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Rim wear

Old 10-07-15, 05:15 PM
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adavis84
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Rim wear

I have a set of used wheels that came with a frame I wanted. I'm a little worried, though, that the rims might not be usable. The hubs are in spectacular shape still and definitely worth relacing if I have to (Shimano XT M760).

Rims are Mavic A319



I don't have the type of caliper/micrometer to tell how thick the sidewall is, so I'm wondering if anyone wants to weigh-in on if these are safe to ride still (for light commuting and and around town).

Thanks!
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Old 10-07-15, 05:22 PM
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bikeman715
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they be fine for the type of riding you want to do .
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Old 10-07-15, 05:23 PM
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Are there no wear indicators or "dimples" anywhere on the braking surface that you can reference?
That amount of wear looks OK to me... "just keep an eye on it".
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Old 10-07-15, 05:25 PM
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Originally Posted by KLiNCK View Post
Are there no wear indicators or "dimples" anywhere on the braking surface that you can reference?
Not that I can find (which is what made me wonder).
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Old 10-07-15, 05:33 PM
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Thanks to both of you for the input!
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Old 10-07-15, 05:38 PM
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As stated above, that amount of wear doesn't look excessive.
Keep your pads and rims clean ("keep an eye on it" LOL) and enjoy many more miles of use.
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Old 10-07-15, 06:08 PM
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One good indicator of rim wear is how much the rim's flanges will flex further out/away from each other with tire pressure increase. Of course there's no chart or guide for this but if the rim width does increase a bunch do know that it's wall thickness is wearing thin. Andy.
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Old 10-07-15, 06:34 PM
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Originally Posted by Andrew R Stewart View Post
One good indicator of rim wear is how much the rim's flanges will flex further out/away from each other with tire pressure increase. Of course there's no chart or guide for this but if the rim width does increase a bunch do know that it's wall thickness is wearing thin. Andy.
Thanks for the tip! I read something like this in another thread, but the rim tape was disintegrated and the tires that came with the set have some cracking in the outside of the sidewalls and I'm not sure I'd like to find out how strong those aren't. The only other 700 tires I have on hand are currently mounted on my road bike.
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Old 10-07-15, 06:46 PM
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Rims are extruded using the identical technology to how your favorite pasta shape is made. This is not a super precise method of making anything the wall thickness will vary along the length. If the rim has machined sidewalls, that will increase the variance.

You can use this imprecision to advantage as a wear gauge. As the rim wears some areas will approach minimum thickness sooner than the rest of the rim. As Andrew pointed out, the thinner wall will flex out more when the tire is inflated. Since the wall varies, when it starts to sag under load, it will do so in some places sooner than others and produce a telltale pulsed braking action. Of course, better more precise rims may not give you the same warning, but most ims will.

If you're really concerned, you can use this safety method. Inflate the tire to 10-20% above riding pressure. If the rim can handle that load, dropping back to riding pressure will give you a 10-20% safety margin.

However, like the others, I believe you have a long time to go before you need to worry.
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