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  1. #1
    nimble biker
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    why does my front XT disc brake squealing under braking?

    why does my front XT disc brake squealing under braking?

    This is the new XT brake on my Pivot mach 5.7 carbon.

  2. #2
    mtbr member
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    Probably just the pad type. Take them out and look on the back of the pad. Probably metalic pads. Same thing happened to me so i changed them for Organic. Same power and feel only no noise and no heat-sink.

  3. #3
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    I replaced the Avid brakes on my 2011 Stumpjumper with Shimnao XT M785's after 3 months of use. The Avids couldn't be made quiet. So away they go.

    Now recently, I have also replaced my previously good performing Formula T1s which came stock on my 2013 Stumpjumper Carbon 29er, with, Shimano XT BR-M785s again... The Formulas also would not be quiet, and developed poor level feel, needing to be pumped up. Someone said "they need to be bled again, that's all"..... For those dolts who don't know that brakes are NOT SUPPOSED TO NEED BLEEDING ALL THE TIME, do yourself a favor and get Shimano's.

    Also, the T1 Formulas, did not have bad lines or fittings, both the front and rear developed mushy lever at the 3 month mark. I bled them (I am damn good at bike maintainence) and they they were good for a week, then slowly back to mush. No leak could be found, so therefore, crappy design requiring constant maintainence.

    Now the Shimano brakes have only 2 rides on them, but have perfect feel, power, and are very adjustable. They are also wickedly easy to bleed, because I did have to shorten both hoses.

    People may love their Formulas, Hopes, Avids, whatever, but my personal opinion is that Shimano brakes perform great and worth the $300 to swap out.

  4. #4
    El CicloPath!!!!!!!
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    Quote Originally Posted by Picard View Post
    why does my front XT disc brake squealing under braking?

    This is the new XT brake on my Pivot mach 5.7 carbon.
    What I've noticed lately with my bike, especially after going to a 180 rotor, is that under hard braking, the brake actually can twist the fork in such a way that the caliper shifts, causing it to rub the inside disc. After a few seconds, everything straightens out and it is fine. At first I though it was a sticky inside piston, but that was not the case. It would seem that the brake exerts so much force as to twist the fork. This only ocurs when I'm riding a steep fast down hill and use the brake to slow down hard.

    I think the front wheel really needs to be as tight as possible (without compromising the bearings of the hub) and be as stiff as to not twist.

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