Mystery wheel rub

Discuss light weight issues concerning road bikes & parts.
Alexandrumarian
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by Alexandrumarian

I have three wheelsets, two boras and one alloy, all show rub marks on the rear wheel, mostly nds. On the alloy the anodizing is gone and on the boras, the decals (and stickers) are melted and smeared. So what on earth could this be. It is not near the pads. It is not pothole related, there are no scratches etc...
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by Weenie


mattr
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by mattr

Is it the small plastic stud/nub in the fin below the pads. (if you are using shimano)

Alexandrumarian
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by Alexandrumarian

...campy
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Calnago
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by Calnago

I think it would have to be that the pads are, or were at some point, set a little low on the brake track. If if was just one set that this happened to I’d say maybe the decals were applied a bit too high, but given that it’s all sets, seems to indicate the brake pads are a bit too low.
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Alexandrumarian
Posts: 426
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Location: Romania

by Alexandrumarian

It is two different bikes and it has happened along the years. It just took me a while to take and show photos. I am quite careful about all adjustments, there is no way i would get out the door with the pads so ridiculously low.

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Calnago
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by Calnago

Its happened to me before on a set of Neutrons a long time ago. It’s easy to think they are perfectly set, until you see evidence that they weren’t. Sometimes as the pads wear significantly they may not be contacting the rim exactly as they were when new.
But aside from that, I don’t know what else it could possibly be.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

Alexandrumarian
Posts: 426
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Location: Romania

by Alexandrumarian

This photo shows the pad mounted as low as possible - it is still 3mm or more too high...
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mattr
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by mattr

wait until it wears out, the swing of the arm might make it worse. (or better)

Alexandrumarian
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by Alexandrumarian

It should go up when closed in...to visualize, make an U with your thumb and index. Now close them to a circle.

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Valy
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by Valy

Have you ever noticed a build-up of debris after rides under the pads or around the chain stays?

mattr
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by mattr

Alexandrumarian wrote:
Wed Jun 19, 2019 7:32 pm
It should go up when closed in...to visualize, make an U with your thumb and index. Now close them to a circle.
Erm, i've been doing this 30+ years, i know what it *should* do. But I don't know how badly you've set them up. Especially as you seem to have got a random wear line round your wheel, so something isn't right.

jfranci3
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by jfranci3

What are you cleaning the wheels with? Acetone?

Alexandrumarian
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by Alexandrumarian

@Valy. no, nothing unsual that i can remember.
@jfranci3 no, no hard chemicals. And the wear is unquestionably mechanic. The alu looks just like shoe rub on a crankarm.

@matt. Even if I was a total disaster and a mechanical idiot (and I am very far from being one believe me or not) - there is no way to mount those pads low enough to correspond with the wear. Also, the wear is not random. The areas with less or no wear on the alloy rim tend to correspond to a spoke - I imagine the rim is very slightly narrower or concave there from spoke tension.

jfranci3
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by jfranci3

How is that brake track made? Looks like it is machined rather than molded. They might have machined it after molding, then put that transistion strip down. Looks like the transition strip is over teh sticker, so they may mold a common rim for disc and rim, apply the sticker, and then put the brake track down? Have you looked at used wheelsets on ebay for this?

by Weenie


bm0p700f
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by bm0p700f

Its pad related. Its pad position. For what ever reason the pad is not making the contact with the rim that you think it should be.

To get the pad to sit lower you can file out the slots in the calipers by a couple of mm. I can understand that might make people nervous and I probably would not do it myself but so long as you dont dont hack 5mm out you should be fine.

Thinner pads might help the ones that are 8mm wide I mean.

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