Punctures

Nebulous

Veteran
Location
Aberdeen
I got new wheels on Thursday and had to set them up for an audax on Friday with very little time for testing. New tyre on the back and part-worn one on the front, both 28 mm gp 4000s. Wheels didn't have a hole in the rim tape, so I poked the valve through.

Middle of the night I had a puncture on the front. Get about another 80k and discover tyre is very soft, so change tube again. Another 20k tyre is again very soft. I convince myself it must be the hole in the rim tape with an edge rubbing against the tube. Visit a bike shop, where he locates hole in tube, finds a corresponding tiny piece of wire in the tyre and removes it with a pair of pliers. He gives me a new tube with sealant and sends me on my way. He says the rim tape hole is fine.

I get another 150k this time and hear a strange noise after going through a puddle. Stop, tyre is still hard, continue, short distance later hear it again, and then again and this time tyre is flat. By this time I'm out of tubes - remove tyre and halfways round there is a very small hole in the tyre, possibly where the wire was previously. Near it there is liquid sealant in the tyre. Another guy on the audax passing gives me a park tools emergency tyre boot, a thin piece of sticky-backed plastic card which goes over the hole in the inside, put back on the sealant-filled tyre, blow it up and fortunately it stays to get me to finish the event.

So what do you think I'm up against? Would a small, less than 2mm hole be enough for a tube to protrude and burst? Possibly multiple times from the noise I heard?

I'll replace the tyre, but I've been inclined to blame the wheels - particularly as they are new. I'm not home yet, but will do a soak test on the two old tubes to locate the holes.
 

I like Skol

Hold my beer and watch this....
Think about it logically!

You put a used tyre on the front and it went down during the night. You then replaced tube in a rush and tyre again (twice) went soft during your event. You take it to a shop who does the proper investigation and finds a piece of wire in the tyre. This was most likely there all along and caused all the flats so far.

You then get a puncture during the rest of your (long distance) ride. This would not be statistically unusual, except now you suspect your wheel is faulty?

IMO, you have had two punctures, one was present in the used tyre before you fitted it to the new wheels so occurred the last time the tyre was previously used, the second puncture occurred during your long distance audax.

Examine the wheel by all means, but I would expect there is nothing wrong with your wheel or rim tape. ***Find the cause of your last puncture***
 

Ajax Bay

Veteran
Location
East Devon
You must find the source of the puncture before (just) inserting a new tube. Care lining up the tyre logo with the valve and paying attention when removing the tube as to orientation helps, in fact I leave the inner tube valve in place and give it a pump to see whether I can detect air egress (using lips or cheek as the sensitive detector).
And if that takes time, it's a lot less time than stopping further down the road with a repeat offense.
I carry a safety pin to poke out bits of wire like yours - they're often very difficult to get out once you find them. If I have to use a second tube (on a second deflation) I also patch at least one of the two punctured tubes - so carry a little square of sandpaper and some self-adhesive patches.
For a ride where finishing is really important, I carry a spare tyre (an old one that I've replaced before its full life). That way, if one "can't" find the puncture cause, use the spare tyre (and a fresh inner) until a control or cafe stop where you can examine the original tyre at leisure (and find the puncture cause.
Punctures caused by penetration will be on the 'outside' part of the inner tube. One caused by rim tape slippage and the edge of a drilled spoke hole, or a snake bite, will be on the 'inside'.
Brevet Cymru 400 at the weekend.
 

Globalti

Legendary Member
I've had a few annoying mystery punctures in the course of my life as a cyclist and they have all been caused by tiny pieces of glass lodged in the tyre. If you examine the tyre carefully, probing any holes with a needle I bet you will feel it grating on something stuck in one of the holes.

A 2mm hole will allow a latex inner to herniate and burst with a rude squeak but a butyl tube is stiffer and will bridge the hole.
 
OP
N

Nebulous

Veteran
Location
Aberdeen
What did you find?
Small pin hole in the two tubes I changed and kept. As expected really to match the piece of wire the bike shop man removed. Small pin hole with sealant in it where the hole in the tyre is. I couldn't find any other objects in the tyre, now I've examined it in the dry with a decent light and glasses on! I'm convinced the park tools emergency tyre boot was what got me over the line. Tyre has been thrown out and I've bought a new one, 5 new tubes and some Park Tools emergency tyre boots for myself. Small hole in the tyre shown. The neat round hole is the continental wear indicator, but it helps to give scale for the hole.
IMG_20190503_143658173.jpg
IMG_20190503_143815652.jpg
 

silva

Well-Known Member
Location
Belgium
I've had a few annoying mystery punctures in the course of my life as a cyclist and they have all been caused by tiny pieces of glass lodged in the tyre. If you examine the tyre carefully, probing any holes with a needle I bet you will feel it grating on something stuck in one of the holes.

A 2mm hole will allow a latex inner to herniate and burst with a rude squeak but a butyl tube is stiffer and will bridge the hole.
I can report the same, tiny pieces of glass, every rotation of the tire, the deformation of the part touching the ground, causes those tiny pieces to move a bit, and cut themselves further / deeper in. And in the end, they scratch their way through the tires protection layer.
I learnt to have the discipline when arriving at work, to turn the bike upside down and inspect. Sometimes along the road too, either as a sudden random decision, either because I noticed glass.
And I hold a small very sharp sewing scissors in my bag, to get those glass pieces out, because any common tool is just too big / too damaging to do this without causing further damage to the tire.
Nowadays I fill the holes with a rubber sealant.
Roads are full of tiny pieces glass. If the sun sits low, one can see the blinking everywhere. With an exception - there is some street pavement that contains particles that also blink like that. Probably for cosmetical purposes, but it's crap since one can not rely anymore on blinking to identify glass.
 

Kajjal

Veteran
Location
Wheely World
I had a small piece of glass stuck in one of the nobbles on my mountain bike. As above found it by lining up the inner tube and then flexing the tyre a lot to see what was going on.
 

rogerzilla

Legendary Member
This is why you should always line up the tyre logo with the valve when fitting a tyre, Find the hole in the tube, and you can easily find what caused it in the tyre. It's not an OCD thing - it has a practical purpose.
 

Tom B

Über Member
Location
Lancashire
This is why you should always line up the tyre logo with the valve when fitting a tyre, Find the hole in the tube, and you can easily find what caused it in the tyre. It's not an OCD thing - it has a practical purpose.
Or mark the tyre against the valve hole when removing.
 

Tenkaykev

Veteran
Location
Poole
Roads are full of tiny pieces glass. If the sun sits low, one can see the blinking everywhere. With an exception - there is some street pavement that contains particles that also blink like that. Probably for cosmetical purposes, but it's crap since one can not rely anymore on blinking to identify glass.
There are many different types of " Tarmac" used as road / pavement surfaces. Different mixes for different usage. Some mixes add recycled ground glass to make it more hard wearing, that's probably the stuff you notice glittering
 

SkipdiverJohn

Veteran
Location
London
This is why you should always line up the tyre logo with the valve when fitting a tyre, Find the hole in the tube, and you can easily find what caused it in the tyre. It's not an OCD thing - it has a practical purpose.
For many cyclists it is an OCD thing, just like excessive bike washing & polishing. I admit I do have my Schwalbes fitted with the logo centred on the valve, but I don't bother with tyres that don't have a clearly visible logo. If I get a p*ncture on a plain tyre I put a little dot on the sidewall by the valve with a marker pen, to enable me to search for embedded objects in the right area.
 
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