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  1. #26
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    No the grommets are in the windows of the rotor,not as spacers

  2. #27
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    Quote Originally Posted by kcvpr View Post
    Brake squeal has more to do with improper brake bed in procedure than whether or not you use zipties for their supposed vibration dampening properties.

    Improper brake bedding causes microscopic 'hills and valleys' in the rotor and pads to form from the bedding layer of the brake pad not being evenly distributed on the rotor. This is why if you actually read the manual to your brakes they tell you not to lock up the brakes when breaking them in.

    When you improperly bed in your brakes you are basically turning your brakes into a phonograph. The rotor being the record and the pad being the needle.
    This is so true,i read all the time about people bedding there brakes in on a ride,disaster straight away,you have to bed brakes in proper and let them FULLY COOL DOWN.I have the xo trail brakes that a lot of people ***** about,i think there great brakes,no brake squeal because i bedded them in proper.Zip ties,e.t.c are only band aids.

  3. #28
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    Quote Originally Posted by kcvpr View Post
    Brake squeal has more to do with improper brake bed in procedure than whether or not you use zipties for their supposed vibration dampening properties.

    Improper brake bedding causes microscopic 'hills and valleys' in the rotor and pads to form from the bedding layer of the brake pad not being evenly distributed on the rotor. This is why if you actually read the manual to your brakes they tell you not to lock up the brakes when breaking them in.

    When you improperly bed in your brakes you are basically turning your brakes into a phonograph. The rotor being the record and the pad being the needle.
    Looks like SRAM agrees with you. From their Hydraulic Brake Overview:

    "Brake pads and friction
    Brake pads function on two principles: adherent friction and abrasive friction.
    Adherent friction begins with depositing a thin transfer layer of pad material on the rotor during an initial burnishing, or bed-in
    procedure. Once this layer is established, applying the brakes creates molecular bonds between the pads and the transfer layer on the
    rotor that are instantaneously established and then immediately broken, providing friction. Proper bed-in is absolutely critical to braking
    performance, as an uneven layer of pad material on the rotor can cause excessive noise and uneven braking. This may be imperceptible
    at first, but as the layer continues to build unevenly, these issues could arise after several rides.
    Adherent friction is the primary
    contributor to overall braking friction, and pad material is the key component in creating adherent friction. This is why pads wear much
    quicker than rotors."

    I'm definitely going to bed properly upon receipt of my new bike.

  4. #29
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    Quote Originally Posted by CCMTB View Post
    Looks like SRAM agrees with you. From their Hydraulic Brake Overview:

    "Brake pads and friction
    Brake pads function on two principles: adherent friction and abrasive friction.
    Adherent friction begins with depositing a thin transfer layer of pad material on the rotor during an initial burnishing, or bed-in
    procedure. Once this layer is established, applying the brakes creates molecular bonds between the pads and the transfer layer on the
    rotor that are instantaneously established and then immediately broken, providing friction. Proper bed-in is absolutely critical to braking
    performance, as an uneven layer of pad material on the rotor can cause excessive noise and uneven braking. This may be imperceptible
    at first, but as the layer continues to build unevenly, these issues could arise after several rides.
    Adherent friction is the primary
    contributor to overall braking friction, and pad material is the key component in creating adherent friction. This is why pads wear much
    quicker than rotors."

    I'm definitely going to bed properly upon receipt of my new bike.
    I read and kind of understand, but how do you PROPERLY bed in your brakes? Just by waiting for them to settle in? Does the squeal just go away after a while?
    roccowt.
    rocnbikemeld

  5. #30
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    Quote Originally Posted by CCMTB View Post
    I'm definitely going to bed properly upon receipt of my new bike.
    That's a very good idea, but probably not possible if your bike has been test ridden before like most bikes have when they sit in a bike shop for more than a few days. Because any bike shop that knows or cares about what they are doing will test ride every bike they do labor on, whether its new or old (like the shop I work at for example). The bed in procedure is not always done, or at least not all the way. As most bike shop mechanics dont have time to test ride a bike for 20-30min to properly bed in the brakes. This is further complicated by joe plumber who just jumps on the bike and grabs handfulls of the brakes whilly nilly.

