Tube problems

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tuco
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Tube problems

Postby tuco » Sun Jun 24, 2007 10:45 am

I've had a few, about 3 or 4 in total, tubes destroy themselves while I've been taking the floor pump off the valve after doing a pre race day tyre pressure check.
A hole has developed at the base of the valve stem. One even totally removed itself from the tube.

It's always the short valve stems with the thread on them. I've used the smooth, long stem, no thread valves without a problem. I've preferred the short stems because the pump doesn't like attaching to the long stem valves. Of course life is good if this is my biggest concern in life.

Is it the pump, the valve stem type or the way I'm taking the pump off the valve?

It's happened on more than one bike and there are no burs (spelling) on the rim.

Just thought I'd ask before I do a bulk purchase and then find the valve type is not 100% compatible with my BBB floor pump.

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sogood
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Postby sogood » Sun Jun 24, 2007 12:18 pm

Try a different brand of tube and see what happens. And yes, the pump connector can definitely make a difference. With my Topeak floor pump, I note that it has a habit of bending the central valve stem if I unscrew the little round nut all the way up. And I have lost a tube (thankfully one that already had 6 patches) as a result. But if I don't unscrew it all the way, then it works fine.

One other thing with the valve stem is that you shouldn't overtighten the outer round nut and stress the base of the stem. A lot of people throw both that and the valve cap away.
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mikesbytes
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Postby mikesbytes » Sun Jun 24, 2007 9:31 pm

It could be any of the 3 you mentioned plus the one sogood metioned.

The most likely is that you are twisting the valve stem when you put the pump on and/or take it off.
If the R-1 rule is broken, what happens to N+1?

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tuco
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Postby tuco » Mon Jun 25, 2007 9:35 am

mikesbytes wrote:It could be any of the 3 you mentioned plus the one sogood metioned.

The most likely is that you are twisting the valve stem when you put the pump on and/or take it off.
The nut isn't over tightened. If I have it on it sits there flapping in the breeze.

I don't twist the valve stem, it's more of a pull but it's very tight.

That nut on the tube side of the rim would be a better idea to stop the valve pulling through when I try to release the pump.

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LuckyPierre
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Postby LuckyPierre » Mon Jun 25, 2007 10:32 am

Sorry, but I can't help. I haven't had that problem - although I've bent the little 'presta pin' on a couple of tubes. I've worried about my knuckles as I try to get the pump head off the valve stem (threaded ones) a few times. I find that if I push with my thumbs it comes off the straighest and my knuckles don't cringe. I look for smooth stems whenever I can, but the most common 'smooth-stemmed' tubes here are Vittoria Ultralights - expensive and, I expect, easy to puncture. That said, I'm using them inside my Gatorskins until punctures convince me otherwise.
Oops, there was a reason for my response - I think that I have the same BBB pump as you do.
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tuco
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Postby tuco » Mon Jun 25, 2007 11:25 am

LuckyPierre wrote: Oops, there was a reason for my response - I think that I have the same BBB pump as you do.
That be him!

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europa
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Postby europa » Mon Jun 25, 2007 11:37 am

You wouldn't have this problem if you didn't pump your tyres up :D

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I had a good bike ... so I fixed it

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gururug
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Postby gururug » Mon Jun 25, 2007 1:45 pm

Yeah, sound like its related to the rim, not the tube.

Next time you have the tyres off, compare the valve holes from your front and rear rims. My guess is that the wheel that has the stuffed up tubes on it, will have a dfeormity or other with this hole.

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tallywhacker
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Postby tallywhacker » Mon Jun 25, 2007 2:37 pm

used to have this problem all the time. Made sure the valve hole on the inside of the rim had no sharp edges, also covered the hole with a bit of electrical tape and cut a little x in the tape over the hole so that when the valve went thru it was protected by a flap of tape. Seems to have worked.

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tuco
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Postby tuco » Mon Jun 25, 2007 2:55 pm

First thing I thought of was a sharp bits around the hole in the rim but I checked the holes and even gave then a file and sanding.

A sharp bit on the rim shouldn't make the entire valve stem part from the tube which is what happened on the last on.

None of the holes have formed while the bike has been in use, it's only when I've checked the pressures which is why I leaning towards the pump being too tight on the valve or the way I remove it from the valve.

I have a big weekend of racing coming up so I'll use the electrical tape to start with.

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sogood
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Postby sogood » Mon Jun 25, 2007 6:17 pm

If it's not the pump, handling, valve hole in the rim and overtightening of the nut, then two other issues worth considering are, a) Is the rim tape moves on the rim and caused the cut? b) Is the tube well powdered to permit it to slide easily against the tyre inner and rim? If not, it could twist and do funny things to the tube if you've left a twist in the tube during mounting.

If still not the cause, then you really have to think about whether you have had a bad batch of tubes. What brand of tube were you using?
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MichaelB
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Postby MichaelB » Tue Jun 26, 2007 9:55 am

sogood wrote: One other thing with the valve stem is that you shouldn't overtighten the outer round nut and stress the base of the stem. A lot of people throw both that and the valve cap away.
Changed the tyres over on the bike last night and paid particular attention to this area, and took soggod's advice in throwing away the nut at the base of the stem.

No problems visible on my tubes at all - but getting the pump head on tghe valve properly is something I need to parctice a lot more ... :roll:

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mikesbytes
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Postby mikesbytes » Tue Jun 26, 2007 6:31 pm

I don't bother with the locking nut and cap any more.

Don't know why but I've never broken the valve stem away from the tyre. I have bent the release knob a couple of times.
If the R-1 rule is broken, what happens to N+1?

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tuco
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Postby tuco » Thu Jun 28, 2007 9:39 am

I spoke to the lbs today about this issue and he said he has the same problem but with a different brand pump. He reckons it's the threaded stems which are the problem because they're thinker but some of the smooth stems are hard for the pump to grip so may have to be held on while pumping.

Seems it's a problem we all have to live with.

A variation of the electrical tape between the tube and the rim would be to use an old piece of tube. It'll do the same job but better.

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