Andy ; with respect your posts are often unusual

 

I am an investigator by trade (not police though ) so I am a very evidence based person.

 

Show me evidence to prove your narrative and I'm sold. I'm open minded and well aware received wisdom is just that. Engineers and physicists etc discover or hone understandings daily.

 

However, don't expect me or anyone sensible to believe a theory that contradicts current best practice or knowledge without serious evidence.

 

A part of the skill of getting new ideas to gain traction is also How you give that message and not just What you say ie communication skills.

 

Pompousness, derision, put downs, self aggrandising, deliberate obfuscation, not answering questions asked and so forth. These are the trade marks of the bully, the delusional, the foolish and the internet troll.

 

So let's not go there then, eh?

I did not see any put downs, I did not mention any names either, so where is the problem? Could you be so Kind as to point that out.

I have had some poor experiences here with certain people, but I did not name them!

Did you in some way "feel" that you were being addressed personally?

But with regard to disk brakes and squealing, which is what this topic is about, just by observing how they are mounted, and being an engineer for a great many years now, I do believe that I can demonstrate to most people exactly how disks need to be used and why.

Though I will admit that an inkling on how metal behaves when hot might prove helpful as well.

Heavy people, aggressive riding, long down hill braking, temperature can probably easily exceed 500°F on almost any bike disk, though I have not got the equipment to measure the temperature, as they cool down as fast as they get hot.

But putting the disk through very quick cycles of temperature! Not helpful!

Let me say, that on several bikes with disk brakes, I have never had squealing, except when I once accidentally maladjusted the pads, one pad was lightly touching the disk without the brakes even being used!.....never when correctly adjusted!

Regards

Andy

I'll start with I suspect you of wilfully misunderstanding to be honest..

 

However let's do this just the once eh old chap?

 

" not see any put downs,"

 

Oh well, if that is your attitude to the sentence and post as a whole then I can only presume that it logically follows that you DID see "pompousness, derision, self aggrandising "

 

In your your own post.

 

Well....ok.

 

 

"I did not mention any names either, so where is the problem"

 

No problem , me neither. Nor did I mention names. Or even the mentioning of names.

 

So your point was answering a question that was not asked. Obvuscation mlud. Or deviation for the radio four listeners

 

 

Did you in some way "feel" that you were being addressed personally?

 

Um. Yeah. You responded to my post

 

"But with regard to disk brakes and squealing, which is what this topic is about, just by observing how they are mounted, and being an engineer for a great many years now, I do believe that I can demonstrate to most people exactly how disks need to be used and why.

Though I will admit that an inkling on how metal behaves when hot might prove helpful as well.

Heavy people, aggressive riding, long down hill braking, can probably easily exceed 500°F on almost any bike,though I have not got the equipment to measure the temperature, as they cool down as fast as they get hot. Putting the disk through quick cycles of temperature change...

Let me say, that on several bikes with disk brakes, I have never had squealing, except when I once accidentally maladjusted the pads, one pad was touching the disk without the brakes being used!.....never when correctly adjusted!"

 

Well, okay. Super duper.

 

Please do explain further . Preferably briefly and in a single post. With evidence.

 

Cheers

I'll start with I suspect you of wilfully misunderstanding to be honest..

 

However let's do this just the once eh old chap?

 

" not see any put downs,"

 

Oh well, if that is your attitude to the sentence and post as a whole then I can only presume that it logically follows that you DID see "pompousness, derision, self aggrandising "

 

In your your own post.

 

Well....ok.

 

 

"I did not mention any names either, so where is the problem"

 

No problem , me neither. Nor did I mention names. Or even the mentioning of names.

 

So your point was answering a question that was not asked. Obvuscation mlud. Or deviation for the radio four listeners

 

 

Did you in some way "feel" that you were being addressed personally?

 

Um. Yeah. You responded to my post

 

"But with regard to disk brakes and squealing, which is what this topic is about, just by observing how they are mounted, and being an engineer for a great many years now, I do believe that I can demonstrate to most people exactly how disks need to be used and why.

Though I will admit that an inkling on how metal behaves when hot might prove helpful as well.

Heavy people, aggressive riding, long down hill braking, can probably easily exceed 500°F on almost any bike,though I have not got the equipment to measure the temperature, as they cool down as fast as they get hot. Putting the disk through quick cycles of temperature change...

