Sqeaking brakes

[Andy-Mat]

Not according to Shimano:

https://si.shimano.com/pdfs/si/SI-8JW0A-001-ENG.pdf

If you think that most discs are wrongly installed does that not make you question your thinking?

I am simply surprised that apparently nobody else here has tried it, other than myself....
Just as I suggested, only on a squealing front brake first.....easy to check, 5 minutes work, tops!
It would have helped to know either way on such a disk, which I have not got myself....
Are there no mechanical engineers here willing to try it out?
I believe that some/many/I cannot say, disks, the "spokes" are made far too thin, thus causing/exacerbating the problems.
But we do need someone else to make the effort to try it out.
I am already "trying it out"for over 18 months, with no problems whatsoever, on really cheap brakes....where I personally would expect problems first of all....
Iam really surprised at the lack of initiative....
Andy

 

[soundwave]

i run hope rotors and avid xo calipers which you are really not meant to do but i even had the older hope rotors that were for hope calipers only.

the only problems i have had with rotors are cheap one piece ones even the avid ones that came with my bike were crap as they got so hot they warped and was eating brake pads.

 

[awol]

This got me thinking about the bikes disc spoke directions pushing into the brake caliper and comparing that direction with my car brakes in that my car front brakes have the weight/power pushing into the brake calipers (like my bike) work better than my car rear brakes which have the weight/power pulling against the brake (like the bike disk reversed). Not sure if there is something in that?

 

[RossG]

awol is on the right track. On a bike disk brake much of the stress is that of shearing, and most of that is concentrated on the area immediately beneath where the radials extend down from the outer ring.
By making the radials curved and pointing towards the path of travel they're subject to less twisting force when braking is applied.
If you turn them the other way around the stresses on the radials are such they could well be torn from the outer ring. That's why all the manufactures put an arrow on their disks, they can't all be wrong.
It's an interesting theory but really a squeaky brake is just one of those things, the most important thing is to make sure it works correctly and stops you when it should. You can't argue with the laws of physics.

 

[Deleted member 25121]

awol is on the right track. On a bike disk brake much of the stress is that of shearing, and most of that is concentrated on the area immediately beneath where the radials extend down from the outer ring.
By making the radials curved and pointing towards the path of travel they're subject to less twisting force when braking is applied.
If you turn them the other way around the stresses on the radials are such they could well be torn from the outer ring. That's why all the manufactures put an arrow on their disks, they can't all be wrong.
It's an interesting theory but really a squeaky brake is just one of those things, the most important thing is to make sure it works correctly and stops you when it should. You can't argue with the laws of physics.

But the Young's moduli for steel in compression and expansion are almost the same, and you can't argue with the laws of physics...

 

[Nealh]

Rotor material and pad material are the two main factors .
Most cheap rotors are only suitable for resin/organic soft pads, semi - metallic pads are too hard and will either make them squeal like a pig or have little stopping power.
The only real option so it matters not which pad material you use is to upgrade said rotor, typically for Shimano options their Icetech range of rotors can be used with all pads and will do the job cost is about £20 a rotor.

I have used non resin pads on basic rotors for resin only and they have little bite/stopping power, upgrading the rotor solves the problem.
Cheap rotors use a one piece metal build usually stainless steel, better rotors are more heat resilient and use a laminate/ 3 ply metal sandwich of material.

 

[mike killay]

Well, having been thoroughly derailed, lets get back to the squeaking.
My problem was that I would set the brakes up just fine, but in no time they would start squeaking, not when braking but just going along.
I changed the front rotor which cured it, but feeling reluctant to going to all the bother of changing the rear one, I squirted it with citrus degreaser, gently applied the brake and rolled the bike forward to distribute the cleaner onto the pads, then used a strong hose pipe to thoroughly wash the disc and pads etc.
Seems to have worked, so I can only surmise that the problem was a build up of brake dust.
Andy-Mat need not reply!!

 

[Deleted member 25121]

Well, having been thoroughly derailed, lets get back to the squeaking.
My problem was that I would set the brakes up just fine, but in no time they would start squeaking, not when braking but just going along.
I changed the front rotor which cured it, but feeling reluctant to going to all the bother of changing the rear one, I squirted it with citrus degreaser, gently applied the brake and rolled the bike forward to distribute the cleaner onto the pads, then used a strong hose pipe to thoroughly wash the disc and pads etc.
Seems to have worked, so I can only surmise that the problem was a build up of brake dust.
Andy-Mat need not reply!!

