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I'm on my third inner tube now and it's always the same problem: an oblong shaped rip on the part right behind the presta valve. I'm at a loss since instead of the valve side, these rips are appearing on the other side. I've been told this might be because the innertube gets folded inside but I'm always making sure to massage and bounce my tires. I really don't don't what to do since it's always just at the same place that this happens.

  • Are those tubes the same make or different brands? If they are the same make it could well be the result of aggressive folding during packaging, the stem of the valve punching the inside of the tube. – Carel Jul 10 '20 at 8:18
  • They are of different brands. I also inspected the last two for defects but they were fine before I used them. – Alexander Patrovsky Jul 10 '20 at 8:26
  • Are the tubes the correct size? Are you maybe tightening the flat nut on the valve too much? Are you using sufficient tire pressure? Do you press the valve inwards during the installation to prevent the tube being pinched between tire and rim? – Michael Jul 10 '20 at 9:39
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    How are you replacing the tube? Are you leaving the tire in place? If so, that means where the tube has failed was always pressed up against the same area of the tire. Check the inside of the tire where the tube is failing - CAREFULLY. The easiest safe way is to rub a cotton ball over the inside of the tire and see if anything catches fibers. Don't press your fingers against the tire, let the cotton ball "fluff out" from your fingers and use that part to rub against the tire. Road debris that works through a tire can be sharp and can easily slice a finger. – Andrew Henle Jul 10 '20 at 12:54
  • So the tear is on the outside of the tire, or on the inside where the valve sits? Could it be the valve stem sticking out into the tire too far? What kind of bike is this? What tire pressure? – cdonner Jul 10 '20 at 16:28
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I struggled with this once for a while.

One (duh) obvious thing to double-check. Valves usually have a little knurled and threaded ring. Be sure to remove that ring before inserting the valve through the hole in the wheel, and replace it afterward. Otherwise it's a way to push part of the valve body into the tire. The person writing this learned that the hard way.

Another (duh) obvious thing ... make sure the tire pressure is correct. If you don't have a pressure gauge you should get one. Best move: get a floor pump with a gauge.

Third thing. Get yourself some talcum power, put a bit into the tire and spread it around, by rotating the tire in your hand. It will lubricate the interface between the tire and the tube to let the tube adjust its position within the tire a little bit. That helps the tube from bunching up. Careful: Real talcum, not cornstarch powder. Talcum's a mineral with lubricative properties. And like other minerals that come in dust-tiny sizes (asbestos) you REALLY don't want any in your lungs so be careful.

Handling the tire to spread out the powder doubles as a way to inspect it carefully for sharp stuff and other tire damage.

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    Be aware that talcum powder is suspected to cause cancer. So at least do it outside and don’t breathe it in. – Michael Jul 11 '20 at 15:47
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Check that the rim strip isn’t spinning. It can spin during braking force and carry the tube with it tearing the tube away from the base of the valve.

If it is spinning you need to remove it and replace with a new strip or a few layers of tape of your favourite flavour.

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Also check the rim itself, underneath the rim tape. It is possible there's a sharper edge, a burr at a spoke hole or the valve hole. If you find something, try and deburr it with a deburring tool, or a larger drill bit, or a small file, or even a sharp knife can trim aluminium.

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