Let me say, that on several bikes with disk brakes, I have never had squealing, except when I once accidentally maladjusted the pads, one pad was touching the disk without the brakes being used!.....never when correctly adjusted!"

 

Well, okay. Super duper.

 

Please do explain further . Preferably briefly and in a single post. With evidence.

 

Cheers

I think that we apparently live in two totally different worlds..... (Thank the good Lord for that!)

You appear to be looking for an argument with someone, that's what I would call cyber bullying!

Please be so kind as to simply and permanently ignore all my topics, posts and comments in the future on any of the many forums that I frequent.

Many thanks for your full understanding in this matter.

Andy

Same as awol - i'm basing this on the direction of the spokes

For example, on a spoked bike wheel, the spokes are arranged, in tension, to keep the wheel stable in forward, backward, and even with pressure while riding, from either side.

If you look at probably most, but certainly not all disk brake rotors (I am speaking generally), they are also made with spokes, thin pieces of metal, that connect the outer "circle" of metal, to the hub, which they are usually connected to with either usually 6 or possibly 8 small screws.

Now if a bike wheel was spoked to tension the spokes in only one direction, not both, in reality it would fold up immediately, if it was used.

Well the brake disk is basically the same.

If the brake is used with the spokes pointing in the direction of travel, such as here:-

I am assuming for the moment that this disk has been photographed from the left of the bike, looking to the right, so that if moving forward, the disk is rotating anti clockwise.

Under heavy or long term (longer than say 30 seconds or so) usage of the brake, on say a steep downhill section in particular, the metal will get very hot. I have even seen disks (not on my bike!) that were almost black/blue from heat.

This heat softens up the metal (probably only) temporarily, and when the disk is used as in the first picture, it can form tiny waves, which when cooled, may cause the brakes to vibrate in an audible manner. Simply because the spokes are put into compression when braking, which I believe causes the distortion.

The thinner the spokes, the higher the temperature, the longer the heat is generated, the worse the effects.

I have not had brake squeal myself, but possibly, if the squealing disk is reversed, MAYBE if run hot again, my theory says that possibly the noise will be either reduced or even eliminated.

THEORY NOT TESTED YET!

But someone here might try it on say the front brake only, as that is mechanically the easy one to reverse.

Obviously, good quality designs in a good metal will still handle it better than a cheaper, thinner, low quality version.

Some disks are made quite thin, to save weight I believe, these will probably deform first. Guessing only.

The thicker disks will usually handle any heating effects far better in my limited experience. And although I have not bothered to weigh them and compare, the difference between thin and thick, it will probably be less than the weight of any small change some of us carry about in our pockets. e.g. Its not worth worrying about the difference in weight if you are just an average rider, like myself.

Now on a brake disk that runs the other way around, like this one:-

The heating may be identical, but the spokes are put into tension, stabilizing the outer ring from micro distortion far better.

Some disks are made so that they are stabilized, like a wheel, in both directions, these of course can be installed either way round with no problems, like this one for example, but are probably a few grams heavier still:-

Now if you look at this disk, you can see that each spoke is double, forming a very stiff and reliable double connection to each screw holding the disk, with the hub being made of far thicker (heavier!) metal. Thus reducing the chance or even totally preventing the distortion and therefore squealing.

I hope I have managed to make the reasons easy to understand, but if anyone has questions still, I will do my best to answer them.

regards to all

Andy

PS. I forgot to mention that I ride a fairly cheap bike and the disk brakes and calipers are definitely not of the highest quality or price. When the bike was delivered, either my bike or my mate's, one disk was reversed to the other!! The other bike had both disks (IMHO) reversed! Neither myself or my mate, and we both ride in the hills with the dogs, and it the town, have had no problems of squealing brakes. But I have had to repair the adjuster on the on the front brake, as it was plastic, as the Sun had got to it. As you can see here:-

I put some stainless steel parts together and replaced that plastic, and it now looks like this:-

Its hard to believe its the same brake and if anyone who has had the same problems, I have written an easy repair procedure that I can send anyone if required.

It really is simple, all you need are a few simple hand tools, and a stainless steel 8mm Allen screw, or a similar sized Torx screw, and a big SS washer and some 2 component glue!

