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Old 06-08-09, 11:42 PM   #1
Sdlong92
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Read Parktool, Still Have Dual-Pivot Brake Question.

Hello,

I did a search and have read (and re-read) the Parktool website as well as Sheldon Brown's site on adjusting dual pivot brakes but am still having an issue with my rear brake. I bought a used Fuji League to commute around on and the rear brake is not functioning correctly.

When i squeeze the brake handle there does not seem to be much resistance and I have to pull the handle almost all the way down to have the pads touch rim. Aside from that, when I release the handle the handle does not return to start position (even when I've removed slack and made the brake a bit stiffer). I think the problem as to do with mostly with tension on the rear brake, there doesn't seem to be enough for it to "open" after I release the handle.

Can someone send me to a link that shows explicitly how to set tension on the brake? Is it even possible to set tension? I have also checked the brake line, what I mean to say is that I've disconnected it from the brake, pulled on the handle and then tried pulling on the cable to get the handle to return to original position. There seems to be very little friction.

Thanks for any help! I can provide pictures if need be. It's late and I can't recall the particular brand of brakes at the moment.

Donny
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Old 06-09-09, 12:02 AM   #2
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Have you popped the springs loose from the retainer clips and bent them out to increase spring tension?

If not, all brakes tend to relax the springs in time. Re-bending them gives new life to non-snappy brakes.
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Old 06-09-09, 12:13 AM   #3
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Have you popped the springs loose from the retainer clips and bent them out to increase spring tension?

If not, all brakes tend to relax the springs in time. Re-bending them gives new life to non-snappy brakes.
Oh thanks, I'll try that out tomorrow when I get home. Is it hard to remove the springs? Actually, is it possible to bend them too far out? I'm not going to the straightening them out completely I assure you, but just wondering how much of a bend out I'm looking at.

Strangely, I am sure the front brake is of the same age as the rear brake as the bike was a one owner and he claimed to not have replaced any components. So wouldn't that mean the front brake should be exhibiting the same problem? But in even a more exaggerated form since it is used more than the rear so the spring should be weakened too right?

Thanks for the help, I truly appreciate it. This thing is driving me batty
-Donny
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Old 06-09-09, 05:30 AM   #4
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I highly doubt that the springs have relaxed. If they did, bending them is not the solution as any bend you put in won't yield any additional tension for very long as the wire will continue to relax (assuming the wire is overstressed already).

The real answer to your problem likely lies in a few different areas. First, since this is a used bike and you likely don't know the whole history, replace the brake cables and housing as a starting point. The rear brake housing on most road bikes is prone to corrosion and many bikes have a non-ideal routing for the housing which only compounds the issue.

While you have the cable removed, you'll have an oppurtunity to check the caliper out by itself. Squeeze it by hand and see if it returns properly. If not, either your pivots needs to be cleaned/lubed or the return springs themselves need some lubricant. The best way to clean and lube the pivots is to disassemble the whole caliper but you start by just adding a few drops of chain lube at each pivot. The springs should have some sort of plastic guide on the legs where they contact the caliper arms to reduce friction. Check to make sure this piece is between the spring leg and arm as they can move over time especially if someone messed with the brake. Add some chain lube at these contact points as well. You'll know you have things working properly when the caliper moves freely and immediately springs back out when you let it go.

When you reconnect the cable, wind the barrel adjuster all the way in, pull the slack out of the cable by hand, hold the caliper closed against the rim (or just very close to it), and attach the cable. Use the barrel adjuster to fine tune your lever feel. Use the centering screws on the caliper to make sure both pads are an equal distance away from the rim. Note that you may need to true your rear rim a bit to be able to get the pads as close as possible without them rubbing somewhere else.
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Old 06-09-09, 05:47 AM   #5
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^ it actually is most likely the springs, just bend them out a bit. make sure both sides are even.
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Old 06-09-09, 05:59 AM   #6
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^ it actually is most likely the springs, just bend them out a bit. make sure both sides are even.
Explain to me why the caliper springs relax.
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Old 06-09-09, 06:03 AM   #7
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Wait are these not V brakes? :S
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Old 06-09-09, 06:53 AM   #8
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Regardless of what type of brakes they are, bending the springs is not the answer.
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Old 06-09-09, 07:53 AM   #9
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disconnect cable.... I bet brake springs are fine. cable/housings are probably gummed up or kinked.
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Old 06-09-09, 10:17 AM   #10
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disconnect cable.... I bet brake springs are fine. cable/housings are probably gummed up or kinked.
I'll throw my vote in for cables.
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Old 06-09-09, 11:46 AM   #11
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Thanks for all the replies. -lm still in class right now (on my phone) but will try out somethings when I get home. Do most people think its the cables and housing even though when the cables is disconnected from the brake the brake won't return when I manually squeeze them to the rim?

Thanks again everyone! Looking forward to getting home now as it's gonna be mid 70s . So close to getting a ride in.
-Donny
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Old 06-09-09, 12:57 PM   #12
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Do most people think its the cables and housing even though when the cables is disconnected from the brake the brake won't return when I manually squeeze them to the rim?
I swear you changed your post since I quickly read it this morning Just kidding, I somehow missed that in the original post.

Based on your description, the problem almost definitely lies in the pivots being gummed up or the springs needing some lubrication or repositioning of the plastic guides.
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Old 06-09-09, 04:31 PM   #13
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Problem Solved!

Solved! Thanks for all the input from every one. I decided after mucking about to bite the bullet and just take the whole thing apart to clean (omg there was so much crap, why is there sand inbetween the arms?). Then lubed and r-assembled. Seems to work much much better now, well anything was a step up from not working at all...but yeah they work pretty well now.

Thanks again,
-Donny
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Old 06-09-09, 04:34 PM   #14
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I swear you changed your post since I quickly read it this morning Just kidding, I somehow missed that in the original post.

Based on your description, the problem almost definitely lies in the pivots being gummed up or the springs needing some lubrication or repositioning of the plastic guides.
Haha, no you didn't miss anything. I think I forgot to mention that! It was late and I was sleepy! Thanks for your help!

-Donny
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