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  1. #1
    mtbr member
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    May 2004
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    136

    new rotors, uneven power, why?

    I recently upgraded from Avid roundagons to clean sweep g3 rotors. I'm getting uneven braking power now, where the braking force seems to pulse. I upgraded the front first to a larger 185mms, and for the 1st two rides didn't notice anything wrong, and thought I was getting better brake feel from the larger rotor with a different design.

    Last week I got a new 160mm G3 for the rear, but this now is very uneven. The rotor is not out of true. I've been struggling with rear brake modulation and made several adjustments to the pads and the SD7 levers. But don't see how that could cause this problem.

    Today was my first ride with the new rear rotor and my 3rd ride with the G3 front. I had a big crash today on a descent that I've done many times over the past 6 years or so. It felt like the front wheel locked up just before I went over the bars. After the crash the front brake was locked up because the housing came out of the caliper and pulled the cable taught. Its possible I may have brushed a tree branch and jacked the cable housing. But I just don't remember hitting anything and felt like I was having a good clean run on this descent.

    After the crash I was very cautious while braking, and noticed that a similar pulsing on the front brake but much less noticeable than on the rear. The front rotor is true also. I've been running these BB7 brakes for at least 2 years now. And only started upgrading from the roundagons because I wanted a larger rotor up front, and liked the feel of the G3s better than the fingenails on the chalkboard kinda feel of the roundagons.

    Any ideas what could be causing this pulsing effect and what can be done to make it go away. I really do think that is what caused this crash. My guess is that my braking force on one of the weaker parts of the rotation was too much when force when the strong part of the rotor came around causing the front lock up.

    Thanks, Derek

  2. #2
    mtbr member
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    Aug 2008
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    It pretty much has to be something out of true. Have you put a dial indicator on the rotor, I've had a bent rotor after the bike fell over and I could not see it with my eyes but I had the pulsing and a dial indicator showed it.

  3. #3
    mtbr member
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    Sep 2007
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    2

    Same issue Juicy 3

    Front brake pulses with each wheel rotation. 08 Santa Cruz SL. Rotor and wheel appear true. Any suggestions appreciated.

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