For example, on a spoked bike wheel, the spokes are arranged, in tension, to keep the wheel stable in forward, backward, and even with pressure while riding, from either side.

If you look at probably most, but certainly not all disk brake rotors (I am speaking generally), they are also made with spokes, thin pieces of metal, that connect the outer "circle" of metal, to the hub, which they are usually connected to with either usually 6 or possibly 8 small screws.

Now if a bike wheel was spoked to tension the spokes in only one direction, not both, in reality it would fold up immediately, if it was used.

Well the brake disk is basically the same.

If the brake is used with the spokes pointing in the direction of travel, such as here:-

[ATTACH=full]31744[/ATTACH]

I am assuming for the moment that this disk has been photographed from the left of the bike, looking to the right, so that if moving forward, the disk is rotating anti clockwise.

Under heavy or long term (longer than say 30 seconds or so) usage of the brake, on say a steep downhill section in particular, the metal will get very hot. I have even seen disks (not on my bike!) that were almost black/blue from heat.

This heat softens up the metal (probably only) temporarily, and when the disk is used as in the first picture, it can form tiny waves, which when cooled, may cause the brakes to vibrate in an audible manner. Simply because the spokes are put into compression when braking, which I believe causes the distortion.

The thinner the spokes, the higher the temperature, the longer the heat is generated, the worse the effects.

I have not had brake squeal myself, but possibly, if the squealing disk is reversed, MAYBE if run hot again, my theory says that possibly the noise will be either reduced or even eliminated.

THEORY NOT TESTED YET!

But someone here might try it on say the front brake only, as that is mechanically the easy one to reverse.

Obviously, good quality designs in a good metal will still handle it better than a cheaper, thinner, low quality version.

Some disks are made quite thin, to save weight I believe, these will probably deform first. Guessing only.

The thicker disks will usually handle any heating effects far better in my limited experience. And although I have not bothered to weigh them and compare, the difference between thin and thick, it will probably be less than the weight of any small change some of us carry about in our pockets. e.g. Its not worth worrying about the difference in weight if you are just an average rider, like myself.

Now on a brake disk that runs the other way around, like this one:-

[ATTACH=full]31745[/ATTACH]

The heating may be identical, but the spokes are put into tension, stabilizing the outer ring from micro distortion far better.

Some disks are made so that they are stabilized, like a wheel, in both directions, these of course can be installed either way round with no problems, like this one for example, but are probably a few grams heavier still:-

[ATTACH=full]31747[/ATTACH]

Now if you look at this disk, you can see that each spoke is double, forming a very stiff and reliable double connection to each screw holding the disk, with the hub being made of far thicker (heavier!) metal. Thus reducing the chance or even totally preventing the distortion and therefore squealing.

I hope I have managed to make the reasons easy to understand, but if anyone has questions still, I will do my best to answer them.

regards to all

Andy

PS. I forgot to mention that I ride a fairly cheap bike and the disk brakes and calipers are definitely not of the highest quality or price. When the bike was delivered, either my bike or my mate's, one disk was reversed to the other!! The other bike had both disks (IMHO) reversed! Neither myself or my mate, and we both ride in the hills with the dogs, and it the town, have had no problems of squealing brakes. But I have had to repair the adjuster on the on the front brake, as it was plastic, as the Sun had got to it. As you can see here:-

[ATTACH=full]31748[/ATTACH]

I put some stainless steel parts together and replaced that plastic, and it now looks like this:-

[ATTACH=full]31749[/ATTACH]

Its hard to believe its the same brake and if anyone who has had the same problems, I have written an easy repair procedure that I can send anyone if required.

It really is simple, all you need are a few simple hand tools, and a stainless steel 8mm Allen screw, or a similar sized Torx screw, and a big SS washer and some 2 component glue!

I forgot to mention the quiz results, my apologies to all concerned:-

Answers for the Disk Brake Quiz are:-

1. Wrong. 2. Wrong. 3. Immaterial most likely. 4. Wrong. 5. Correct. 6. Immaterial.

7. Immaterial 8. Wrong. 9. Wrong. 10. Correct.

Assuming that my method is correct, look around you just to see haw many are wrongly, from an engineering point of view, wrongly mounted. IMHO most of them!!

