause. All our efforts are only palliative.

The noise suggests there’s resonance going on somewhere.

Find the part that’s resonating and alter its frequency by changing its design.

I don’t think it’s leaking seals. None of them show any indication they’re leaking when removing/replacing pads.

The quantity of oil leaking from Shimano disks will be very small. You’ll not notice it other than the noisey squeak. NOt evry brake does it, but of my 7 bikes, only the 4pot saint brakes and the XTR calipers have never done it. XT, SLX and Zee all do it eventually.

I just send them back and buy another set. They’ve (CRC) always replaced them in the end. So, i reckon i get 3-4 years from one set, then they go in the bin.

I’ll chip in here, rather than start a new thread. About a week ago I swapped out the aluminium/carbon fork on my Swift for a set of steel Swift forks; since doing this I’ve been getting occasional, but loud, Banshee like howl from the front brake. The pads were pretty worn so I replaced them which temporarily solved the problem (I’ve also cleaned the rotor); now however I get loud howling from the front brake at the bottom of hills (heat related?) which stops after a few applications of the brake; previously I’d only get a similar howl in the wet.

I did wonder about leaky seals as the brakes (SLX) are quite a few years old but this doesn’t feel right – there’s no sign of oil on the pads which are dry as expected and pumping the brake lever hard doesn’t result in howling.

I did wonder about resonance but wouldn’t have a clue how to sort this out. Previously the calliper was mounted post mount via a post mount-post mount 180mm adapter but is now mounted to an IS mount via an IS-post mount adapter for 180mm rotors (probably not relevant).

The rotor (SRAM Centerline) is running true and is fairly new with no performance problems. I did wonder whether there might be a bit of rotor wear and that perhaps the different mounts & adapters were positioning the pads ever so slightly differently.

You sure it’s not just because you’ve cleaned the bikes with muc off and then have used them since. Mine always do it

Another one who reckons its the Shimano calipers leaking

Had it on my Zee’s and XT’s so sent them back to CRC who couldnt see any leak so forwarded them onto Shimano’s Uk distro who did a test and hey presto they confirmed that they were leaking ever so slightly

They replaced them under warranty, i then sold them straight away and bought Hope’s and never looked back

PJay

…I did wonder about resonance but wouldn’t have a clue how to sort this out…

Nor do I – although I have a few theories.

It’s the disk – unlikely because it would be more prominent on some models than others. Every disk brake I’ve had sings at some stage despite different makes and diameters.

It’s the brake pads – I suspect that dirt/contaminants on the disk result in a grab and release scenario happening at high frequency. So fundamentally the brake pads may be acting in a similar manner to the reed in a set of bagpipes but less melodiously.

I have thought of trying a dab of silicon or similar on the back of the brake pads, but it would have to be something capable of handling high temperatures – any suggestions as to what would do the job? Sugru? Gasket goo?

copaslip is used on the back of pads on cars and motorbikes

I get squealing under two conditions – road use in winter so that is clearly contamination and the other is on the tandem from “cold polishing” which is when you use the brakes a lot but gently so the pads never get up to temperature resulting in a glazed surface ( but this is not the same as glazing which is a high temp effect)