Tubeless puncture... Now what?

[Kevin T]

I've been running Schwalbe One tubeless tyres on my road bike for about a year and have been generally impressed.

Apart from one occasion, I was as to get home without any need to remove the tyre.

I wondered however if there's any advice about the most effective way to get a puncture to seal up properly at the side of the road.

I tend to pump up with co2, spin the wheel a bit and go on my way. Usually this means I'm stopping a good few times for a top up before it's truly sealed enough at a decent pressure.

Is there a trick to getting it to seal at a decent psi first time?

 

[Yellow Saddle]

I assume there is sealant in there? The trick is to put only the minimum pressure in first time and then roll the wheel so that the puncture is at the bottom. Drop the bike's front a few time (bump it) and it should seal.

Caution: If you have a latex-based sealant in there (milky white stuff), it is not compatible with CO2. The CO2 will cause the latex to congeal into a clump, yet leave the inert water to slosh around inside, giving you the impression that there is sealant in there. If you had inflated your wheel way back with CO2, the stuff inside your tyre isn't sealant anymore.

 

[Kevin T]

Interesting. I didn't originally inflate the tyre with co2 but clearly have added co2 now to seal. So you're saying I have now rendered the remaining sealent useless?

Good tip about the tapping

 

[Kevin T]

Reading elsewhere that if you use co2 with the valve at the top (and obviously the sealent at the bottom) it mitigates the risk of the sealent clumping. I must say when I've had to patch my tyre in the past and changed sealent, both times have been after a co2 roadside recovery job and I don't remember the sealent going lumpy when I've got rid of it

 

[screenman]

Some sealants are compatible though, so check it out.

 

[Kevin T]

Pretty sure I'm on Stans Latex

 

[Yellow Saddle]

Reading elsewhere that if you use co2 with the valve at the top (and obviously the sealent at the bottom) it mitigates the risk of the sealent clumping. I must say when I've had to patch my tyre in the past and changed sealent, both times have been after a co2 roadside recovery job and I don't remember the sealent going lumpy when I've got rid of it

That remedy incorrectly surmises that the clumping is due to the CO2 freezing the liquid. It is not. The Latex is in an emulsion that contains ammonia solution. Since latex is vegetable juice, it rots easily and the ammonia sterilizes and protects the latex from rot. The Co2 readily dissolves into the solution and acidifies it. Once the solution is acidic, it can no longer keep the latex in the emulsion and it "Crashes" out, meaning clumps together and congeals. Temperature has nothing to do with it.

There are many different types of sealant on the market but they seem to be either latex-based or glycol based. The latter is thickened with rubber and/or paper/sawdust particles and it blocks the hole rather than seals and bonds it with glue. Latex also requires a blocker, usually rubber crumbs. This blocks the hole and helps the latex that escapes with the first squirt, to become trapped and congealed.

On mountain bikes with wide tyre cavities, the congealed latex looks like a crazy sea creature. I dubbed it "Stan's Coral." Look at the picture to get an idea of the size. If you inflate the tyre you can easily feel the ball inside. It is quite hard. I haven't seen this happen on roadbike wheels but just because my customers didn't use sealant in their skinny tyres. It may well be that a RB coral is so small that it isn't noticeable.

"Coral" from three different brands of latex sealant. All due to CO2 inflation.

 

[Kevin T]

Is this reaction instant or does it happen over time. Now home, I have released the co2 from the valve and intended to re-inflate with a track pump. Unfortunately, I let too much out and the tyre has unseated. I don't rate my chances of getting it back on without a compressor now. The tyre is due for replacement anyway, so I will simply do that and will report on any clumps!

 

[Kevin T]

There was a big clump when I removed the tyre. But that was after a good hour or two with the tyre sitting there in the rim but not seated. What actually causes it to harden in a cut? Is it exposure to lower pressure air?