Tube replacement
#1
Newbie
Thread Starter
Tube replacement
Hello!
Here's my story: Went out for a ride last week only to find that my front tire is flat. Pop it off, pull out the tube...don't see anything obvious. Feel around the inside of the tire...nothing pointy or sharp. Inflate the tube, can't find the leak. Inflate the tube some more and give it a listen...nothing. Inflate it some more and I find it! It's leaking at the base of the tube stem. So now I check the rim - no burrs or anything rough around the hole...rim tape looks good. So here's my question:
This tube has about 5000 miles on it - Does anyone change tubes every once in a while to avoid this? Do you think I missed something when I was checking the rim? Or do you think it was just one of those things that happens? Schrader tube BTW.
Thanks for your thoughts.
Here's my story: Went out for a ride last week only to find that my front tire is flat. Pop it off, pull out the tube...don't see anything obvious. Feel around the inside of the tire...nothing pointy or sharp. Inflate the tube, can't find the leak. Inflate the tube some more and give it a listen...nothing. Inflate it some more and I find it! It's leaking at the base of the tube stem. So now I check the rim - no burrs or anything rough around the hole...rim tape looks good. So here's my question:
This tube has about 5000 miles on it - Does anyone change tubes every once in a while to avoid this? Do you think I missed something when I was checking the rim? Or do you think it was just one of those things that happens? Schrader tube BTW.
Thanks for your thoughts.
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#3
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Check the stem hole in the rim. Make sure there are no burrs and I like to put a small bevel around the edge of the hole to reduce cuts. Nothing fancy, just take some fine grit sandpaper and lightly take the sharp edge off the hole. Not unusual for stems to get a cut at the base after enough miles but less likely if you don't wrestle it around when inflating and make sure it's perfectly straight coming out of the rim. You can also make a rubber washer from an old tube to slip over the stem and cover the base before installing the tube which adds a little more protection from cuts.
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#4
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To protect the next tube, I think those are great ideas. But bottom line now is, you need a new tube.
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#5
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Thread Starter
Thanks for the replies - Next time I have the wheel off I'll take a closer look at the hole again just to make sure I didn't miss something. Was wondering if there was something obvious I didn't know about. I like the "rubber washer" idea - will definitely do that. New tube already installed from my spare parts pile and so far so good!
#6
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Could be a valve hole burr, but it could also be too much bending and such from your pump head when you put it on and off.
Check your technique as well as your gear.
Check your technique as well as your gear.
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#7
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I've had many tubes fail at the bottom of the valve stem; I think it's a spot that's prone to failure as the valve stem wiggles in the hole and gets stressed by removing the pump. I use valve stem nuts, but not super tight, and they seem to help.
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#8
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Riding with under-inflated tires will allow the tire and tube to rotate on the rim and stress the valve stem, sometimes tearing it at the base.
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#9
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Most of my tube failures related to the valve stem start with a pump head that's too tight/small. When the pump is right, you'll still get an occasional failure, but it's generally random. No sense replacing a tube that's as likely to fail as the replacement is.
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#10
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The only thing I could think of that I did differently, is I may have used one of those small mini-pumps to pump up that tire a few days ago. I was digging thru my junk box and "found" and old Zefal mini pump and thought I'd see if it still works and how close I could get to 100 psi with it. I think I used the front wheel for the test. I usually use a floor pump in my garage or CO2 cartridge when on the road. So perhaps the action of using the handpump stressed the valve area. Good news is, the pump was actually fairly easy to achieve 80psi without much effort and now I carry it as an alternative to the CO2 for on road repairs.
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Another oddball cause of puncture is the rim tape. One time I had a rim tape that was sticking up at the edge of the u-shaped depression in the middle of the rim. This sticking-up edge eventually rubbed a slit in the inner tube. I fixed this by going to a wider rim tape.
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