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I performed the experiment - brake pad toe-in

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I performed the experiment - brake pad toe-in

Old 08-12-22, 02:19 PM
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I performed the experiment - brake pad toe-in

I have anodized rims on my Redcay (currently Ambrosio Synthesis Durex, but something else originally).The brakes have always screamed like banshees. It's been hanging in the basement for a long while, in large part due to the noise. Some time ago, I acquired a set of Modolo Sinterized pads & holders. My thinking was they might help wear down the anodizing on the brake tracks. After three rides, totally about 130 miles, I couldn't detect a difference than when I was using Campy pads (well, Kool-Stop) and holders.

So, on my ride today, I came to the conclusion that I should explore the possibility of adding some toe-in. It seems to me that many toe-in recommendations over the years involved twisting the calipers. That was something I wasn't willing to do (maybe for horribly cheap stamped steel calipers, but not for my Campy Record parts). I had received the Modolo parts for free. They were new and huge, so big I could only squeeze them between calipers and rims by sanding off some material and running with the quick releases wide open. I was willing to sacrifice them for the sake of science.

I wound up tapering them so the front is about 1.5-2.0 mm thicker than the back of the pads. The resulting profile looks pretty crude, but since these are going to wind up in something like the Box O' Crap, I didn't really care.



I used a sanding wheel on my Dremel. This generated a ton of brake pad dust. If you do this, WEAR YOUR MASK!



I haven't gone on an actual ride with the "new" pads yet, but did go up and down the street. Blessed silence! Once I get some new Campy holders for the Redcay (of course, I forgot what they were for and sold the originals out of my parts bin. I will also have to rig up some sort of jig to make a cleaner, smaller, and more reproducible cut. For the time being though, I won't be scaring the bejeezus out of anyone in my immediate surroundings.

Edit: I don't recall anybody explaining exactly why adding toe-in works, but I have a hypothesis (though no experimental data to back it up, so it's not a theory). I think when you squeeze the calipers they twist ever-so-slightly. As they try to return to their prior shape, they exert more force on the fronts of the holders. Some of you engineers who aced your dynamics classes in college feel free to chime in.
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Last edited by smontanaro; 08-12-22 at 02:24 PM. Reason: add my hypothesis
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Old 08-12-22, 03:55 PM
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Nice work. I've also filed a washed so it is thicker on one side than the other and used that between the nut and caliper to create toe-in. Filing the pads works, too.

Jobst Brandt on brake squeal:
https://www.sheldonbrown.com/brandt/brake-squeal.html
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Old 08-12-22, 03:59 PM
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Approved. I cut tapers into some Koolstop pads on my Monoplaners that were squealing at the slightest touch of the rim and now theyíre silent.

I just used a hacksaw.

Only did the front as the rear doesnít seem to squeal.
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Old 08-12-22, 05:26 PM
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This has gotten discussed on the Bob list and other spots over the many years, and it's fairly well proven.
I've been using a coarse wood rasp to remove material from the rear of some of my problematic brake pads in a similar fashion, and have seen reduced squealing.

I will add that I've had more troubles with KoolStop red brake pads, which seem to get stickier in humid conditions (i.e. summer here in the midwest). Older pads that have had a chance to harden are less sticky and less prone to squealing. Still, I've been surprised that the red Koolstop pads in the Campy Record brakes on my Olmo can squeal enough on a soggy summer day that it will cause the quick release lever to gradually open up! Some additional work with the rasp has improved the behavior, although I'm not sure that it is completely cured.

Steve in Peoria
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Old 08-13-22, 11:19 AM
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NB: Iíve read that some of the older Modolo sinterized pads may contain asbestos. Itís pretty much always a good idea to wear a mask when sanding IMO.
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Old 08-13-22, 11:43 AM
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Definately a Win, Win...