Yes, it's certainly a good idea to keep the discs degreased.
It sounds as though one of the pads is touching the disc when the brakes are off, if the problem comes back it might be worthwhile using a feeler gauge to find out which pad is touching and then play around with the settings to centre the pads. I'm assuming they are mechanically operated.

 

[mike killay]

Yes, it's certainly a good idea to keep the discs degreased.
It sounds as though one of the pads is touching the disc when the brakes are off, if the problem comes back it might be worthwhile using a feeler gauge to find out which pad is touching and then play around with the settings to centre the pads. I'm assuming they are mechanically operated.

I think that you can understand why I am attracted by the elegant simplicity of Vee brakes. I have them on my folding bike and they are excellent.

 

[Deleted member 25121]

I think that you can understand why I am attracted by the elegant simplicity of Vee brakes. I have them on my folding bike and they are excellent.

Yes but they also need to be tweaked to stop them rubbing.
According to my book of words on cycle maintenance Avid mechanical calipers have one moving piston and and adjustments on both pads. The gap between the disc and the fixed pad needs to be around twice that between the disc and the moving pad.

 

[mike killay]

Yes but they also need to be tweaked to stop them rubbing.
According to my book of words on cycle maintenance Avid mechanical calipers have one moving piston and and adjustments on both pads. The gap between the disc and the fixed pad needs to be around twice that between the disc and the moving pad.

Yes, I have done all that.
But consider:- if you need to remove the wheel, it is almost impossible to put it back without slackening and retightening the pads. So much simpler with vee brakes. As to adjusting vee brakes, I do not find any problem to stop them rubbing.

 

[soundwave]

mine have 4 pistons and a right pita when one of them gets stuck so clean and lube them every 3 months.

Hope Silicon Lube - Out of Stock | Tredz Bikes

Hope Silicon Lube. Out of Stock. All Bike lubricants are delivered free to the UK mainland*, 365 day returns & Price Match.

www.tredz.co.uk

 

[Nealh]

I use the twin piston Shimano calliper that takes the B01S pad and have same model fitted to four bikes and have yet to have any issues with them.

 

[RossG]

But the Young's moduli for steel in compression and expansion are almost the same, and you can't argue with the laws of physics...

But in the instance we are talking about the dynamic is different so the rotational disk behaves differently.

 

[RossG]

Strange as it may seem I don't find squeaking brakes too much of a problem. If I'm riding along a cycle path country lane etc. and I cycle up behind someone slowly dawdling along I could ring a bell (don't use one though) crawl to a halt and wait till there's room to pass, shout out 'excuse me' or whatever.
Instead of all that I just touch my brakes and make them squeak on purpose, the walkers look round move to one side and smile as I ride past. Never had a problem with sharing a cycle path.

 

[Andy-Mat]

But the Young's moduli for steel in compression and expansion are almost the same, and you can't argue with the laws of physics...

 

[soundwave]

Strange as it may seem I don't find squeaking brakes too much of a problem. If I'm riding along a cycle path country lane etc. and I cycle up behind someone slowly dawdling along I could ring a bell (don't use one though) crawl to a halt and wait till there's room to pass, shout out 'excuse me' or whatever.
Instead of all that I just touch my brakes and make them squeak on purpose, the walkers look round move to one side and smile as I ride past. Never had a problem with sharing a cycle path.

vroooom

 

[RossG]

Love the overtake right on the edge of the path by the water...great stuff

 

[Deleted member 25121]

But in the instance we are talking about the dynamic is different so the rotational disk behaves differently.

What do you mean by "the dynamic" ?? Young's modulus is applicable to both stationary and rotating objects, and we're talking about the stresses in the spokes not the disc anyway.

 

[Deleted member 25121]

Strange as it may seem I don't find squeaking brakes too much of a problem. If I'm riding along a cycle path country lane etc. and I cycle up behind someone slowly dawdling along I could ring a bell (don't use one though) crawl to a halt and wait till there's room to pass, shout out 'excuse me' or whatever.
Instead of all that I just touch my brakes and make them squeak on purpose, the walkers look round move to one side and smile as I ride past. Never had a problem with sharing a cycle path.

Mike is experiencing a different problem, his brakes squeak when going along not when braking:
"My problem was that I would set the brakes up just fine, but in no time they would start squeaking, not when braking but just going along."