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Old 10-18-07, 12:32 PM   #1
i_r_beej
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Increased rear brake cable drag- fix?

Hey all.

This is driving me nuts.

The bike is a year old. Cantilevers with 105 levers and in-line brake levers. I run Jagwire housing with Delta teflon coated cables. I use the same housing and cables on my road and MTB with excellent-- super smooth and light-- performance. I don't grease any of my cables-- it's never seemed to help and has only attracted dirt.

The drag on the rear brake cable seems to have increased over the last few months. The cables and housing are all less than 6 months old.

The rear cable stop was integrated with the seatpost collar and forced the cable to exit at an angle. The teflon was wearing off the cable so that was a dead giveaway for friction. I've replaced that weirdly designed unit with a conventional collar and cable hanger. Response is a little better. At least the lever returns to it's stop rather and being overcome with friction and leaving a couple of mm's of play.

But WTH?? Why is this "suddenly" so terrible? I'm having to run the spring tension on the cantilevers almost to maximum. This overcomes the drag but gives a really stiff feel at the brake lever.

I'm going to have to pull everything apart up to the lever I suppose. Maybe dirt/mud contamination at the lever? Something gotten down in the cable housing?

Any tips? Suggestions? Wisdom?

Thanks!
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Old 10-18-07, 06:24 PM   #2
Michel Gagnon
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Do you have the typical setup with open cable along the top tube ? If so, pull the cable by hand to see what happens. Normally, you should be able to apply the brakes by pulling the cable, and you should be able to pinpoint the problem.

1. The brake doesn't open up quickly

Then you have a problem with the brake. If you have used the bike a lot in dirty weather, the brake pivots might be dirty. On cantilever brakes, remove the brake arms, clean and grease pivots and re-install.
Or you might have a skewed brake or brake pivots due to some kind of collision.
Lastly, the curve around the seatpost might be so bad that it causes some problems. Sometimes using housing of a different length might help to get a more gentle curve.


2. The brake opens up quickly

Then the problem is with the brake levers or the front-end cable housing. First check where the cable housing reaches the top tube. I had a bike where the cable housing often got pinched and developed a kink fairly quickly. Rerouting is the only permanent solution.
Apart from that, I don't know about your inline levers as I never installed these, but I'm aware that with some brake levers, performance deteriorates significantly if the levers has been moved after installation. The 287-V levers are especially prone to that problem; move the brake lever by 10-20 degrees (the bike falls on the ground, for instance) and you suddenly have levers that don't work properly.
If you have problems in the front end, you might want to remove the handlebar tape and try to wiggle the housing to see if that solves the problem.

And finally, modern brake levers are spring loaded. There might be a broken spring in your lever... Although I should say that I have a lever with a broken spring; I needed to increase the tension in the brake arm, but once I did that, I find it's the best working brake lever I have.
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Old 10-18-07, 06:40 PM   #3
i_r_beej
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That's an excellent diagnostic technique. I've never hear of that! Thanks for that tip.

Now, off to my shop!
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Old 10-19-07, 07:52 AM   #4
tellyho
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Oil the cable.
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