In that all my bikes are Frankenized I have had no problems grafting newer style brake pads on to my vintage brake sets. On vintage Universal Brake Sets I was able to eliminate squeal by just dyking about 1/8"-3mm off the front corner of the pads. It was a crude solution. Sanding them down nice a pretty is better...
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Old 08-13-22, 02:22 PM
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Skip,
I think the squealing is a result of vibration in the pad caused by the action of the rear catching first and creating the vibration. We used to use a bit of the carboard from the brake pad shipping card and position it between the pad and the rim. It allowed the pad to create the toe in to keep the vibrations from happening. In the early 80's the cantilever calipers had toe in adjusting washers that allowed for the same thing. Smiles, MH
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Old 08-13-22, 03:04 PM
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Originally Posted by jethin View Post
NB: Iíve read that some of the older Modolo sinterized pads may contain asbestos. Itís pretty much always a good idea to wear a mask when sanding IMO.
That is true and it is always a good idea to protect one's self from particulate suspended in the air. Good advice no matter what the substance but asbestos is the worst of the worst!
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Old 08-14-22, 06:21 AM
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The idea is to prevent the brake from self energizing, which is what happens if the rear of the pad has equal or greater contact pressure than the front (roughly speaking). If the brake is self energizing, the contact pressure is no longer fully under your control, due to twisting of the caliper arm causing the contact pressure at the rear of the pad to increase, causing further increase in braking force (that is the self energizing part), until the caliper deflects so much that the braking force finally reduces. The cycle repeats at a frequency determined by the system properties, which is typically in the audible range.
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Old 08-15-22, 10:25 AM
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Originally Posted by steelbikeguy View Post
This has gotten discussed on the Bob list and other spots over the many years, and it's fairly well proven.
I've been using a coarse wood rasp to remove material from the rear of some of my problematic brake pads in a similar fashion, and have seen reduced squealing.

I will add that I've had more troubles with KoolStop red brake pads, which seem to get stickier in humid conditions (i.e. summer here in the midwest). Older pads that have had a chance to harden are less sticky and less prone to squealing. Still, I've been surprised that the red Koolstop pads in the Campy Record brakes on my Olmo can squeal enough on a soggy summer day that it will cause the quick release lever to gradually open up! Some additional work with the rasp has improved the behavior, although I'm not sure that it is completely cured.

Steve in Peoria
On Mrs. Road Fan's Paul MiniMotos, I used the popsicle stick spacer trick to toe-in the shoes front and rear, taking advantage of the spherical washers provided on the Kool-Stops. Worked like a champ - smiling wife, good stopping, good pad positioning. Final positioning took a little while!

I was going to do the same thing on the Paul cantis on my 650b, but I must have done those last year or the year before - they brake very well and quietly.
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Old 08-15-22, 08:21 PM
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It seems logical that over time the natural wear of the brake pads will cause the rear to wear more than the front (due to twisting of the caliper and/or its mounting, under the force of braking), creating a taper that should diminish or eliminate the self-energizing property. But I have never had this happen, to the extent of eliminating squeal, in my own experience. If I didn't do something deliberately to angle the brake pads, they never got quiet on their own. Maybe I don't ride enough, or perhaps I don't use my brakes enough
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Old 08-16-22, 05:43 AM
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Originally Posted by old's'cool View Post
It seems logical that over time the natural wear of the brake pads will cause the rear to wear more than the front (due to twisting of the caliper and/or its mounting, under the force of braking), creating a taper that should diminish or eliminate the self-energizing property. But I have never had this happen, to the extent of eliminating squeal, in my own experience. If I didn't do something deliberately to angle the brake pads, they never got quiet on their own. Maybe I don't ride enough, or perhaps I don't use my brakes enough
My thought was that toe-in would eventually disappear as the front of the pad wears more (it contacts the rim first and the pressure would seem to be higher there). Eventually, I'd be back to a squealing system. That was what kept me from trying this experiment for so long.

