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Old 06-27-05, 01:39 PM   #1
wrinklefree
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I've done a ton of research on disc brake squeel on different forums. It seems to be an ongoing issue with all brands, although the symptoms are not always the same. Some people are getting cold brake squeel while others are getting hot squeel. Unlucky people are getting some sort of noise all the time. People have named contamination or misproper pad alignment as the culpit.

Some background:
I mounted my new BB7's about a week ago, and right out of the box, they never squeeled. After about 3 rides, I was getting pretty loud noises, only on the front, and only during heavy braking loads, such as slow steep declines. I noticed the rotors and pads had this sticky brake feel to it, which was causing the noise. When I midly grip the brake, that nice quiet grabbing noise was replaced with this sticky loud howling.

So on went the laytex gloves and off came the rotors and pads. I first tried cleaning the rotor and pads with dishwasing detergent, which seemed to help right away. the grabby feeling was back, but after a few stops it squeeled again.

Next I tried denatured alcohol and a light/med sanding block. I lightly sanded both sided of the rotor to remove the shinyness, and gave a light scrubbing to the pads. Cleaned everything with alcohol and went for a test ride. Well it sqealed like crazy right away until they warmed up. I went for a 20 mile run with my gf, and they only squeeled on occasion. Heavy braking under steep conditions still caused some rather loud noises.

Having a strong car background, I had the idea of using anti-squeel compound. For those who don't know, brake squeel is mainly caused by resonating brake pads which send strong vibrations to the rotor. This high temp compound is designed to quel some of this vibration. Since bike pads don't have shims, I lightly coated each backside of the pads, and let it dry. After a few hours, I went for a test ride. To my surprise, this made the biggest difference. The squeel is all but gone. I still get a little bit now and then,but a huge improvement in my book. However, since the compound comes in contact with the brake piston, I'm wondering if bits can somehow fall off and contaminate the pads. The solution would be to use a brake shim which cars often use. This will allow you to you use MORE anti-squeel compound, and form a denser, less vibration-prone disk pad. I'm going to try and cut a pair of shims and glue them to the back of the pads and see if that will help even more.

I'm SHOCKED that brake manufacturers don't include a simple clip-on shim along with some anti-squeel compound with their pads. Just seems like a simple solution that gets rid of the biggest complint with disc brakes. Sure this would increase the thickness of the pad assembly, but that can be EASILY solved with Avid's CPS.

Can anyone think of a reason not to do this?
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Old 06-27-05, 05:07 PM   #2
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I keep hearing of this squealing problem, but strangely enough have never experienced it after close to a year of using my brakes. I'd say from the eyes of the manufacturer, the experience could be subjective to the use and method of braking etc so that the costs (monetary or otherwise) of including the shim to resolve what may be a small problem experienced by a few users - doesn't justify their inclusion?
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Old 06-27-05, 09:40 PM   #3
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I recently bought a new bike with these brakes. They started squealing like crazy on the first ride.

I inspected them thoroughly when I got home, and noticed that they were not properly adjusted. The rotor was too close to the inside of the slot, which caused it to make contact with the caliper body when moderate pressure was placed on the pads.

I looked up the installation instructions on SRAM's web site, and adjusted them accordingly. HUGE difference.

These brakes are strong, smooth, and quiet. After a day of my v-brakes howling after getting muddy, I'm sold on the BBB7's.
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Old 06-27-05, 11:42 PM   #4
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Quote:
Originally Posted by wrinklefree
Next I tried denatured alcohol
This should have been the FIRST thing you tried
Quote:
Originally Posted by wrinklefree

Having a strong car background, I had the idea of using anti-squeel compound.
Which is designed for CARS that generate a LOT more heat than bicycles
Quote:
Originally Posted by wrinklefree
However, since the compound comes in contact with the brake piston, I'm wondering if bits can somehow fall off and contaminate the pads.
Enitirely possible and highly probable
Quote:
Originally Posted by wrinklefree
The solution would be to use a brake shim which cars often use.
No the solution would be to mount the brakes according to the the directions
Quote:
Originally Posted by wrinklefree
This will allow you to you use MORE anti-squeel compound, and form a denser, less vibration-prone disk pad.
Nevermind the engineering efforts that went into this design in the first place and the thousands of users who have never needed to add AUTOMOTIVE solutions
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Originally Posted by wrinklefree
I'm going to try and cut a pair of shims and glue them to the back of the pads and see if that will help even more.
Why not try setting them up according to the directions rather than trying to out think the engineers?
Quote:
Originally Posted by wrinklefree

I'm SHOCKED that brake manufacturers don't include a simple clip-on shim along with some anti-squeel compound with their pads.
Gee that would be because they designed them not to need external bandaids
Quote:
Originally Posted by wrinklefree
Just seems like a simple solution that gets rid of the biggest complint with disc brakes. Sure this would increase the thickness of the pad assembly, but that can be EASILY solved with Avid's CPS.
Quit putting the cart in front of the horse.
Quote:
Originally Posted by wrinklefree
Can anyone think of a reason not to do this?
Other than the fact that I've set up a great number of these and I've never had a squealing issue on a clean, dry, properly set up pair of Avids. Squealing is generally solved by making sure that the calipers and pads are installed correctly and adjusted according to the directions and ensuring that the pads and rotors are free of grease and oils or other contaminates.
Quote:
Originally Posted by buzzwire
I looked up the installation instructions on SRAM's web site, and adjusted them accordingly. HUGE difference.
Yup. It's amazing how many shops don't follow the directions. I can train a chimp to install these correctly, and I'm not talking one of those NASA chimps neither. I'm talking the throwing poo at the zoo type
Quote:
Originally Posted by buzzwire

These brakes are strong, smooth, and quiet. After a day of my v-brakes howling after getting muddy, I'm sold on the BBB7's.
You'd be hard pressed to get me to suggest anything else.
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Old 06-28-05, 12:14 AM   #5
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Why are you assuming these weren't installed properly? I followed the instructions to a T MANY times. Avid themselves admit occasional squeal is "normal". Try doing a search here and on mtbr, there's TONS of people with similar noises.
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Old 06-28-05, 12:18 AM   #6
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Originally Posted by wrinklefree
Why are you assuming these weren't installed properly? I followed the instructions to a T MANY times. Avid themselves admit occasional squeal is "normal". Try doing a search here and on mtbr, there's TONS of people with similar noises.
I tell the people here the same thing I'm telling you.

Follow the directions and only use denatured alcohol.

I personally run a set of Avid BB7's on my own ride and the only time I have squealing issues is when I get swamp water in there.

Why don't YOU do a search here and see how many times I have to explain "Denatured Alcohol" and "directions" when it comes to "disc brakes" especially of the "Avid" variety
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Old 06-28-05, 12:23 AM   #7
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Yes I've read your suggestions (which I tried), and they didn't work for ME. I'm just sharing what I've found from my own experiences.
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Old 06-28-05, 12:30 AM   #8
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Yes I've read your suggestions (which I tried), and they didn't work for ME. I'm just sharing what I've found from my own experiences.
I will never endorse the use of an Automotive anti-squeal or brake cleaning product on a bicycle disc system. Part of this is due to the fact that people who get paid a lot more than I do to design bicycle components have made it quite clear that automotive products are inappropriate for use with their systems save for the use of DOT fluid in certain brands and models
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