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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 09-13-09, 04:13 PM   #1
lognom
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Avid disc brake truing: am I the only one with this problem?

I recently bought a Avid bb7. The rotor that came with had +/- 0.030 runout, and even with the Park rotor truing tool I couldn't come close to truing it to a point where the caliper pads could be run all close together w/o rubbing the rotor. I then bought two Avid rotors from a local shop. Both out of round. The shop employee said it's the norm for (Avid?) rotors to be out of round out of the box and for truing to be frequently necessary, but Park says that it's usually better to simply chuck a non-tru rotor and buy a new one than to be take the trouble to tru.
Am I the only one with this problem? I don't think I'm setting up the brake wrong. The instructions on the Park website seem pretty clear. And even if I'm setting up the brakes incorrectly, I can see with my wheel truing stand and a dial indicator that the rotor has signicant runout.

Thanks.
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Old 09-13-09, 05:53 PM   #2
idcruiserman
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The stock rotor sucks IMO. I've had lots of trouble with warped ones. Upgrade to the clean sweep.
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Old 09-13-09, 06:55 PM   #3
Mike T.
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In ten years of disc brake use I haven't owned a rotor yet (out of about 8 sets of brakes) that didn't need truing. It's no big deal and takes just a few minutes. I prefer the Morningstar tools for the job - there's 3 of the tools and they work great -

http://www.morningstartools.com/drumstix.html

But then I have no problems with using just an adjustable wrench too.
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Old 09-14-09, 07:45 AM   #4
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Have you confirmed that it's not your hub that's not flat? Are you torquing the rotor down evenly? I bought two BB7 brakes a while back and when I laid the rotors on top of each other, they were perfectly flat.
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Old 09-14-09, 10:45 AM   #5
lognom
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Thanks for all your replies. I appreciate your input.
--Yes , I checked if the hub might be out-of-round and I used a torques wrench on the rotor bolts.
--I'll try the Morningstar tools.
--I'll try the Clean Sweep rotor.
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