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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 12-30-12, 12:43 PM   #1
sknhgy 
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What to do with my bb5's?

Problem is I can't get the rotor not to drag while having good adjustment. I've tried truing the rotor with a cresent wrench. I've got most of the wobble out but it still rubs. I've noticed the pads do not wear, or are not worn, parallel with the rotor. Maybe I need new pads? Maybe I can sand the face of the pads to be parallel with the rotor?
I've thought of buying a new rotor, or upgrading the brakes to something better. Would an upgrade help, and if so, to what?
Here's how I adjust the brakes:
http://bluecollarmtb.com/2006/10/30/...l-disc-brakes/
Any suggestions?
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Old 12-30-12, 01:06 PM   #2
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The method I use is similar but not quite the same since most of what I adjust is hydrauilic(though I do have bb5s on my commuter mtb). The centering method is actually to retract the stationary pad most of the way back(leave a few clicks) then loosen the brake caliper mounts so it can slide but not significantly loose. Grip the brake lever firmly, drawing the caliper tight so that it follows it's own path to be tight. Hold very firmly and tighten the caliper bolts carefully a little at a time to avoid inducing any angles from the bolts. This will in most cases leave the caliper where it needs to be. Once tight, check your clearances with a light positioned on the opposite side and spin the wheel. Adjust the stationary pad clearance as needed. Then adjust the moving pad. Make sure your cable is not dragging against your pad retraction motion as this will keep you from getting your full clearance. I had a bit of trouble initially getting the cable drag free on mine.

If that does not produce enough clearance for your rotor, the rotor may just need to be replaced. It does happen.
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Old 12-30-12, 01:16 PM   #3
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That picture Via Jenson, looks like they left off the angle adjustable washers (just like on V- brake pads)
so maybe the whole caliper is askew.. my BB7, as supplied have them on both sides of the post mount -to ISO
adapter bolt.
That aligns the disc and the pads.. [hold the brake on then tighten the bolt.. ]



IDK, Cant see over the web, in text, (i'm old and, and hands on.. )

try going to a Bike Shop.. getting it up on the repair stand ,
high enough to see the clearances between the pads and the disc..

the concave/convex washers accumulate from V pad replacements,
so in the LBS there should be a collection of used ones.

IF you Upgrade to hydraulic , they self adjust for pad wear, automatically [ Like on Cars]
so may take care of that continuing need for attention,
rather than the need to keep it in adjustment yourself.. .
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Old 12-30-12, 04:15 PM   #4
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That brake adjustment tutorial is not mine. It's what I use for reference. I will try your methed, mtbrinpa, and see if it helps. Right now there is very little visible runout in the rotor but I still can't get a good adjustment without some drag. I can't see upgrading to hydraulic brakes. Would upgrading to bb 7's help?
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Old 12-30-12, 04:24 PM   #5
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Quote:
Would upgrading to bb 7's help?
try just buying a new, perfectly flat disc first..
new caliper would be in a set including another disc..

changes are not huge.. replacement pad is a different part, the inner pad adjustment is identical.
the outer pad adjustment moved from the barrel adjustment, on the cable, to a knob,
then there is no cable adjustment other than other end at the brake lever..
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Old 12-31-12, 12:50 AM   #6
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The BB5 is a basic brake. It's often very hard to set them up not to rub, depending on the disc mount alignment. The outer pad does not push in flush on a piston, it sits on a tilt when there's no tension on it. Sometimes the corner of the pad will drag very slightly. This can make an irritating noise in the stand but when the bike is rolling the noise is not noticeable, nor is the drag.

The best bet is to push the caliper as far outboard as possible, withdrawing the fixed pad, and set up the outer pad so that it sits flatter when there's no tension on the arm.

- Joel
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