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I'm fairly new to bicycling; apologies if this is a standard question but I couldn't figure out how to phrase it to search for it elsewhere.

I ride a KHS Urban-X with Kenda Kwest tires (just what it came with). I've gotten barely any use out of it since owning it, and it's been resting comfortably in the living room through the winter, so I decided today was a great day to get back on.

So I unscrewed the back tire cap, and began to hand-pump air into the tire. All seemed to go well, and the tire held pressure fine, but when I removed the tire pump, the pin appeared to remain pushed down slightly, and air flowed back out of the tire. I looked, and this is what I saw:

enter image description here

Several narrow gashes that appear as if the rubbed was ripped, cut, or separated somehow.

Questions

  • Is this a common occurrence? Again, I've ridden on this bike very little and thus filled up the tires even less. We have no animals and no bugs around that I know of that would gnaw or chew on such material.
  • Is this fixable, or is my tube completely shot? It would seem to me that the latter is the case.
  • Is there anything I can do to prevent this in the future? I use a hand pump but am gentle; would a stand-up pump be a better choice?
  • Do bike tires come with a standard warranty for cases like this, or do you know of any brands that do? If I have to purchase new tires, I'm going to purchase
  • Is there any kind of "off-season" maintenance that I should be performing on my bike that could prevent things like this?

Thanks in advance for any help you can give!

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4 Answers 4

up vote 10 down vote accepted

Most likely this is a result of riding the tire while the pressure is too low. When you do that the tube tends to slide around in the tire and can get cut against the edge of the rim.

However, this could also be the result of using a hand pump, which, if you don't "buck" it against something or hold the head steady will move the stem back and forth rather violently. A "floor pump" prevents this sort of damage (and also makes inflation much easier).

The tube is toast. However, this is not a particularly expensive repair. A new tube will run you $5-10, and replacing it is something you need to learn to do anyway.

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It looks like I'll be investing in a floor pump, as it's the most likely culprit. Thanks! –  SeanKilleen Apr 11 '12 at 0:52
2  
Make sure you inflate the tires to proper pressure before each ride. A bicycle tube loses a small percentage of the air in the tube each day. It only takes a few days for the pressure to be low enough to cause this kind of damage. –  zenbike Apr 11 '12 at 7:39
    
@goober, a floor pump makes it easy, but it's still possible to keep a hand pump steady. I grip the spokes with my finger and let the tire and pump push against my palm. –  amcnabb May 7 '12 at 18:04

If using a Presta valve this can be caused by having the stem nut done up to tightly (effectively trying to pull he stem through the rim)

Not the case here, but maybe useful for future searchers.

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If this issue persists (i.e. your tubes keep failing near the valve stem), then you likely have a "sharp" rim or burred valve hole.

While you can try and file this down a bit, I've always found it simpler to get about 4cm x 2cm of old tube, cut a 5mm slice into it, and then push the valve through this.

This will mean that you have tube => valve through old tube => valve through sharp valve hole. Any damage will be done only to the old tube.

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This could be caused by a tube that was installed with the valve not perpendicular to the rim. It's quite a common problem, and I don't believe that a patch will work because they're designed to work on flat rubber.

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I've managed to fix holes like this with patches, but the result was very unreliable and a lot more work than just replacing the tube. I won't fix'em anymore. –  heltonbiker Apr 11 '12 at 0:30

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