Puncture/inner tube problem

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Pendodave
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Joined: 3 Jun 2020, 8:27am

Puncture/inner tube problem

Post by Pendodave »

I've just experienced a coupe of punctures which are identical in location and type. Not related to a thorn etc.
The picture below shows the tube with the puncture location marked - it's on the opposite side to the valve. I assume the odd shape is normal for a semi inflated tube outwith the tyre.
I've recently changed tyres, so perhaps there is something about them (slightly thicker bead?).
So, a couple of possible causes occur to me.
1. I'm somehow putting the inner tube in wrong.
2. The inner is too big for the wheel. The wheel label reads 700x18c/23c ergo 622x13. I have 28/622 tyres on. The inner tube is a schwalbe size sv15 which has a number of numbers on the box ranging from 18-622 to 23-622.
3. Something I haven't thought of...

I'd appreciate some advice, as I am not convinced I can work out out for myself...)
20211130_105237.jpg
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531colin
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Location: North Yorkshire

Re: Puncture/inner tube problem

Post by 531colin »

No, the shape isn't normal.
It looks to me like you have put the tube in with a "pleat" and the edges of the pleat have abraded against the tyre.
why you get a pleat in the same place, I can't imagine?
Do you fit tubes with a bit of air in them? I do, but if there is too much air, you get pleats, because the tube is too big.

edit....a tube 23-622 is theoretically too small for a 28-622 tyre
Pendodave
Posts: 531
Joined: 3 Jun 2020, 8:27am

Re: Puncture/inner tube problem

Post by Pendodave »

531colin wrote: 30 Nov 2021, 12:45pm No, the shape isn't normal.
It looks to me like you have put the tube in with a "pleat" and the edges of the pleat have abraded against the tyre.
why you get a pleat in the same place, I can't imagine?
Do you fit tubes with a bit of air in them? I do, but if there is too much air, you get pleats, because the tube is too big.
Thanks.
Do you mean that it is slightly folded?
The thing is, in both the inner tubes that have punctured, the shape of the tube and puncture location is the same - directly under the valve. I don't remember having air in, but it's possible.
Maybe I'm not fitting the valve in properly? Is there a specific technique for avoiding this sort of thing?
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531colin
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Location: North Yorkshire

Re: Puncture/inner tube problem

Post by 531colin »

Yes, folded in on itself.
You photo goes fuzzy when I crank it up, but it looks to me there are stripes on the periphery of the misshapen bit caused by abrasion from the threads in the tyre carcase.
Re. the valve, just make sure you can push/pull it up and down and its all freely moving. Massage the tyre beads there, and a bit of french chalk won't hurt.
slowster
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Re: Puncture/inner tube problem

Post by slowster »

Pendodave wrote: 30 Nov 2021, 11:04am 1. I'm somehow putting the inner tube in wrong.
I suggest you compare your own technique with the Park Tool video guide (link starts at the tyre fitting part of the video):

https://www.youtube.com/watch?v=eqR6nlZNeU8&t=335s

That is not necessarily the only way and (surprisingly given Park Tool's usual thoroughness) there are a few small but useful tips missing in the whole video (such as 531Colin's advice to push the valve in to make sure sure that the tube is not trapped by the bead at that point*). If the tube does not have a long valve stem (as needed with modern deeper section rims), you can also insert it after fitting the first bead of the tyre.

*Another is keeping track of the orientation of the tube when removing it, which makes it easier to work out where in the tyre the object is that caused the puncture is, because the distance from the tube valve to the puncture will correspond to the distance from the part of the tyre over the valve hole. If you don't keep track of the orientation, you won't know whether a puncture is at, for example, 90 degrees or 270 degrees to the valve hole.
Pendodave
Posts: 531
Joined: 3 Jun 2020, 8:27am

Re: Puncture/inner tube problem

Post by Pendodave »

Thanks again all.
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531colin
Posts: 16083
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Puncture/inner tube problem

Post by 531colin »

Just occurred to me, there is a video of me fitting a tyre here...https://www.bing.com/videos/search?q=fi ... &FORM=VIRE
Ignore all the stuff about pedal straps, thats just for marathon plus tyres, just because they are so stiff.
gregoryoftours
Posts: 2234
Joined: 22 May 2011, 7:14pm

Re: Puncture/inner tube problem

Post by gregoryoftours »

An 18-23 tube is going to be stretched very thin in a 28mm tyre. I suspect that this is your main problem.
As above about the tube folding in on itself at the valve. I'd keep the valve pushed into the well of the tyre as you're fitting it, check it's not caught under the tyre bead at the valve once fitted and then pull it back out fully to inflate, fitting the valve nut at that time if it has one. That should prevent the valve getting hung up inside and the tube folding on itself.
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