Tube starting to tear near valve stem - fixable?
09-17-19, 03:22 PM
#1
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Tube starting to tear near valve stem - fixable?
I have a tube which, when inflated outside of a tire, looks like it's starting to pull away from the reinforced oval of rubber around the base of the valve stem. I noticed the problem while I was pressure-testing the tube after patching a hole elsewhere. The tube still holds air, but you can see a couple of small cracks starting to form right at the seam where the rubber transitions from the thick base material to the normal tube wall material. Would it be effective to try to patch the tube at this point to reinforce the seam, or should I trash it? The patch would have to ride up onto the thicker rubber oval and bond to it, so hopefully it's made of the same rubber as the rest of the tube (which takes my Rema patches pretty well). It's a Schwalbe tube in case that matters.
09-17-19, 04:34 PM
#2
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Getting the patch to seal over the mold flash at the seam is likely to be a challenge, as is getting the patch to deal with the differential expansion of the different rubber thicknesses at that same spot. Since your investment is a patch and some time there is little to lose but I think that the probability of failure is high. Make certain that you abrade the patch area well and let the vulcanizing fluid dry thoroughly without blowing on it before applying the patch.
09-17-19, 04:42 PM
#3
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Give it a try but also be prepared to toss it. Tubes are cheap.
09-17-19, 06:09 PM
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For what tubes cost I would personally just toss it IMHO. Not worth risking an unnecessary a flat out on a ride, especially if you are on a high speed decent.
09-17-19, 06:15 PM
#5
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There's no good way to re-bond a valve to the rubber. You've already patched it once. You're not living in the apocalypse. You've got a Niner RDO. Let it die. Buy a tube.
09-18-19, 09:16 AM
#6
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Fair enough. It’s not worth the hassle or risk of getting a flat that could have been avoided. I’ll just recycle the tube into a chainstay protector or something.
09-18-19, 04:08 PM
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A tear right at the base of the valve stem is generally not repairable. If the defect is a few cm away from the base of the valve stem then you could absolutely put a patch over it.
