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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 09-26-09, 12:29 AM   #1
sirious94
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My brakes is moving...

So i am right at the end of a build, and i have only one problem. When i set my front brake so that it does not rub against the bike and i pull the lever and release it, the brake moves so that the brake pad is not rubbing on the rim!

I have old (like 1982 old) Dia-compe brakes, and the rubbing occurs ALWAYS on the side opposite of the brake cable. Anyone know how i would fix this? I tried tightening the center bolt, but then the brakes would not re-open, and i cannot tighten a centering nut, because it only has two moving nuts (front and back)

I just can't figure it out, and they just started doing this... GRRR.
Please help. Thanks.
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Old 09-26-09, 01:08 AM   #2
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Originally Posted by sirious94 View Post
So i am right at the end of a build, and i have only one problem. When i set my front brake so that it does not rub against the bike and i pull the lever and release it, the brake moves so that the brake pad is not rubbing on the rim!

I have old (like 1982 old) Dia-compe brakes, and the rubbing occurs ALWAYS on the side opposite of the brake cable. Anyone know how i would fix this? I tried tightening the center bolt, but then the brakes would not re-open, and i cannot tighten a centering nut, because it only has two moving nuts (front and back)

I just can't figure it out, and they just started doing this... GRRR.
Please help. Thanks.
http://www.parktool.com/repair/readhowto.asp?id=22
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Old 09-26-09, 01:42 AM   #3
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Wait a minute. You release the brake. Then it doesn't touch the bike. As in hit the rim of the wheel? When you release the brake-lever, it shouldn't hit the rim. But it sounds like what you are saying (or trying to say) is that they don't evenly touch the rim. If so - read on:

The bolt on the front of the brake-mechanism, if you tighten it, will make the brake tighter - so it wont release. If this is the problem, loosen the bolt/nut slightly and try again. Proceed until you have it so it releases. If the brake-pads are at unequal distances from the rim: Loosen the bolt behind the brakes and move the brake body by hand to where they look equal in distance from the rim on both sides. Hold them with one hand and tighten the back nut down with your wrench. This might take a few attempts - but you'll get it.

I just had the same problem on a used 3-speed bike with Dia-Compe brakes. They are old - but they really are easy to adjust/service.

Happy Trails!
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Old 09-26-09, 06:18 AM   #4
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did you use the star washer between the brake and the fork?
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Old 09-26-09, 09:04 AM   #5
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Wait a minute. You release the brake. Then it doesn't touch the bike. As in hit the rim of the wheel? When you release the brake-lever, it shouldn't hit the rim. But it sounds like what you are saying (or trying to say) is that they don't evenly touch the rim.
no no, 1. they are even 2. i pull the brake lever 3. i release the brake lever 4. the brake does touch the rim.

I know it shouldn't, but it does, so thats why i am trying to fix it.

and as for the star nut, they are the same brakes from my old build, i am upgrading everything else, but i figured a brake is a brake.
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Old 09-26-09, 11:43 AM   #6
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To me, it sounds like you're holding the brake arms while tightening the mounting nut. Try this: just lightly snug-up the nut on mounting bolt. Squeeze the brake levers a few times to let the caliper settle in. Use a wrench on the flats that are just in front of the fork crown to center the brake. While holding it in that position with the wrench, use another wrench or allen key (depending on whether you have a recessed nut or not) and tighten the mounting nut.
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Old 09-26-09, 05:53 PM   #7
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What level of dia-compe brakes are these? Around this time, cheap bikes usually had horrible, cheapo, ineffective, impossible-to-adjust side-pulls. Expensive bikes had nice, good side-pulls. (Mid-level bikes often had center-pulls.)

But assuming they're "good" side-pulls, did you lubricate the center pivot bolt (and the bearing surfaces that stack on it--washers, bearing area on the calipers)? Are the cable and housing OK--sliding freely?

(And is the wheel true?)

[EDIT]
Just read the Park Tool page, and I would do all that first. If that didn't work, I'd disassemble the brakes and lubricate and reassemble, and follow the Park Tool page again. If that didn't work, I'd start trying to decide if the brakes are shot in some way I didn't notice when I had the brakes apart.

Last edited by mcgreivey; 09-26-09 at 06:02 PM.
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