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Old 08-16-22, 05:48 AM
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Originally Posted by smontanaro View Post
My thought was that toe-in would eventually disappear as the front of the pad wears more (it contacts the run first and the pressure would seem to be higher there). Eventually, if be back to a squealing system. That was what kept me from trying this experiment for so long.
This is my experience. On my off-topic fixed-gear commuter with a single V-brake up front. It has the proper washers to do a toe-in adjustment. It lasted about 6 months before the squeal came back. I decided I like it. Better and louder than any bell or horn.
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Old 08-16-22, 10:15 PM
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Originally Posted by Chuckk View Post
I use a belt sander to resurface old pads. It brings them back to functionality.
Emory board, and my nails look a lot better, to.
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Old 08-17-22, 06:43 AM
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Originally Posted by Chuckk View Post
Squalling brakes are the classic way of telling the rider in front of you that he's too slow.
I think the French did it on purpose - think of the knurled brake surface on some wheels.
The extremely loud freewheels of a decade or so ago were created for the same purpose.
Yeah, you're not the first person to say, that.

But I don't believe it. A squealing brake has a lot less stopping power than a properly adjusted brake.
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Old 08-17-22, 01:04 PM
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Originally Posted by rhm View Post
But I don't believe it. A squealing brake has a lot less stopping power than a properly adjusted brake.
I have a Schwinn Speedster with a Racer front brake and a Sturmey-Archer XRD3 rear (drum brake). I can manage with the somewhat reduced stopping power in front because there drum brake rear has loads. The squeal is an added bonus.
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Old 08-17-22, 01:53 PM
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Squealing brakes - the old Mafac RACERs! I used to set them up so moderate stops weren't too loud but if a car cut me off (Boston city traffic) I'd hit the front extra hard. Every pedestrian within a block would turn and look at me. I'd point to the driver. Eyes follow my point. Driver gets awakened from his stupor by the squeal, looks up - and everybody is looking at him! Driver slinks off like a guilty cat. It was rather fun and well worth the effort to dial in the squeal.
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Old 08-17-22, 01:57 PM
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Originally Posted by rhm View Post
Yeah, you're not the first person to say, that.

But I don't believe it. A squealing brake has a lot less stopping power than a properly adjusted brake.
I learn something new every day. I've done hard stops for 50 years on squealing brakes and never had any idea I actually wasn't stopping fast. (So that noise isn't coming from our kinetic energy being turned into sound waves but is coming from somewhere else?)
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Old 08-17-22, 02:47 PM
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Originally Posted by 79pmooney View Post
I learn something new every day. I've done hard stops for 50 years on squealing brakes and never had any idea I actually wasn't stopping fast. (So that noise isn't coming from our kinetic energy being turned into sound waves but is coming from somewhere else?)
Well, it varies. YMMV, as they say.

And yes, i have had that experience with MAFAC Racers, they can squeal and still stop the bike.
I've also had brakes that, when that squealing started, the brake had very little stopping power. The pads were basically bouncing off the rim at high frequency, not spending much time in contact with the rim.
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Old 08-18-22, 02:55 PM
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If my brakes are squealing, they do not work very well because I will only gently squeeze the lever until I turn around, get back to the garage, adjust the toe in, and try again. I've never had more trouble with Mafacs than any other vintage brake wrt squealing. A course Nicholson is my usual go to and there is plenty of material on vintage brake blocks.
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Old 08-18-22, 06:43 PM
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Toeíd in.

With a 106-miler in 2 days, I toe’d in the new pads using a third hand tool and 3 slivers of card stock. I think they are ready. The 11-36 cassette is ready, Di2 shifting smoothly with the Roadlink and the B-screw in half way. The +1 is ready to ride.

After a terrifying drive over Loveland Pass, I’m skipping the ride. Good thing, because her Edge 1000 failed as well as her Varia headlight. She’ll be using mine.

Appreciate the toe-in advice.
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Old 08-21-22, 11:54 AM
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Originally Posted by iab View Post
This is my experience. On my off-topic fixed-gear commuter with a single V-brake up front. It has the proper washers to do a toe-in adjustment. It lasted about 6 months before the squeal came back. I decided I like it. Better and louder than any bell or horn.
I'll see how that works with my wife's Terry. By refusing to ride her bike until I "got rid of that awful noise" she got this whole thing started. I want to think it will work out as you say!!
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