Sqeaking brakes

[mike killay]

I am getting fed up with adjusting my Avid BB7 disc brakes.
I set them just right, but within a few miles they are squeaking.
Seriously thinking of fitting rim brakes.

 

[soundwave]

get some decent rotors and sinterd brake pads.

https://www.chainreactioncycles.com/hope-floating-disc-brake-rotor/rp-prod145730https://www.chainreactioncycles.com/hope-floating-disc-brake-rotor/rp-prod145730

 

[Nealh]

Pad material ?
I use the basic Shimano BR445/6 caliper with BS01 pads, resin or semi metallic and have no issues. The pads I use are cheap China knock offs for about £1 - £2 a pair.
May be you are using wrong pad material for the discs or just crappy discs.

 

[Nextlife1]

Dealt with this problem for ages until I switched to DT Swiss pads and rotors. Problem solved.

 

[Deleted member 25121]

Are your discs true? It might be worth investing in a truing tool such as:

Get Your Wiggle On | Cycle, Run & Outdoor Shop | Wiggle

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[Andy-Mat]

I am getting fed up with adjusting my Avid BB7 disc brakes.
I set them just right, but within a few miles they are squeaking.
Seriously thinking of fitting rim brakes.

It may be possible that even from new, the disks themselves are reversed.
Many people just put them on the bike as they have been assembled, but the assemblers are probably some of the worst paid people in the far east, they simply don't care, nor are they trained properly, as the job (should be) so simple!
An Engineer will see the error (if there is one) immediately....
Send me a photo that clearly shows the disks relative to the front wheel and the back wheel please. Take the pictures from the Left hand side only.
The front one is very easy to fix and test, and costs only a bit of time to reverse.
Leave the rear one till later assuming I see a problem with both, its a bit more work.
I assume that both squeak, you did not say.
Also, once they start squeaking, even if then properly adjusted and set, the squeak may still happen till the rotors are replaced.....happy days!
regards
Andy

 

[mike killay]

Well, I have some spare rotors so I will try fitting them. The existing ones are true and on the correct way, the wheel bearings do not have any play, so it's down to either the pads or rotors, but I am fed up and this is positively (Basil Fawlty) their last chance!

 

[Andy-Mat]

Well, I have some spare rotors so I will try fitting them. The existing ones are true and on the correct way, the wheel bearings do not have any play, so it's down to either the pads or rotors, but I am fed up and this is positively (Basil Fawlty) their last chance!

How do you know they are mounted correctly?
IMHO, at least 50% are mounted wrongly, as you have a 50% chance of getting it right.
The threaded part in the middle, the "Boss" I believe its called, can usually only be mounted one way in my experience, but the disk itself can be mounted one of two ways on that Boss.
A photo would really help to make a better diagnosis.....
But entirely your choice either way of course.....
But I personally would never ever go back to rim brakes, after having my first bike with disks!
Rim brakes can also be loud too!!
Again, your choice!
Some disks can be mounted safely both ways, due to the way they are designed and made.
Also, slightly thicker disks are less likely to get noisy, even if mounted wrongly, more stable....maybe a better choice? They are of course a few grams heavier, but no worse than small change in your pocket!
Light weight parts are not always the best!!
regards
Andy

 

[mike killay]

I know that they are mounted correctly because they have a direction arrow on them.
Anyway, I have changed the front disc and will give it a test.
Rim brakes have improved immensely since the 1950s when we had to put up with the dire 'Fibrax' blocks.

 

[Andy-Mat]

I know that they are mounted correctly because they have a direction arrow on them.
Anyway, I have changed the front disc and will give it a test.
Rim brakes have improved immensely since the 1950s when we had to put up with the dire 'Fibrax' blocks.

I have seen that wrongly made too. The Chinese workers make many mistakes!
Please make me a quick photo, as I can tell from the way the holes are aligned, and it might help you further.
Andy

 

[mike killay]

The squeaking has stopped with the new rotor.

 

[awol]

I have seen that wrongly made too. The Chinese workers make many mistakes!
Please make me a quick photo, as I can tell from the way the holes are aligned, and it might help you further.
Andy

It would be interesting to see an example of a correct and an incorrect fitted rotor if you have access to any, also explaining the reasons as I have always just gone off the arrows too.

