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Old 06-23-07, 09:30 PM   #1
sknhgy 
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brake pads rub on rim

I know this must sound like a simple problem, but I can't fix it.
My bike has Shimano v-brakes. They pull from one side. Seems like a brake pad on one side always wants to contact the rim at a high spot on the rim.
How do you move the brake pad away from the rim and make it stay there?
If I turn in the screw that adjusts the tension on the spring, it will move the pad away from the rim, but it seems like it alwys moves back after a while and starts rubbing again.
Can anyone help me with this?
BTW, I did a search but didn't find this problem being addressed. Please bear with me.
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Old 06-23-07, 10:22 PM   #2
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check the trueness of the rim
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Old 06-23-07, 10:27 PM   #3
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Three possibilities:

– If it rubs only in one point, your rim might be out of true. And if if wobbles more and more, it might be because you have one broken spoke. Pluck all spokes to make sure it's not the case; replace the broken spoke (if it applies) and true the wheel.

– You didn't turn the screw enough. Turn "the screw that adjusts the tension on the spring"; there usually is one on each arm, so release one and tighten the other one. Squeeze the brakes a few times to get rid of any leftover resistance and see what happens. If you can tighten on both sides, it may be better to tighten both screws a bit to increase overall spring tension.

– One or both pivots need grease. That's especially plausible if you ride through winter or other bad conditions. Remove the cable, remove the pivot bolt that holds the arm, then remove the arm.
Clean pivot and hole inside the arm with WD-40 or some other solvent/cleaner. Then put grease on the post, put the arm and put the bolt back in place.
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Old 06-23-07, 11:22 PM   #4
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Instead of playing with the fine adjustment screws, turn them all the way out, then just pop the linear spring (it looks like a straight wire behind the arm) out and give it a bend outward. Pop it back in place, then if that's not enough, try again til you get it close. The fine adjustment screws won't make up for weakened springs, but a bend outward will give the springs new life. Then you can try balancing the springs with the screws by turning them in.

The other posters had good advice too. True the wheel and make sure the arms move freely or all the spring bending will be academic.
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Old 06-24-07, 05:52 AM   #5
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Quote:
Originally Posted by Michel Gagnon
Three possibilities:

– One or both pivots need grease. That's especially plausible if you ride through winter or other bad conditions. Remove the cable, remove the pivot bolt that holds the arm, then remove the arm.
Clean pivot and hole inside the arm with WD-40 or some other solvent/cleaner. Then put grease on the post, put the arm and put the bolt back in place.

This one is my guess as well. Likely the side that rubs is the side that is close to seizing.
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Old 06-24-07, 07:08 AM   #6
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then just pop the linear spring (it looks like a straight wire behind the arm) out and give it a bend outward.
+1......this is the solution if the adjustment screws alone don't solve the problem. It's a very common problem (and solution) with linear pull brakes. Of course, as the others have said, you need to true the wheel, too. There shouldn't be a noticeable "high spot" on the rim-
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