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I have a road bike with tubeless tires (700x25) and I have noticed for a couple of rides now that by the end of the ride I lost quite a bit of pressure.

To check out what is going on, I re-inflated to 100 PSI and realized that air was leaking out from a puncture after a couple of minutes. It would appear, however, that the sealant closes the puncture off after I have lost some pressure.

If I inflate it again to normal pressure, the same behavior is repeated.

Would this indicate that I may have a foreign object inside the tire? Should I use a repair kit on that puncture that appear to be very small since the leak appears to stop on its own every time?

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  • Perhaps try a sealant with more solids/fibres in the content to block the hole
    – Noise
    Jul 1, 2022 at 17:09
  • I am using Stan's notube, injecting an extra 20ml did not help sadly
    – icykof
    Jul 1, 2022 at 20:34
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    Standard Stan's doesn't have a particularly good reputation for the higher pressures used in road tubeless. You might want to consider either the 'race' version or a different brand.
    – Andy P
    Jul 2, 2022 at 22:34
  • thanks, I realize I do have the standard version
    – icykof
    Jul 3, 2022 at 13:10
  • The “race” version of Stan’s works great, but it does have its drawbacks. Is is so good that it is more prone to eventually plug valve stems as well. This is based on second-hand experience from a number of my riding friends and bike shop mechanics and owners that have experimented with it. If one is racing a race they have worked all year for, then it has a place as a guarantee against a flat. Also, in an emergency when you are stranded and it is all you have. It is just not recommended for day-to-day use by the riders I ride and race with. Too much of a hassle.
    – Ted Hohl
    Jul 3, 2022 at 14:30

2 Answers 2

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Road Tubeless. Sometimes they seal up, sometimes they don't.

Early in my road tubeless adventures, I let the sealant just do its job. It took about 15 minutes to really get the seal good enough to ride it again. If you don't wait long enough, the "plug" that the sealant makes breaks up and you need to start the 15-minute clock again. This applies to glass cuts and such. I have some rounded thorns in my area (tackweed/goatheads/puncture-vine) and the rounded thorns leave a nice, round, small hole that seals much quicker than 15 minutes.

Sometimes, even 15 minutes is not enough. If I have a stubborn hole that just won't seal, or I am in a hurry and don't want to wait 15 minutes, I use a tubeless plug. These consist of a plug that is inserted into the hole in the tire, which along with the sealant seals up the hole very nicely and quickly, and usually without much air loss.

Here are the two plug types that I carry on every road ride:

The first is a product by Genuine Innovations. It is a repair kit and uses "bacon strips" (their name) as plugs. Simply insert a tacky bacon strip into the fork-like insertion tool, shove it into the hole, leaving some of the bacon strip exposed outside of the tire, and ride on. In the "kit" includes a couple of extra valve cores and one end of storage container has a presta valve core removal tool.

Genuine Innovations repair kit

The second and more expensive is called Dynaplug. They were originally used for car and motorcycle applications, but they have developed a system for bicycles that are tested in some demanding (gravel and MTB race) conditions.

Dynaplug Pill repair kit

In either of these tools, be sure not to push in so far that you tear up/puncture the rim tape on your wheel.

If you do remove the tire, the hole/puncture can also/instead be patched with a traditional patch kit for a tube. You will need to clean up the area where the patch is applied, of course. However, DO NOT use the sandpaper to roughen up the inside of the tire (like you would do to get a clean area to apply a patch on a tube). The reason is because if you do, you will likely tear up the cords on the tire, which will weaken it (I did this once - NEVER AGAIN!). Once the patching is done, you would have to remount and seal up the tire again.

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    ok so I guess I got into a situation where for some reason the sealant can't properly close off the puncture (at millimeter level from what I can see or even smaller). I will try the plug repair kit. thank you!
    – icykof
    Jul 2, 2022 at 7:26
  • @icykof - they take a bit of practice to get right, but with one of these kits you are prepared for the inevitable puncture. Read up on them a bit, and if there are videos of their use, take advantage of them to get a feel for how to go about a repair. It truly is "on-the-job" training. The Genuine Innovations (GI) product is the one I have the most experience with. The GI bacon strip is inserted into the fork by its end and pulled to center it. Then the folded bacon is shoved into the hole, leaving the two ends exposed. Use a thumb to hold the exposed bacon in place while removing the fork.
    – Ted Hohl
    Jul 2, 2022 at 17:08
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    turns out for my puncture, the sealant ended up doing the job after a while and coutless retry at re-inflating the tire
    – icykof
    Jul 3, 2022 at 13:08
  • update: after a few more runs, my tire started to leak again, even after using a denser sealant, so I just changed the tire, which is sad because the puncture really was not big.
    – icykof
    Nov 10, 2022 at 5:04
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Tubeless solution sealing a small leak is normal, but the challenge is doing it with low volume/high pressure tires. With large volume tires for mountain bikes, it is normal for small cuts to seal after some air escapes, and a rider is unlikely to notice the difference even while riding.

The difference here is that a small amount of air in a narrow road tire apparently is causing you to lose 5-10psi.

With tubes, when you are leaking air, there is either a puncture of some size or the valve is leaking; and the fix is to confirm the leak, typically by submerging the tube to find air bubbles, then see if the cause of the puncture, like a thorn, is still there.

Tubeless does not require you to remove thorns because the sealant will seal the puncture. But with higher pressure, possibly that small puncture is leaking too much air before sealing.

Unfortunately, removing the tire for any reason means potentially redoing an entire tubeless setup, including retaping the rim (sometimes the tape peels up when the tire is removed). In any event, I suspect your PSI loss is due to higher pressure and the sealant unable to hold it in, and the fix may be to install a tube.

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  • the leak is done through a puncture that the sealant can close off only if the internal pressure is not too high it seems. Otherwise it looks like the seal does not hold. Unfortunately I lose much more than 5-10 PSI, and this is when I'm not riding the bike. When I ride it is much worse :(
    – icykof
    Jul 1, 2022 at 20:12

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