fmcco

Hi all, for the past 12 months plus the disc brakes (Shimano, hydraulic) on my 2018 Cube SL Road have been screeching. They are loud enough to wake the dead and embarrassing the hell out of me. So far I have tried:
- full brake service at LBS, rotors cleaned - no difference
- new BBB pads fitted by LBS - no difference
- sanded and cleaned pads & rotors - no difference
- sanded and cleaned again, recentred rotor, cones tightened by LBS - no difference
- fitted new rotor & pads, both Shimano, on back, bedded in carefully. This worked until it rained, then screeching like mad again, even when dry.
- sanded and cleaned the new rotor and pads, bedded in again. Again all good until it rained, then back to square one.

So while sanding/cleaning/bedding in after rain works, it is not really a solution - where I live you're lucky to get 3 dry days in a row. What else can I try? The only thing that hasn't been replaced is the hydraulic caliper itself, which seems an extreme solution given that it is not even in contact with the rotor. I'm at the stage now where I'm avoiding using the bike due to the commotion involved in stopping the thing. Thanks for any help that can be offered!

Iride01 

Maybe you are fussing too much with them. Leave them alone and maybe it will go away.

If you aren't careful to keep cleaners and spray products away from the discs and pads, then you may be in a hopeless situation.

I don't see that you've mentioned you cleaned the pads and discs with alcohol. If not you might want to try that. But don't expect immediate results if the pads have soaked up oily contaminates.

I had squealing, squally rim brakes on a bike that took months to fix themselves. Note the key point there is that I let them fix themselves.

Barry2 

When troubleshooting the easiest method is substitution.
if you trade wheels & Rotors with a buddy, does the squeal follow the wheel or bike?
For ease, just try the front wheel first.

Only bad point being you might have to replace your buddies front rotor and pads if you contaminate them.
If you do have to replace, do both rotor and pad at the same time!

Barry

fmcco

Thanks, my initial approach was leave them alone and hope they came good, but they never did. Alcohol (IPA) is all that I have been using to clean them. I will try a more thorough clean of the whole area in case there is crap running into/onto them from elsewhere too.

Barry2 

Just checking... are you are using the correct alcohol (IPA) ?

fmcco

I always use triple-hopped IPA to clean the bike - what else would i use??

Yes, it is isopropyl alcohol I'm using.

Cyclist0108

If you are using metallic pads, switch to organic pads (or vice versa). In general, organic pads are quieter, but metallic pads are slightly better under wet conditions.

blamester

Looks like you have tried everything.
It seems to be common enough.
You might try to loosen the bolts on the disc pull the brake as hard as you can and tighten them up good again as you hold the brake.
I'm not saying this will work but it might help you never know. Same with the caliper if that doesn't work. I would even pull on the top of the wheel as you tighten the bolts. Leave no stone unturned. You will probably need help.
But really it could be down to the fork or the wheel. You have clearly been meticulous in replacing and cleaning parts so what else is there.
Check out the 2019 brussells classic road race. Wait till you hear that screeching. And they are the professionals.

dgately

I had a similar problem with Shimano hydraulic discs. I went through the same steps as you many times. Cleaning the pads and rotors with alcohol, sanding them slightly with 200 grit sandpaper, etc... The brakes would eventually start howling after a short ride. Examining the brake while applying them on the stand revealed that one of the caliper pistons was not activating as much as the one on the opposite side of the rotor. So, as the 'good' piston pressed up against the rotor, it actually was forcing the rotor towards the other piston, causing lots of pressure and the squeal. I replaced the entire caliper and now have quiet brakes.

Nyah

Fmcco, would I be incorrect in guessing that your frame/fork uses QR-skewers?

dgately

2018 Cube with disc brakes... I assume thru axles, no?

Moisture

Sorry man but I just wouldn't invest this much effort and get stressed over my brakes like this unless they aren't working well.

If it annoys you this much, maybe just get a bike without disc brakes.

Nyah

QR-skewers confirmed. Example 1, example 2.

Thru-axles were developed to prevent this problem. I'm sorry to say that getting a whole new frame/fork is the solution, but it is.

Lazyass

Sanding my rotors was what finally got them quiet. If I had been like you and that didn't work I was going to sell the bike and never look at discs again. I still don't really like them.

fmcco

Thanks for all the replies. My last bike also had QR skewers and (cheaper Tektro) disc brakes, and while there was a bit of noise from the brakes it was acceptable and didn't scare small children 50m away etc. so I'm struggling to see how there could be no solution to this bar effectively changing the bike. I might see if I can swap a caliper somewhere as that's all there is left.

GamblerGORD53

Maybe it's because of the frame and small rotors.
I have a cable TRP Spyre with my 203 mm Rohloff disc, with resin pads. I have since bought but not used the BBB BB5 resin pads.
It was installed during my last tour, with my DIY setup. 4,500 miles I think, ZERO squeaks. Only rained on a couple times. I have long pull SA levers. Probably why mine never squeaks, is it can lock tight instantly. I spent no time cleaning anything.
I maybe pull a clean rag thru to dust it off when the wheel is off. The disc was on the hub for 1,600 miles without the caliper installed. So it certainly got wet a few times.
My bike is heavy steel, at 75 to 120 lbs. LOL.

I have 2 SA XL FDD dyno drum brake front hubs. The first one has 26,000 miles with NO squeaks either.

jgwilliams

I don't think that's the reason that thru-axles were developed, although it may be a benefit.

On cars putting copper grease between the pads and the pistons used to help. I wonder if that would also help with bikes? It depends whether the squeal is from the pad vibrating against the rotor or against the piston, but if it's the latter then some grease ought to help.

DorkDisk

Since you tried everything, and pad / rotor type mismatch would be my first guess, maybe its fluid resonance? Its a long shot, mostly used on old Avids and for turkey warbling but its easy enough to try. Tie a zip tie to the hose and frame/fork near the caliper and see if that helps.

Cyclist0108

A slightly less expensive alternative that works almost as well:




This essentially works the same way, and you can really crank down much more effectively than with standard quick release levers.

canopus 

For cars we use a product for disc brake squeal to prevent the pad from vibrating against the caliper/piston. DO NOT USE GREASE for this. If grease gets on the pad it is not good. It is a liquid plastic/rubbery compound that will dry. I use it on the back of the pads at the contact points with the caliper and piston. Put a small amount on the back of the pad, let it dry for 15 minutes the put it all back together.
I would recommend trying that before replacing a fork or frame and using grease and doing any more cleaning.

Cleaning pads/rotors will not reduce break squeal.

djb

as someone who has had screeching discs, i get the frustration, but its hard for online folks to know what you're doing. You could be contaminating stuff--oh, when you changed rotors and pads, was this done for free by a shop?
If you did it, there could be something in wht you did, who knows.

you say, "bedding" them in, but what did you do? how specifically I mean?

the time I had this really bad with my front rotor, I tried all kinds of stuff, and finally sanding lightly the rotor helped, but oddly enough, I find its easier to just leave things be cleaning wise, and it usually goes away.
but yes, humidity seems always to create more squeals, even with rim brakes.

etherhuffer 

Just ride with my wife, that brake noise will seem minimal in no time

canopus 

Errr... I take it she doesn't frequent this site then...

etherhuffer 

Nope!
I have some really goid suggestions on noise cancelling headphones too!

canopus 

Because I answer myself, I gave those to her so she couldn't hear me...