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Help - Pinhole on inner side of my tube today

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Help - Pinhole on inner side of my tube today

Old 04-10-17, 06:23 PM
  #1  
SylvainG
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Help - Pinhole on inner side of my tube today

Hi,

Got a pinhole on the inner side of my rear wheel tube today, facing the rim, almost dead center, no abrasion apparent near the hole. Didn't happened going to work and was already flat before leaving from work so the hole happened while the bike was parked in my office?!? The hole is between two spokes and the tape on the inner side of the rim is smooth, nothing protruding.

The hole is very close to the tube's 'junction' (at least that's what it looks like), see picture. What could have caused that? Defect on the tube?

Rim is a Giant S-R2, tire is a Giant P-X1, don't know the brand of the tube. Tire is rated at a max of 85 psi and was inflated Saturday to 80 psi.

Thanks.
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Old 04-10-17, 06:36 PM
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If it's a double wall rim and uses thin rubber rim tape, the tube might have extruded through the spoke nipple hole just enough to cause a stress split. Thin rubber rim strips don't provide enough support with the deeply recessed spoke nipple holes in double wall rims.

Happened to my bike last year, about six months after installing a new double wall rim with thin rubber rim strip. Went flat overnight. When I checked the tube and rim strip there were more than a dozen dimpled places corresponding with the spoke nipple holes. The stress caused a tiny split in one part of the tube and with a magnifying glass I could see several more waiting to split open, corresponding with every dimpled area.

Replacing the thin rubber rim strip with thicker cloth tape provided more support and solved the problem. Velox, Nashbar, Zefal, all look and feel about the same, so don't worry about brand. Just get the cloth tape that's narrow enough to fit inside the rim's recess without going over the shoulders. If the tape is too wide it'll cause other problems -- mainly with seating the tire bead. You can trim wider tape to fit but it's a PITA. Easier to buy the cloth tape that's the right size.

Thin rubber rim strips are fine with single wall rims, as long as the spokes, nipples and hole edges don't have any burrs. And check for burrs while you're at it. I chamfered mine very carefully with a handheld spherical tool bit -- mounting it in a Dremel would risk cutting through too much material.
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Old 04-10-17, 06:47 PM
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Thanks for the reply. A Google search told me it's a double wall (don't know how to check that myself). Is the cloth tape something you would by at a fabric store? How to you connect both ends of the tape together? Surely not scotch tape.
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Old 04-10-17, 06:47 PM
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The location is suspect.

Use a screwdriver instead of a tire spoon to get it on or off the rim?

If it was at a spoke hole, I'd suggest a spoke may have poked it from some wicked messed up taco action.
Or maybe the hole was from badly mis-located rim tape, causing the tube to herniate down to the space between the double wall of the rim.

But it's not at a location that would cause either of those. So...was the tube twisted and the part with the hole actually rotated towards something protruding the tire? Unlikely, but not unheard of...Could it be the tube was rotated and got pinched between the bead and the rim? Maybe. It is more likely than the other option. Consider yourself lucky it didn't blow out while riding. That sux...It's happened to me several times.

That leaves the screwdriver option during installation as the most likely, given the information you have provided.

Originally Posted by SylvainG View Post
Hi,

Got a pinhole on the inner side of my rear wheel tube today, facing the rim, almost dead center, no abrasion apparent near the hole. Didn't happened going to work and was already flat before leaving from work so the hole happened while the bike was parked in my office?!? The hole is between two spokes and the tape on the inner side of the rim is smooth, nothing protruding.

The hole is very close to the tube's 'junction' (at least that's what it looks like), see picture. What could have caused that? Defect on the tube?

Rim is a Giant S-R2, tire is a Giant P-X1, don't know the brand of the tube. Tire is rated at a max of 85 psi and was inflated Saturday to 80 psi.

Thanks.
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Old 04-10-17, 07:04 PM
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Originally Posted by SylvainG View Post
Thanks for the reply. A Google search told me it's a double wall (don't know how to check that myself). Is the cloth tape something you would by at a fabric store? How to you connect both ends of the tape together? Surely not scotch tape.

Any bike shop will have it or you could order the tape on line. Its just tape with adhesive backing. forward video to 1:10.


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Old 04-10-17, 07:47 PM
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Originally Posted by base2 View Post
The location is suspect.

Use a screwdriver instead of a tire spoon to get it on or off the rim?

If it was at a spoke hole, I'd suggest a spoke may have poked it from some wicked messed up taco action.
Or maybe the hole was from badly mis-located rim tape, causing the tube to herniate down to the space between the double wall of the rim.

But it's not at a location that would cause either of those. So...was the tube twisted and the part with the hole actually rotated towards something protruding the tire? Unlikely, but not unheard of...Could it be the tube was rotated and got pinched between the bead and the rim? Maybe. It is more likely than the other option. Consider yourself lucky it didn't blow out while riding. That sux...It's happened to me several times.

That leaves the screwdriver option during installation as the most likely, given the information you have provided.
Bought the bike last week so I don't know what was used before but I did use tire spoon to take it off myself. Forgot to mention but about a foot from the puncture, the tube was stuck to the tire for about 6 inches as if adhesive was used. When I unstuck it, nothing particular could be seen on the inside of the tire or on the tube. Weird. By running my finger along the tape, I couldn't find any mis-located rim tape. The current rim tape is green in color, very similar to masking tape but seems thicker. Is that line that runs across the tube on the right of the puncture normal?

Yeah, I blow out would have sucked, specially when I was going downhill at 40+ km/h... It was the rear wheel, which I assume isn't as bad as a front tire blowout?

Originally Posted by Berg417448 View Post
Any bike shop will have it or you could order the tape on line. Its just tape with adhesive backing. forward video to 1:10.


https://youtu.be/DFM96d_Fc6g?t=1m9s
Ok thanks. I'll check tomorrow after work at my local bike shop.
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Old 04-11-17, 04:47 PM
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I looked at the tube again and noticed that it's a 700X23/25C. My tires are 700x35. Could this have caused that pinhole on the rim side? Now I guess I'll have to remove the other one and see if it's the same...
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Old 04-11-17, 05:13 PM
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Originally Posted by SylvainG View Post
I looked at the tube again and noticed that it's a 700X23/25C. My tires are 700x35. Could this have caused that pinhole on the rim side? Now I guess I'll have to remove the other one and see if it's the same...
Tubes are able to expand a lot and still work. I've used a tube made for a 26 inch tire in a 29er tire before and it worked fine. I'm pretty sure I've used a 700 X 23/25 tube in a 700 X 35 tire before since it was all I had at the time.
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Old 04-11-17, 05:54 PM
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Sigh, I was hoping I found the cause. I looked for another hole aligned and couldn't find one. Can it still be a pinched tube with just one hole?
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