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Old 09-11-13, 06:00 PM   #1
Planemaker
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Flats - What Am Doing Wrong

I run slime tubes and the last two days I have had overnight flats after installing a previously patched tube. Both tubes had a small hole on the inside of the tube about one half inch from the valve. I have checked the wheel liner, it appears to be ok and there are no foreign objects on the liner. The hole is too far away from the first spoke on either side of the valve opening. When I install the new tube I screw the nut on the presta valve as tight as possible but, I have noticed that while inflating the nut on the presta valve was not as tight as thought (the inflation creates about a 1/4 inch gap between the wheel and the nut).

The only thing that I can figure out is that while I am inflating the tire I am somehow pinching the tube at the valve.
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Old 09-11-13, 06:18 PM   #2
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Leave the nut off.
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Old 09-11-13, 06:30 PM   #3
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I don't know what brand tube you are using, but it is common for most tubes to be narrow at the valve stem area and then bulge out slightly. I always give up when there is a problem around the valve stem. It is possible that because you patched in the bulged area, that the tube stretched unevenly and the patch didn't hold. Also, personally i never use those presta valve nuts, because when you tightening them (and especially when you tighten them as tight as possible). you can actually pull the valve right out of the tube. Hope this helps. brian
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Old 09-11-13, 06:43 PM   #4
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I think Brian25 is on the right track. As to the nuts I use them but I only run them on far enough to keep the stem from pulling back through the rim while I mount the tire and tube then run them down almost to the rim after the tube is fully inflated but I never tighten them.
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Old 09-11-13, 06:52 PM   #5
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I would find it difficult to properly patch a slime tube. But, I find it difficult to properly patch any tube. However, given your problem, I would try a new tube (perhaps you have and I missed it).
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Old 09-11-13, 07:29 PM   #6
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I tighten the nut just enough not to rattle.

When I install a tube, I inflate just enough to full seat the bead and then let ALL the air out so the tube can "realign itself". Then pump up to normal pressure.
I also talc my tubes so they don't tend to stick to the tire carcass.
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Old 09-11-13, 08:11 PM   #7
Planemaker
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All,

Thanks for the advice. I have installed a new tube and it appears to be holding air just fine. Hopefully, I chalk this one up to operator error.
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Old 09-11-13, 11:15 PM   #8
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Quote:
Originally Posted by mkane77g View Post
Leave the nut off.
+1

I remove the nut on the valve stem when installing a new tube and toss it into a small container in my tool box. At last count there were 40 of them. I'm not sure when I started doing this but it does not seem all that long ago.
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Old 09-12-13, 12:31 AM   #9
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When you screw the nut down so the stem is tight before you get the tire in the rim there isn't enough room for the tire to fit properly over the tube. If you leave the tube loose, without tightening the nut down you can fit the tire into the bead properly with the tube "up" and inside the tire. Then, after inflating, tighten the nut. Normally tightening the nut does nothing and if you keep your tires inflated perfectly it probably makes no difference, but if you let your tire get a bit low on air and you have occasion to brake crazy hard you could conceivably cause the tire so rotate and damage the tube by putting force on the valve. Having the valve screwed down diminishes the chance that the valve will come under a strain like that. It simply holds it in place. Lots of people ignore their use.
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Old 09-12-13, 06:38 AM   #10
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Quote:
Originally Posted by digibud View Post
When you screw the nut down so the stem is tight before you get the tire in the rim there isn't enough room for the tire to fit properly over the tube. If you leave the tube loose, without tightening the nut down you can fit the tire into the bead properly with the tube "up" and inside the tire. Then, after inflating, tighten the nut. Normally tightening the nut does nothing and if you keep your tires inflated perfectly it probably makes no difference, but if you let your tire get a bit low on air and you have occasion to brake crazy hard you could conceivably cause the tire so rotate and damage the tube by putting force on the valve. Having the valve screwed down diminishes the chance that the valve will come under a strain like that. It simply holds it in place. Lots of people ignore their use.
I always thought the nut was to hold the stem in place while adding air to the tube...
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Old 09-12-13, 07:20 AM   #11
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[QUOTE=digibud;16057131 but if you let your tire get a bit low on air and you have occasion to brake crazy hard you could conceivably cause the tire so rotate and damage the tube by putting force on the valve. Having the valve screwed down diminishes the chance that the valve will come under a strain like that. It simply holds it in place. Lots of people ignore their use.[/QUOTE]

Having the valve screwed down will rip the valve from the tube if the tire and tube rotate on the rim. We never use nuts on dirt bikes just for this reason. Having this happen on a bicycle will happen once in 10 lifetimes.
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Old 09-12-13, 10:08 AM   #12
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It's all academic to me. I've been advised to both leave the nut off and to be sure to screw it down but so far I've only lived .8 of a lifetime so I've never even known anyone who has had this problem happen. I do know, however, that if I screw that nut down tight before I put the tire on, there isn't enough room to fit the tire around the tube properly. If screwing the nut down can be part of the problem when a tire slips, then what is the point in them in the first place?
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