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squeezing worn bicycle rim sound

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squeezing worn bicycle rim sound

Old 09-10-15, 08:34 AM
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squeezing worn bicycle rim sound

i have been doing some yearly maintenance on my bicycle, and started thinking about my rims. today, i googled some info on rim wear.

i squeezed the rim to see if it would flex, and it made a ultra high-pitch pop sound, almost like an electrical spark sound. i'm going to use a spare wheel.

do you think this had to do with spokes moving? do you think this was really the sound of a rim that is close to breaking?

my front rim is about 4 or 5 years old, using red brake pads, and concave between 0.3-0.5 mm.
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Old 09-10-15, 08:44 AM
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I don't know how you "squeezed" the rim, but your description of the sound reminds me of a nipple creaking in the rim, not anything to worry about (if that's what it was).

Most rims can tolerate thinning of the walls by over 1mm, so your 0.5mm shouldn't be an issue. You may eyeball the rim looking for circular stress cracks about the height of the inside reinforcement. Also know that as the rim thins to the critical limit, the walls become weaker, and the rim will bulge because of the side stress from the tire. That non-uniform bulging causes brakes to pulse noticibly and can be an early warning that you're close to the limit.
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Old 09-10-15, 08:45 AM
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Originally Posted by Lone
i have been doing some yearly maintenance on my bicycle, and started thinking about my rims. today, i googled some info on rim wear.

i squeezed the rim to see if it would flex, and it made a ultra high-pitch pop sound, almost like an electrical spark sound. i'm going to use a spare wheel.

do you think this had to do with spokes moving? do you think this was really the sound of a rim that is close to breaking?

my front rim is about 4 or 5 years old, using red brake pads, and concave between 0.3-0.5 mm.
If a spoke broke it will be beyond obvious that the rim is out of round and because one of the spokes will be not like the others that are straight and tight. The sound you heard was probably the sound of a twisted spoke untwisting which is a good thing because spoke twist is bad. It could have also been the sound of some interlaced spokes rubbing together. If the wheel is still straight, you should be fine to ride it. Do you have any idea how many miles you have on it? The only wear and tear you need to worry about is the brake surface getting thinner over thousands and thousands of miles. Everything else will present obvious problems like wheel trueness, hub binding, or a spoke breakage before a full failure.
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Old 09-10-15, 09:36 AM
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Some people I know would over inflate their tires by 10-15 psi and let them sit overnight to see if any cracking forms in the brake track and then drop back to riding pressures before taking the bike out if they did not form cracks overnight. I get the logic but not sure how safe/consistent that can be.

If you are concerned about it, contact the rim manufacturer and ask what their service limit is. I know some recommend as .5mm on lighter weight rims but many rims can handle much more than that. I personally go the route of replacing sooner rather than later because a rim is cheap and having had one split on me before after pushing it too far I decided it was not worth the risk for me.
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