Regards to all

Andy

Well, it's good to know that we have someone on this forum who knows more about disc brakes than Mr Shimano, Mr Tektro, Mr Avid etc. etc..

 

Should I write to Giant (Liv) and Forme, asking why they put the rotors on our bikes the wrong way round?

I forgot to mention the quiz results, my apologies to all concerned:-

Answers for the Disk Brake Quiz are:-

1. Wrong. 2. Wrong. 3. Immaterial most likely. 4. Wrong. 5. Correct. 6. Immaterial.

7. Immaterial 8. Wrong. 9. Wrong. 10. Correct.

Assuming that my method is correct, look around you just to see haw many are wrongly, from an engineering point of view, wrongly mounted. IMHO most of them!!

Regards to all

Andy

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?

https://singletrackworld.com/forum/topic/rotor-direction-well-one-is-wrong/

I think that we apparently live in two totally different worlds..... (Thank the good Lord for that!)

You appear to be looking for an argument with someone, that's what I would call cyber bullying!

Please be so kind as to simply and permanently ignore all my topics, posts and comments in the future on any of the many forums that I frequent.

Many thanks for your full understanding in this matter.

Andy

 

I sure will

 

Its is largely drivel

 

I just feel sorry for those who come looking for advice and get you

"ebiker99, post: 516252, member: 25121"]

Not according to Shimano:

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

 

Nor Tektro - as an example

 

https://tektro.com/products.php?p=35

My Shimano disc works fine, is fitted according to the manufacturers instructions and has a direction arrow. According to Andy it is wrong though.

 

Now, maybe Shimano is incorrect but there must be a good reason that they state the importance of rotor rotation so I'm staying with that.

 

I think it is inapropriate for a member to give advice to others that goes against manufacturers instructions, especially with braking systems. If an individual wants to experiment knowing all the facts then thats up to them .

I came across this explanation for the direction of disc spokes, is reportedly came from Hayes in 2009. To summarise, with the sweeping spokes leading into the calipers, the spokes are put into compression from the centre outwards while braking and this opposes the stress imposed on the spokes from the outside inwards by the disc rims heating up. The net result is to lower stresses on the spokes:

 

"The reason for the spoke design is that there are two sources of stresses in the rotor. The first is mechanical stresses due to torque and the second is thermal stresses within the rotor. As the braking surface heats up, it expands. The inner portion of the rotor near the hub is comparatively much cooler. With the outer braking surface expanding with higher temperature and the temperature of the center remaining largely unchanged a thermal stress is imparted on the spokes. The spoke design is specified such that the mechanical stresses and the thermal stresses occur in opposite orientations, attempting to cancel each other out and lowering the total stress in spokes as opposed to adding together. The result is the “sweeping forward” spoke pattern."

 

This shows a typical Shimano disc, the arrows at the centre show that is should be mounted in such a way that it rotates anti-clockwise with the bike moving forwards:

My Shimano disc works fine, is fitted according to the manufacturers instructions and has a direction arrow. According to Andy it is wrong though.

 

Now, maybe Shimano is incorrect but there must be a good reason that they state the importance of rotor rotation so I'm staying with that.

 

I think it is inapropriate for a member to give advice to others that goes against manufacturers instructions, especially with braking systems. If an individual wants to experiment knowing all the facts then thats up to them .

I agree. In fact I think that the relevant posts should be removed.

We have no way of knowing whether Andy is a serious poster with a good understanding of engineering, or a wind blowing troll.

His posts could pose serious danger to someone who just happens across this site.

His battery postings are worse then this and as always I ignore his advice and in the main most of his posts as I suspect do a few others. His views mainly go against the grain of most practices used/expressed and his theories/explanations seem to to written in gobbledygook.

Edited August 24, 20196 yr by Nealh

I agree. In fact I think that the relevant posts should be removed.

We have no way of knowing whether Andy is a serious poster with a good understanding of engineering, or a wind blowing troll.

His posts could pose serious danger to someone who just happens across this site.

I think that the fact that he's not responded says it all.

They say don't feed the trolls but sometimes they are worth the effort, just for the laugh.

Anybody looking through this thread (any several others) would know not to treat him/her seriously.

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

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.

 

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?

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.

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...

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.

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!!

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.

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.

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.