    Quote Originally Posted by zarr View Post
    I read and kind of understand, but how do you PROPERLY bed in your brakes? Just by waiting for them to settle in? Does the squeal just go away after a while?
    The bed in procedure is something that should have been done when the brakes where new. The process is usually outlined in the owner's manual. But consists of several smooth but not complete stops from certain speeds repeatedly.

  6. #31
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    If all else fails try Squeal Out
    I used to ride to Win ... Now I ride to Grin

    While my guitar gently weeps, my bike sits there mocking me

  7. #32
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    So if they aren't bedded correctly and the adherent layer isn't properly laid down on the rotor, couldn't you just clean the crap out of the rotor then rebed them properly? That way you build a new adherent layer with proper bedding.

    Am I wrong in thinking this?

  8. #33
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    Quote Originally Posted by Kaizmuth View Post
    So if they aren't bedded correctly and the adherent layer isn't properly laid down on the rotor, couldn't you just clean the crap out of the rotor then rebed them properly? That way you build a new adherent layer with proper bedding.

    Am I wrong in thinking this?
    Take the pads out and give them a even sanding as they would be glazed from an improper bedding,and clean the rotor,might work

  9. #34
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    Kaizmuth, you're right to a point. Just cleaning them won't get the pad material out of the steel, though. The rotor needs to be sanded to get a new surface. A random orbit sander with 150 - 180 grit paper works well. Just the braking surface needs to be done. Do as Bruce said with the pads, but do them on a flat surface by hand.
    Magura has a good description of how to bed in brakes on their site.

  10. #35
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    I don't want to belittle any of the benefits of proper bedding because it sounds like there might be something there, but to "fix" brake squeal the OP and the one who put grommets in the holes to stop it were pretty wise. The reason brakes squeal is that the friction between pads and rotor cause the rotor to vibrate. If the vibrations happen around the resonant frequency of the rotors it causes the entire rotor to turn into a big speaker, exact same phenomenon as making a wine glass "sing" by rubbing its rim with a damp finger. One of the easiest ways to fix this is to change the resonant frequency of the rotor or dampen its vibrations, like wrapping duct rape around a wine glass, it won't sing any more. This can be done by either adding mass to the rotor (which will lower the frequency of the squeal) or add damping material which will help eliminate resonant vibrations.

    All that to say, if you have used brakes that squeal and are satisfied with their performance, just not the noise, try zip ties, grommets, etc. Otherwise sanded rotors and pads with a proper bedding procedure may work too.

  11. #36
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    Chrisem, if the rotors were properly bedded and working well with a good layer of pad material adhered to them, why would you need to rebed then if you are just switching pads? I understand that they won't be perfectly matched like the old ones, but that adherent layer is already there. Why wouldn't that just start working correctly right off? I can see some layer thickness difference from the new pads not matching up perfectly, but I'd think they would still work better than a new or clean rotor.

    I'm just trying to fully understand the logic behind the process here.

  12. #37
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    Quote Originally Posted by Kaizmuth View Post
    Chrisem, if the rotors were properly bedded and working well with a good layer of pad material adhered to them, why would you need to rebed then if you are just switching pads? I understand that they won't be perfectly matched like the old ones, but that adherent layer is already there. Why wouldn't that just start working correctly right off? I can see some layer thickness difference from the new pads not matching up perfectly, but I'd think they would still work better than a new or clean rotor.

    I'm just trying to fully understand the logic behind the process here.
    Because the new pads have a fresh layer of bed in material you have to burn through... And it never hurts to do things properly.

  13. #38
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    Kaizmuth, if they're bedded in and working well, you won't need to do anything to the rotor, or go through the bedding in process.
    If they weren't bedded in properly from new, then it's unlikely that the brake pad material has adhered evenly right around the rotor. It will be patchy with high and low points.This can cause vibration/squealing, affect modulation and reduce performance. Putting in new pads with a rotor like this, will just lead to the high spots getting higher, and the dreaded and embarrassing squeal will still be there.
    I was recommending sanding the rotors only if you are having these sorts of problems.

