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  1. #1
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    What's wrong with my SLX brakes?

    I love the power and modulation of my Shimano SLX brakes I put on my 2012 BMC TE29 hardtail a few months ago.

    When braking at speed, they are powerful and quiet. However, at slow speeds coming to a stop, they honk and are quite noisy. Is there something I possibly did wrong in the set-up or burn in? Any suggestions would be appreciated. Thanks!

  2. #2
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    In trouble shooting noise from the brakes, it's hard sometimes to determine where the noise is coming from OR what is causing the noise. However, noise will almost always be some kind of vibration. This could be from the pads bouncing around or the rotor vibrating and perhaps transferring to the frame.

    One piece of information is that it only occurs at slower speeds. This means it has something to do with harmonics that are tuned at the lower frequency.

    Bottom line, I do not have any real solutions for you, just some information to hopefully help you isolate and diagnose the problem.

    I used to have so much problems with noise from the Avid brakes. After much trouble shooting finally tried a different rotor. Went from Avid rotor to Ashima. I couldn't imagine how much of a difference that made. Which rotors are you using?

    Try this:
    Sanding the rotor down a bit and re-seat the pads. Maybe something is on the rotor causing a "sticky" situation?

    Sand the pads as well? Once again, maybe something's contaminating the pads/rotor?

    Is it both brakes, front and rear?

    Try sanding a radius to the leading edge of the pad so the leading edge isn't digging into the rotor?

    What happens if you rotate the pads (swap left and right side)?

    I know there are a lot of questions and no bonafide "It's gotta be this" kind of answer. Without actually seeing the bike, it's hard for me to form a real solution like that. Therefore, those are kind of the steps I'd go through to try and get to the bottom of your quandary. Good luck, be sure and post up what you find. I'm sure it'd be most helpful to others.

  3. #3
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    Clean your rotors with denatured alcohol. Just put some alcohol on an oil-free rag, spin the wheel and pinch the rotor with the rag. If you get black gunk off the rotor, you're dealing with oil contamination. If you're lucky, the noise will go away once the rotor is clean, and you go out and ride it for a few miles. If you're unlucky, and the noise is still there (after cleaning and a ride) then you need to replace your brake pads.

  4. #4
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    Also, take your pads out and clean them with the denatured alcohol too. I use a small cup filled with it, like a stans cup, and then dip cotton swabs into it and basically scrub the pads. I never dip the dirty end back in the alcohol. Just keep using a fresh end and eventually the pad won't make the swab dirty. Same goes for the rag .Wear some gloves. I use denatured a lot for work, and I don't think it is best to absorb the stuff into your hands for long periods of time.

    Swab your calipers and pistons while the pads are out as well.

  5. #5
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    Were the brakes bedded in correctly? If not, you will get noise at low speeds. Your LBS should have let you know that you need to do some controled stops (15) from 20mph to about 5 mph, then another 10 or so from 20mph to a complete stop. This will spread your brake material across you rotors and bed it into them. If you have not done this you will have spots of your rotor with out pad material and this will cause your pads to vrabrate and cause noise at low speeds. At high speeds it is not as noticable.

    Mark
    2012 XXL Carve Expert

  6. #6
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    Thanks for the input!

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