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Options for a small flat spot in rim?

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Options for a small flat spot in rim?

Old 10-20-16, 09:53 AM
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kewlkevkev
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Options for a small flat spot in rim?

I have a pair of CXP-21s laced to Ultegra hubs. At some point my rear wheel developed a flat spot (probably when a finished a ride with one less spoke than I started with?). I removed the tire and a few spokes and tried to push the spot out. Well now the wheel is (mostly) radially and laterally true, except there is still a small flat spot centered around one spoke, measured to be about 1mm off radially. Small, but annoying. The rim looked structurally fine to me when I had the tire and the tape off.

What are my options? Can I make my rim "rounder"? Any advice for relacing the hub on a new rim? Preferably it would match and the same spokes would work, so my easiest option would be to just get a CXP-21 rim. But that would mean paying $30 for shipping on ebay and hoping their rim is rounded than mine. I don't have a truing stand, dish stick, or tensiometer. But I do have a spoke key and patience.
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Old 10-20-16, 10:01 AM
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Is the flat spot exactly opposite of the valve? If so, it's the rim joint.
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Old 10-20-16, 10:21 AM
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Originally Posted by Bill Kapaun View Post
Is the flat spot exactly opposite of the valve? If so, it's the rim joint.
That's what I was going to guess.
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Old 10-20-16, 01:12 PM
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Originally Posted by kewlkevkev View Post
I have a pair of CXP-21s laced to Ultegra hubs. At some point my rear wheel developed a flat spot (probably when a finished a ride with one less spoke than I started with?). I removed the tire and a few spokes and tried to push the spot out. Well now the wheel is (mostly) radially and laterally true, except there is still a small flat spot centered around one spoke, measured to be about 1mm off radially. Small, but annoying. The rim looked structurally fine to me when I had the tire and the tape off.

What are my options? Can I make my rim "rounder"? Any advice for relacing the hub on a new rim? Preferably it would match and the same spokes would work, so my easiest option would be to just get a CXP-21 rim. But that would mean paying $30 for shipping on ebay and hoping their rim is rounded than mine. I don't have a truing stand, dish stick, or tensiometer. But I do have a spoke key and patience.
I believe that actually your easiest option is to just ride the wheel as is (and look at your bike less).
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Old 10-20-16, 01:29 PM
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Can you feel the flat spot? 1mm sounds small. If you can't feel it, try to forget about it.

If it really causes a problem, you can loosen all the spokes and apply force to the rim to bend it into shape. Of course, this is an inexact process. Then tighten all the spokes again.
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Old 10-20-16, 04:13 PM
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Originally Posted by AnkleWork View Post
I believe that actually your easiest option is to just ride the wheel as is (and look at your bike less).
Originally Posted by noglider View Post
Can you feel the flat spot? 1mm sounds small. If you can't feel it, try to forget about it.

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Old 10-20-16, 06:04 PM
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Originally Posted by Bill Kapaun View Post
Is the flat spot exactly opposite of the valve? If so, it's the rim joint.
It's about a spoke or two off from directly opposite.
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Old 10-20-16, 06:06 PM
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Originally Posted by noglider View Post
Can you feel the flat spot? 1mm sounds small. If you can't feel it, try to forget about it.

If it really causes a problem, you can loosen all the spokes and apply force to the rim to bend it into shape. Of course, this is an inexact process. Then tighten all the spokes again.
Yeah I can feel it and it's annoying, but that's probably what I'll end up doing. I should be less finicky about my old ass bike.
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Old 10-20-16, 07:45 PM
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I'd ignore it, personally. I have a flat spot similar to what you describe on one of my rear wheels, getting rid of the FS isnt possible and the wheel is good otherwise, so I just dont worry about it.
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Old 10-20-16, 07:59 PM
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For better precision, remove the rim, and scribe a circle on the floor. Beat the rim into shape to match the circle.
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Old 10-20-16, 11:12 PM
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attempting to get rid of that flat spot will likely ruin the joining point of that rim... leave it alone, or replace the rim.
over-tightening or loosening of spokes will cause unwanted stresses in the wheel.
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