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Old 06-09-05, 12:56 AM   #1
TheRCF
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Flat mystery

I have had an awful streak of flats. After going about 575 miles and then 450 miles on my rear tire between flats (Conti 4-Season), I had flats after addional 17, 16, 31, and 17 miles. So ,counting the second flat which started the streak, that is 5 flats. Also, all the flats are close, though not exactly, in the same spot.

For example, my last tube had three of the flats. After patching the first time, the next flat in it had the puncture just a hair outside the area covered by the first patch. And then the third puncture was just a hair outside the area covered by the second patch - so the total distance from the first hole to the last is a bit over an inch. Yet I am very careful to line the tire up the same spot each time, so I thought that difference would mean it isn't something left in the tire (the holes are not where the rim contacts the tire so that isn't the problem). Yet what are the odds of getting flats in such a narrow area 5 times and in such short distances?

I have examine the tire carefully each time, looking for anything causing a problem (flexing it every which way). Today I even had the shop give it a going over.

There is a hole in the tire from the first flat from glass, but it is pretty small and while the cut goes through, you can't see it on the inside unless you flex the tire just right. I've had far bigger cuts without having problems and the shop people felt it should be fine as well.

Don't know if it matters, but the last 3 flats have been very slow leaks. For example, today I noted the tire was a little soft (I had to squeeze it to tell). I rode to my destination a mile away. The bike then sat for about 5 hours and felt the same afterwards. THen I rode a few miles to the shop. Pressure on their pump showed it had dropped down to 85 lbs.

We pumped the tube way up trying to find the leak and couldn't - not even when I tried to pull it (to stretch) in the area where I suspected the leak was. I only found the leak when I repeated this at home and put it in water. Even then, I only got a bubble every few seconds. The prior flat was just as hard to find.

I can't think of what else to check. I hate to trash the tire when it still looks fine since it is a $50+ tire!

Bob
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Old 06-09-05, 01:38 AM   #2
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I've had a couple of spells like that, and on both occasions it turned out to be a piece of glass buried deep into outer tyre. When inflated it would press against the tube, causing a slow leak. When I took off the outer tyre I could not find the hole on the inside surface. I could spot the hole on the outside, and after looking very carefully in there, locate a small shrapnel of glass. Last time I had to use a bright LED light to find it, and some small pliers to get it out.

I suggest you take one last look at that tyre, and if you still cannot find the reason, just replace it to cut your losses.

--J
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Old 06-09-05, 01:46 AM   #3
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Quote:
Originally Posted by Juha
I've had a couple of spells like that, and on both occasions it turned out to be a piece of glass buried deep into outer tyre. When inflated it would press against the tube, causing a slow leak. When I took off the outer tyre I could not find the hole on the inside surface. I could spot the hole on the outside, and after looking very carefully in there, locate a small shrapnel of glass. Last time I had to use a bright LED light to find it, and some small pliers to get it out.

I suggest you take one last look at that tyre, and if you still cannot find the reason, just replace it to cut your losses.

--J
I've had the same situation, which is why I did a lot of twisting an flexing. I also probed in the hole left by the first flat, looking for glass. Nothing.

I also don't know why they would be so close together yet be too far apart to seem to be from one specific cause - unless there actually can be some variation even when you line the tire up the same way each time. Let's see, I can't say exactly where all the flats were, other than the three in this specific tube. They cover an inch or a bit more. So the center point would be about a half inch from the two extremes. Can a tube vary that much? I wouldn't think it would vary at all, but maybe so.
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Old 06-09-05, 04:22 AM   #4
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I too suspect that you have something buried in your tire.

Sooner or later, you are going to have to buy a new tire. I'd buy a new one now but save the old tire. Mark the approximate place where the flats are occuring. If replacing the tire causes you to stop getting flats, you can be pretty sure that you have something in your old tire. Now all that you have to do is to find it.

Good luck.
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Old 06-09-05, 02:25 PM   #5
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One of the more irritating items that causes such flats are little pieces of steel-core from worn auto tires. Tiny little pieces of stiff wire that can be very hard to spot.
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Old 06-09-05, 02:47 PM   #6
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Bikewer beat me to it. Slow leak hard to find. I've picked up steel belt from a car. I've had it happen three times. All 3 times it was hard to find. The most striking happened on a long ride. Tire went flat, could not even find the leak in the tube at first (Got lucky a store let me use a sink in back, with total immersion I found the leak). Checked the tire and found nothing. Replaced the tube. Pumped it up. Rode about 50 miles no problem. Put my bike in the back of the car at the end of the ride. Came out next morning and the tire was flat.

Took a good half hour to find the piece of steel belt, which may have been in the tube for a long time. I'm convinced the original flat happened when going over train tracks about 2 miles before the store (which was a schedules rest stop). This drove the belt through just enough to create a slow leak. But once off the track the steel belt slipped back into the tire, leaving nothing to see or feel.
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Old 06-09-05, 03:38 PM   #7
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Well, I checked the tire again - it was up to full pressure from yesterday so the 15 mile trip home didn't damage it - yet. I took the tire completely off, and examined the whole thing as carefully as I could, especially in the area where the flats have been. Even took it into a dark room with a flashlight to see if I could catch something reflecting and also probed the existing holes with a dental pik to see if something hard was in there.

Same result as always - nothing. Well, we'll se what happens on my ride tomorrow. Since this problem started, I haven't gone over 31 miles without a flat. I have 15 so far this time and my normal ride is a minimum of 26 and usually 30. If I get through tomorrow, that will be a good sign, though not conclusive since I would still be at a loss to explain what caused 5 flats in such a limited area.
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Old 06-09-05, 03:44 PM   #8
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If you get another flat examine the area of the tire that you suspect with a very strong magnifying glass. It must be something very small.
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Old 06-09-05, 03:51 PM   #9
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I'll have to get a magnifying glass. I haven't put the tire back on yet and I do have to go shopping. If I happen to see a magnifying glass, I'll check it today.

The only other possibility - other than an astounding set of coincidences - would be a previous hole damage wearing a hole in tubes. I've had that happen, but always with much bigger holes. Like I said, I have to really flex the tire a lot to even find the hole on the inside. Also, when this problem does happen, I expect to see rub marks around the hole, but I haven't seen any of that.
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Old 06-09-05, 07:33 PM   #10
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Checked with the magnifying glass - still nothing.
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Old 06-10-05, 04:41 PM   #11
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Well, for what its worth, I put in 35 miles and no flat (unless there is a slow leak again that shows up later). That's the furthest I've managed since the streak started and usually I only managed 15-17 miles.

I won't feel even a little bit safe unless I get to at least 60 miles - but if the streak suddenly stops, that would be another mystery!

Bob
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