Tube punctures on inside - what's the problem?

[jochta]

Is the puncture always in the same place? Have you taken the rim tape off and checked underneath for anything protruding?

John

[JohnW]

I'm by no means certain, but I think to get a big split like that the tyre must have not been seated properly so the tube bulged out and split, or perhaps a bit of tube was trapped the wrong side of the bead, bulged and split, or something like that.
I think that big split is caused by a bit of tube not constrained by the tyre bulging and splitting.....a defect I would expect to be small, and the tyre just deflate quietly.
...........over to the panel!

Yeah - despite what I said (see the post above), that is a rational and logical perception, and I suppose that on the basis that the tube was changed in less than perfect circumstances a "rushed job" may have resulted. And - in retrospect and following closer inspection of the photograph - the split isn't a straight, clean split - as the examples that I've experienced were.

One of the splits that I'm referring to was about an inch long, or perhaps a bit more - and neither of experiences were a result of trapping the tube between the rim and the tyre - definitely not. I have done that, as well.

Lets see what tonyf has to say.

[ignatius986]

My solution to this problem was to just buy a new wheel. There was nothing visibly wrong with the old one, but the sudden deflation and inside puncture kept happening, even when the tube was installed by proper bike mechanics.

Since I've had my new wheel, I've not had the problem (touch wood) again. ...But that doesn't mean that a new wheel is necessary in all cases.

The old wheel was an Alexrims something or other, the new one is a CFX by Mach 1: http://www.mach1.fr/composants/pages/jante.aspx?id=47

It cost £40 and seems to do the job...

[JohnW]

ignatius -
£40 seems a good price.
Did the whole wheel cost £40, or just the rim?
Was the wheel built for you or off the peg?
If it was built for you, was the rim rebuilt onto the original hub?
Does the site you linked us to have an English language option?
If you can remember - when it wears out - could you let us know how many miles it's done?
Please?

[531colin]

http://www.mach1.fr/composants/index.aspx
UK distributor is Raleigh....don't know how much they bring in!

[axel_knutt]

Once again, the hole was in the inside, directly next to the valve.

Do you mean round the base of the valve? You need to check that the valve hole in the rim doesn't have a sharp burr on it. On a lot of rims the valve hole is razor sharp, if this is the problem deburring the hole should fix it, but to be doubly sure I made a pair of leather washers to put on the base of the valve stems to protect them.

[ignatius986]

ignatius -
£40 seems a good price.
Did the whole wheel cost £40, or just the rim?
Was the wheel built for you or off the peg?
If it was built for you, was the rim rebuilt onto the original hub?
Does the site you linked us to have an English language option?
If you can remember - when it wears out - could you let us know how many miles it's done?
Please?

It was an entire wheel for £40 (I was surprised at the price too). I bought it off the peg from a small repair shop called Cycle Care on Earl's Court Road in London.

The site is has an English language page, you should be able to choose your language at the top right of the screen - if that doesn't work try starting from the homepage mach1.fr.

I'll try and remember to say when it wears out. I think at the moment it has probably done about 400 - 500 miles.

Once again, the hole was in the inside, directly next to the valve.

Do you mean round the base of the valve? You need to check that the valve hole in the rim doesn't have a sharp burr on it. On a lot of rims the valve hole is razor sharp, if this is the problem deburring the hole should fix it, but to be doubly sure I made a pair of leather washers to put on the base of the valve stems to protect them.

It's a good point, but no I meant the hole was about an inch to the left or right (can't remember which way) of the valve.

[Tonyf33]

That looks like a defective product to me. What make/brand was it - and which country was it made in?

Previously had a similar problem with a kona branded tube with the long vavle, this looks like a Kenda in design but as no country make, some unreadable mould markings but a yellow '71' in block lettering with a circle around it.

I'm by no means certain, but I think to get a big split like that the tyre must have not been seated properly so the tube bulged out and split, or perhaps a bit of tube was trapped the wrong side of the bead, bulged and split, or something like that.
I think that big split is caused by a bit of tube not constrained by the tyre bulging and splitting.....a defect I would expect to be small, and the tyre just deflate quietly.
...........over to the panel!

Tyre was deffo seated properly and there was absolutely no tube exposed/not constrained within the tyre. Certainly with the kevlar beading it's easier to fit and avoid pinching the tube when fitting but given where the split occured I can't see how it would split there even if it had being exposed.
Rim tapes all good underneath, no projections, previous tubes always fine aside from my stupidity as previously mentioned.
As I can't remember where I got the tube from will just put it down to bad tube, just seemed rather strange to pop 5 hours afterwards though especially at low pressure

[Steve]

In recent years I have found my tubes deforming into the spoke holes & eventually when the tubes get old enough I get punctures in these "pimples". It was worst with the non-adhesive type of rim tape but even Velox & Nutrak don't seem to cure the problem. Think I will try a couple of layers of insulating tape underneath to help stop it.

[531colin]

Try filling the nipple holes....you used to be able to buy bits of cork for this purpose. What pressure do you run?

[Steve]

Try filling the nipple holes....you used to be able to buy bits of cork for this purpose. What pressure do you run?

Only 6 - 7 bar

[ignatius986]

ignatius -
£40 seems a good price.
Did the whole wheel cost £40, or just the rim?
Was the wheel built for you or off the peg?
If it was built for you, was the rim rebuilt onto the original hub?
Does the site you linked us to have an English language option?
If you can remember - when it wears out - could you let us know how many miles it's done?
Please?

Hi John, the wheel gave up on me a couple of weeks ago. The lbs said that the bearings were worn out and that I might as well just get a new one.

It hadn't done that many miles - maybe 1,000? Perhaps a bit more, but not more than 1,500.

It went through being ridden five or six days a week for a period of about 5 months though - through the winter.