Squeaky protesting brakes

DS

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Just wondering if anyone has experienced this.
After 15 - 20 minutes of continuous use of brakes on tight fast-ish descending roads the front brakes begin to protest (i.e. squeak/squeal).
I’ve experienced this on my own bike in June whilst on a tour of the Picos & Pyrenees.
And I’m now experiencing this on a hire bike here in the Spanish Pyrenees and mountains of Catalonia.
Both bikes 2021 GSA’s. Pads seem fine. Discs look good.
Only happens on tight twistiest where there’s no let up (straights) for a few kilometres.
Had my own brakes checked over by Barnstormers and they said they were fine.
So, is this a case of ‘they all do this’ or is it overheating ?
Never experienced this in the UK because there simply aren’t roads like these for the distances I’m referring to.
 

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Hi DS
I have had the same in the UK but far more pronounced over the last couple of months when the same GSA was in Spain. We had some very high temperatures this summer and whether I was more alert to it or maybe riding with the visor open all day I did notice it more. I agree the twisty roads with more use of the brakes seemed to make it more noticeable.
 
Here in Portugal and high temperatures, my 2021 GS has squeeky brakes in summer. I treated the rear part of the pads with copper grease and the problem was solved for good. You just have to know how to apply it.
 
Here in Portugal and high temperatures, my 2021 GS has squeeky brakes in summer. I treated the rear part of the pads with copper grease and the problem was solved for good. You just have to know how to apply it.

Interesting. Might have to look into this when we ride out here next spring. Or different pads?
It was 27’c here today and they were protesting loudly at times on the descents.
They squealed less when 1] I rid less spiritedly and 2] I applied far more rear on the descents than I normally would.
So I’m pretty sure it’s the fronts that are protesting under load, but only on the descents.
Also interestingly the hire bike is on Brembos and my bike has the Haynes; no noticeable difference in performance.
The mountain roads around here are insanely wonderful; beats the Picos hands down.
 
Brakes

I should point out there’s no noticeable difference in performance squeal or no squeal.
 

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I had this on my disc braked mountain bike. Took it to a bike shop and was told it was down to the discs and pads glazing due to prolonged use on downhill roads. A rub over with some fine emery cloth of both disc and pads solved it.
 
I have this with mine at very pedestrian speeds, notably after going over speed bumps. Mine squeak and squeal without the brakes being applied though, just riding along at a constant speed and the garage rubbed down the pads a bit but it didn't solve the issue so I'm not sure what the cause is as it doesn't happen all the time.
 
The squeal is consequence of very tiny, high frequency vibration of the pads on the disk. The solution of copper grease I mentioned above always solved it on all the bikes I owned in last 40 years.
However, one mechanic told me there was the other solution that he uses every time on every bike when he installs new pads. I don't know if it works but he says it does. He told me the vibration starts on the edge of the pad. The edge is sharp so the pad starts "jumping" when you apply the brake. His solution is with angle grinder. Each end of the pad is with 90º angle of the pad material, like this |___________|. What he does is he grinds the edges to 45º, like this \______________/. He says it works. I haven't tried it yet.
The edges he was talking about are not on the sides of the pad's material, but on each end.
 
I bevel the leading and trailing edges of pads and apply plastilube to the rear of the backplates. No noise.
 
I always copper grease the rear of the pad before application.
Never havea problem with bikes or cars in all situations
 
I had a squeaky brake issue on my G/S with HE big disc conversion. With sintered HH pads it squealed as i released the lever and with softer, organic pads it never did. I was well aware of the practice of putting copper slip on the back of the pad and have had success doing this in the past, but it made no difference in this case.

The HH pads were noticeably better for stopping power, so I just put up with it, possibly adapting my braking pressure to minimise the problem. Only really did it as I released the brake. Never tried chamfering the pad material. That sounds like a good idea to try IMO.

I've found genuine BMW pads to be best on my old GSAs. I put an EBC axle set on the front of my twin cam once and it just felt wrong from the off. Bought a genuine set and all was right again (except my bank balance - Not cheap).
 


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