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[UPDATED] The Mystery of a non-punctured Flat Tire
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I race on Tubular Zipp 808. First time I bought it in 2012 it had Vittoria Corsa on it. Raced it at a 70.3, had a solid race, loved the wheel and when the time came to put the bike back on a car rack found out that the tire was flat. Thinking that the tire was punctured I stripped it off and installed a Conti Competition tubular, which has been a champ for 5 years until I blew it out by hopping over a metal rod.

I wanted to go to latex so in 2017 I got a 28mm Zipp Speed SL. Filled it up with Orange Seal. Had a few races on it without problems, then at IM TX 2018 (yes, THAT IMTX) I flatted with about 6 miles to go. Did not see any debris in the tire, filled it up with C02 and it held for the remaining 6 miles (albeit it was half deflated by the time I rolled into transition). I did not see any orange seal coming out so wasn't quite sure where the leak was coming from. Sent the bike back home through TBT, picked it up, pumped up the tire ... and it was good as new. I literally went for a 60 minute ride with it without a problem and it did not have any leaks above and beyond what you'd expect from latex (~10-20 psi/day).

Not wanting to get another flat in a race i bought another 28mm Zipp Speed SL and threw the old one out. Raced a few more races in 2018 without a problem. Fast forward to 2019. Did a 30K TT 3 weeks ago, had a great race - no punctures, put the tire back on a car rack ... flat again. No sign of Orange seal either. It's been laying around for 3 weeks, somewhat flacid (10-20psi) but did not go fully flat. Just pumped it up to 120 and its holding fine.

I check the tires religiously before every race and other than few small shallow cuts on the outside there is no indication of puncture. I also glue them myself and clean the rim before installing (no debris there). Finally my front 24mm Zipp Speed SL has been working with no issues since 2017.

Sooo .... what's up with that? Love the set-up, but flat/non-punctured tires are a bit of a head scratcher. Has anyone else experienced this and what was your solution?
Last edited by: Anton84: Jun 25, 19 18:12
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Re: The Mystery of a non-punctured Flat Tire [Anton84] [ In reply to ]
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Any issue with the valve interfaces?
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Re: The Mystery of a non-punctured Flat Tire [Nonojohn] [ In reply to ]
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x2. My guess is either valve core or valve extender.
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Re: The Mystery of a non-punctured Flat Tire [Anton84] [ In reply to ]
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Did you put them underwater to find a leak? Sometimes that's the only way I find them.
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Re: The Mystery of a non-punctured Flat Tire [trail] [ In reply to ]
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Same thing happened to me with my Corsa Speed tub. It went slowly flat during a race and was virtually flat when I rolled into T2. I pumped it up when I got home, curious to see where the hole was and it didn't go down. I rode for 2 hours on it and it was fine. I can only think that there was air seeping out of the core valve.
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Re: The Mystery of a non-punctured Flat Tire [jaretj] [ In reply to ]
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Update: did a 40k TT this weekend (rode 56:11, thank you very much), 100 yards after finishing I got a flat tire (Good timing, right?).

Tonight I pumped it back up and noticed that instead of holding air, it’s slowly going flat. I put it in water and here is what I got:



Air leaking out of porous sidewall. Both sides of the tire. Most pronounced on the side opposite of the valve, but get bubbles around a pretty wide area. Inspected the tire, and again found no cuts on the outside. Suspecting that something is wrong with the inner tube around that area.

Have no idea how this has been happening repeatedly AFTER my races have been done.

Unless folks have some clever ideas the tire is going into garbage, and $100 is going out the window.
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Re: [UPDATED] The Mystery of a non-punctured Flat Tire [Anton84] [ In reply to ]
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There are a few things that you mention that reminds me of my flats due to the wheels rim "tape" band that covers the spoke holes. It was a solid fiberglass(?) band that came with the wheels.

My flats would come after some use. Flats would occur when I hit bumps, etc but were not pinch flats. Tire would go flat over night.

The band had such a small "sliver" of imperfection that I dismissed it as the cause. Once I switched to cloth tape, it stopped happening.

Indoor Triathlete - I thought I was right, until I realized I was wrong.
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Re: [IT] [ In reply to ]
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Tubular tires?
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Re: [IT] [ In reply to ]
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IT wrote:
There are a few things that you mention that reminds me of my flats due to the wheels rim "tape" band that covers the spoke holes. It was a solid fiberglass(?) band that came with the wheels.

My flats would come after some use. Flats would occur when I hit bumps, etc but were not pinch flats. Tire would go flat over night.

The band had such a small "sliver" of imperfection that I dismissed it as the cause. Once I switched to cloth tape, it stopped happening.

Back in the early 90s I had a run of flats that always happened on the drive home from a race. I'd get through the race with no problems, put my bike on the roof rack and put the front wheel in the hatch, and halfway home I'd hear "Pssssssssssssss....". This would happen after every single race. Turned out that the issue was the urethane rim strips I was using. Sitting in the back of the car under the glass hatch, the wheel would get warm enough that the rim strip would soften up, and the tube would push it through the spoke holes until the tube expanded enough to pop. Without any air pressure, the strip would return to its original shape. I finally figured this out when the rim strip burst along with the tube. I switched to Velox and it never happened again...

"I'm thinking of a number between 1 and 10, and I don't know why!"
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Re: [UPDATED] The Mystery of a non-punctured Flat Tire [Anton84] [ In reply to ]
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SOLVED:
I cut open the tire to inspect the tube. There was a small, slightly deformed area which I suspect formed because of a kink in the tire (likely from being folded when it was sold, because I kept it mounted on the wheel this entire time). The area had a small hole which was leaking air into the tire, which was releasing air through porous sidewalls. I suspect the Orange Seal has partially blocked the hole, for a while.

My overall feeling is that latex tires are pretty frigging fragile, and are likely to have some sort of flat issue eventually. This one was 2yrs old.
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