rim brakes require constant re-centering
02-07-23, 11:56 AM
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rim brakes require constant re-centering
Not sure if this is just the sort of imprecision/slippage I should expect from ~16-year-old components, or if there's something amiss that can be easily addressed, but fwiw:
The Shimano Ultegra 6600 rim brake calipers on my 16-year-old Cannondale Synapse require re-centering practically every three weeks. The pivot bolt that afixes the brakes to the frame seems quite tight, I'm just re-centering them via the left/right pad adjustment screw on the caliper arm. And that screw seems like it's tight enough too, it doesn't seem like it even could be slipping (though I suppose that is a possibility...I haven't yet tried any ThreadLocker on those). But sure anough after a dozen rides or so one pad is always conspicuously closer to the rims than the other pad.
Seems to be more of an issue on the front brake than the rear.
And I'm not removing/replacing my wheels often enough for bad seating skewers to be the culprit.
Any ideas? Thanks.
The Shimano Ultegra 6600 rim brake calipers on my 16-year-old Cannondale Synapse require re-centering practically every three weeks. The pivot bolt that afixes the brakes to the frame seems quite tight, I'm just re-centering them via the left/right pad adjustment screw on the caliper arm. And that screw seems like it's tight enough too, it doesn't seem like it even could be slipping (though I suppose that is a possibility...I haven't yet tried any ThreadLocker on those). But sure anough after a dozen rides or so one pad is always conspicuously closer to the rims than the other pad.
Seems to be more of an issue on the front brake than the rear.
And I'm not removing/replacing my wheels often enough for bad seating skewers to be the culprit.
Any ideas? Thanks.
02-07-23, 12:42 PM
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It's the brake cable housing. The brake cable housing will push down on that side of the calipers if it's too long. Conversely it will yank up on the calipers if it's too short.
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02-07-23, 03:22 PM
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Icemilkcoffee is probably right about the cable but it couldn't hurt to recenter the mounting bolt at the frame. I've solved a bunch of off-centering road brakes this way.
02-07-23, 03:51 PM
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Just because the recessed nut is tight on the bolt doesn’t mean the caliper is tightly affixed to the frame. You may need a washer (or two) to take up the slack.
This is especially true if the cable is pushing or pulling the caliper out of position since that’s a fairly weak push/pull.
I’ve never centered a DP caliper using the little set screw- does yours actually change position between adjustments?
If not, just eyeball the clearance and leave that setscrew alone.
This is especially true if the cable is pushing or pulling the caliper out of position since that’s a fairly weak push/pull.
I’ve never centered a DP caliper using the little set screw- does yours actually change position between adjustments?
If not, just eyeball the clearance and leave that setscrew alone.
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02-09-23, 09:25 PM
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A little re-centering after you've removed and re-mounted a wheel is common. If you haven't been re-mounting wheels, look at the trueness of your rims. If they're off, it could be causing your caliper to recenter. Also, look at your initial centering job. The caliper is centered when the pads hit the rim simultaneously. The rim shouldn't move sideways when you apply the brake.
02-10-23, 04:58 AM
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Double pivot brakes don't act symmetrically. So what is perfectly centered when the brakes are in contact with the rim might be less centered when they are away.
Also, if you keep turning the centering screw, you're just making the brakes more asymmetrical. I would set that screw flush and then center the caliper by hand. That screw is only there for very fine adjustment.
Also, if you keep turning the centering screw, you're just making the brakes more asymmetrical. I would set that screw flush and then center the caliper by hand. That screw is only there for very fine adjustment.
Last edited by Kontact; 02-10-23 at 06:51 PM.
02-10-23, 08:55 AM
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Do you have a "star washer" between the caliper and the fork crown/brake bridge?
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02-10-23, 08:58 AM
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Originally Posted by JohnDThompson
Do you have a "star washer" between the caliper and the fork crown/brake bridge?
Are "Campy Magic Washers" even available commercially now?
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02-10-23, 02:19 PM
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Originally Posted by tiger1964
Are "Campy Magic Washers" even available commercially now?
https://www.amazon.com/Tektro-Serrat.../dp/B001CJX4JM
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