  14. #39
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    Quote Originally Posted by kneejerk View Post
    So, I tried putting some zip ties on my rear rotor to try and dampen the noise and it seems to have worked brilliantly. .
    well done, kneejerk. when i ued to machine brake rotors and drums, we would use a rubber dampening strip to accomplish what you have done there. like Ufdah said, the resonance in a squealing rotor like a singing wine glass.

  15. #40
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    i too had squeal that sounds like pigs being slaughtered! tried so many other ways but the squeal (turkey gobble) will return after a while......

    finally saw this post and tried your "zip tie mod" and works great! thanks a lot for this amazing tip!

    it even quiet down wet rotors! (i live in tropics and monsoon season is helluva wet and muddy here)
    awesome!

  16. #41
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    Interesting thread. Glad to know I'm not the only one with brakes that squeal like crazy. Mine only do it when wet, but it's really annoying.

  17. #42
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    Bed-in Procedure

    Quote Originally Posted by zarr View Post
    I read and kind of understand, but how do you PROPERLY bed in your brakes? Just by waiting for them to settle in? Does the squeal just go away after a while?
    From the Elixir Service manual:

    To safely achieve optimal results, remain seated on the bike during the entire bed-in procedure.
    1. Accelerate the bike to a moderate speed, then firmly apply the brakes until you are at walking speed. Repeat approximately twenty times.
    2. Accelerate the bike to a faster speed. Then very firmly apply the brakes until you are at walking speed. Repeat approximately ten times.
    IMPORTANT:
    Do not lock up the wheels at any point during the bed-in procedure.

    3. Allow the brakes to cool prior to any additional riding.
    Please donate to IMBA or your local IMBA chapter. It's trail karma.

  18. #43
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    Zip tie idea is fantastic! Even of it does melt o doubt it will do any harm. My rear squeals too. Can't wait to try this tonight! I'll give rep when I get home. Count on that!
    There's something about those long grueling climbs that gets my front end all stiff... And I'm not talking about lockout...

  19. #44
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    Putting the brakes to bed

    I'm really liking the idea of the zips. Although proper brake bedding is desirable, in the arena of mt. bikin' it seems unlikely that the rotors and pads will get anything but ground down to smithereens anyway, bedding or no bedding. I suspect that proper bedding will give you good brakes for a couple of rides, after that all bets off.
    P.S. I've had most of my brake issues with Avid's.

  20. #45
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    Quote Originally Posted by CCMTB View Post
    Repeat approximately twenty times.
    Or just buy some Shimano brakes.

    OP Great tip with the zip ties. I have a set of formula rotors which squeal. I'll have to try this.

  21. #46
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    Bye, bye Avid's

    Just took delivery of new XT's

  22. #47
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    Quote Originally Posted by Bikin Fool View Post
    I'm really liking the idea of the zips. Although proper brake bedding is desirable, in the arena of mt. bikin' it seems unlikely that the rotors and pads will get anything but ground down to smithereens anyway, bedding or no bedding. I suspect that proper bedding will give you good brakes for a couple of rides, after that all bets off.
    P.S. I've had most of my brake issues with Avid's.
    Glazed pads will make your rotor sound like a record player,

  23. #48
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    1. Accelerate the bike to a moderate speed, then firmly apply the brakes until you are at walking speed. Repeat approximately twenty times.

    uh oh. i think i only did this fifteen times today with my new pads...

    2. Accelerate the bike to a faster speed. Then very firmly apply the brakes until you are at walking speed. Repeat approximately ten times.

    and i think i only did this five times, maybe seven...

    i didn't lock the brakes during the process, though. (front brake, who wants to do that?) i was also sure to let them cool for about an hour. there was still a minimal amount of squeal but so far, so good.

  24. #49
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    I hear ya. I applied the brakes firmly ,i think, but perhaps not firmly enough, in step 1. then for step 2, i couldn't remember the instructions,so i applied the brakes quite firmly, rather than very firmly. have i ruined this set of pads?

  25. #50
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    Quote Originally Posted by Bill in Houston View Post
    I hear ya. I applied the brakes firmly ,i think, but perhaps not firmly enough, in step 1. then for step 2, i couldn't remember the instructions,so i applied the brakes quite firmly, rather than very firmly. have i ruined this set of pads?
    I wouldn't worry about it.

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