 

[Andy-Mat]

The squeaking has stopped with the new rotor.

I am pleased for you......
Andy

 

[KirstinS]

I have decent shimano discs and hydro brakes

And I still find that variable ride conditions and breaks between rides can cause this on an intermittent basis

 

[Andy-Mat]

I have devised a small test for any of you interested, as to how and why so many bike brake disks are incorrectly orientated for optimum and correct usage. Possibly to cause vibration and squealing when used.
Further more, though I have not tested this out (HOW?), but common sense tells me that a squealing brake probably does not stop as well as a quiet(er) one of the same type etc. does, under emergency situations!
And as the vibration will most likely affect the contact area negatively and further extra heating will be possible!
Remember the rule of physics that braking is independent of contact area, provided one ignores the heating effects.
regards
Andy
PS.The force due to friction is generally independent of the contact area between the two surfaces. This means that even if you have two heavy objects of the same mass, where one is half as long and twice as high as the other one, they still experience the same frictional force when you drag them over the ground.

How Surface Area Affects the Force of Friction - dummies

The force of friction comes from the surface characteristics of materials that come into contact. How does physics predict those characteristics theoretically?

www.dummies.com

 

[Andy-Mat]

The squeaking has stopped with the new rotor.

Try my little disk brake quiz!
Let us see how you get on!!
regards
Andy

 

[awol]

I have devised a small test for any of you interested, as to how and why so many bike brake disks are incorrectly orientated for optimum and correct usage. Possibly to cause vibration and squealing when used.
Further more, though I have not tested this out (HOW?), but common sense tells me that a squealing brake probably does not stop as well as a quiet(er) one of the same type etc. does, under emergency situations!
And as the vibration will most likely affect the contact area negatively and further extra heating will be possible!
Remember the rule of physics that braking is independent of contact area, provided one ignores the heating effects.
regards
Andy
PS.The force due to friction is generally independent of the contact area between the two surfaces. This means that even if you have two heavy objects of the same mass, where one is half as long and twice as high as the other one, they still experience the same frictional force when you drag them over the ground.

How Surface Area Affects the Force of Friction - dummies

The force of friction comes from the surface characteristics of materials that come into contact. How does physics predict those characteristics theoretically?

www.dummies.com

I will go off how mine are on my bike and hope they are correct.
1-C, 2-C, 3-C, 4-C, 5-W , 6-C, 7-I, 8-C, 9-C, 10-W

 

[Andy-Mat]

I will go off how mine are on my bike and hope they are correct.
1-C, 2-C, 3-C, 4-C, 5-W , 6-C, 7-I, 8-C, 9-C, 10-W

Many thanks for trying your luck, but many wrong answers, sadly!
Many possibilities for brake squeal!
I will not say how many were right and wrong at this time as it might assist others here to get more right, unfairly.
But you have kindly proven (and you are definitely NOT ALONE!) that generally speaking few people understand how a Push- or e-bike brake disk needs to be set up and used.
Please do not be in anyway disheartened, as you were the first and therefore the only one brave enough to "break the ice", but it may cause any others simply to retreat into their shells!!
I had expected/hoped more people would try and get the quiz correct.....and want to learn something new too.
Many thanks for your attempt, but I will give it a few more days before I post the answers and the full explanation.
You should not forget that the problems start with the manufacturers, and continues through the industry and the customers.....nobody should blame themselves.
It is not surprising to me personally, that so many people simply do not understand the basic principles....
It is actually a quiz that possibly only a good engineer will get fully correct and know exactly why!
regards
Andy

 

[esuark]

hi new here looked at this and I come to exactly the same conclusion as awol. so I must be working on the same theory as awol .

 

[Andy-Mat]

hi new here looked at this and I come to exactly the same conclusion as awol. so I must be working on the same theory as awol .

I have mentioned this problem to other bikers here in Germany, almost none of them believe or understand it either.
Its not just the UK!!
Wait up a few days and I will explain all, in a way that I hope everyone will fully understand.
regards
Andy