Fun With Tubeless Tires: Left High & Dry

When all else fails…

A week or so ago I went for a ride in the rain. I didn’t care that it was raining: I wanted to go for a ride and Fulgaz wasn’t going to do it for me. I took the bike with the tubeless tires this time because in the two previous outings I didn’t and guess what? I got flats. In the rain. Do you know how irritating it is to change a tube when it’s raining hard? Oh, and good luck finding the cause of your flat before putting in a fresh tube to get home. When your hands are cold and everything is soaked and covered in dirt, it’s harder to feel for that piece of glass, wire, or flint stuck in your tire. For one of the flats I ended up calling for a rescue to get home since I flatted the spare as well when I didn’t find the cause of the flat and just stuffed the new tube in. (Long story: I actually did find a wire and a piece of glass stuck in the tire and removed them. But it was a yet another glass shard that caused the flat!)

This was no epic ride, just a short jaunt out the local bike path and back. No problem, right? Nope. After the turnaround and while standing going up a slight incline, the rear wheel felt a bit bouncy. But I discounted it since I couldn’t have a puncture because I had tubeless tires! A couple miles later it was obvious I had punctured because the tire was very low. I was able to pull out of the rain under a gas station canopy to try to pump up the deflating tire. There was no use in trying to find the source of the problem because I had fenders that prevented me from inspecting the tire carefully, for what was obviously a slow leak, and anyway everything was filthy and wet. Would I even be able to see the offender? I doubt it. My minipump has a gauge and it said I had about 10-15 lbs. pressure. So a hundred pumps on my minipump and a prayer later the tire still wasn’t hard but good enough for me to get further down the road where I suspected I’d have to stop and add more air. Fortunately one of the local churches down the road had installed a self-standing bike repair station with a floor pump. I pulled in and used it to get the tire up to 60 lbs. I was able to get home without another stop, which was a good thing because it was raining hard.

Per routine I dumped the bike in the shop to be dealt with later. The next day I was able to give it a proper inspection and I found the puncture: it was a sharp, tetrahedral-shaped flint. Being about 3 mm. in size the rock was easy to spot. Interestingly there was no sealant around the intruder. Immediately after popping the sharp stone out, the tire deflated with a rapid hiss. No sealant spewed out. A probe inserted into the valve stem came out dry. Well, that answers that: even though I had topped off the tire about three or four months ago, all the sealant had dried up.

How could the sealant, Orange Seal Endurance, have dried up so quickly? This tire was relatively new and unlike its predecessor it has always lost air through time. This is likely due to a very slight difference in the rim-tire bead interface. There is variation in tire production and all it takes is a minute difference in thickness, uniformity, or diameter and the tire bead may not seat perfectly against the rim. Another possible reason is that despite having cleaned the rim carefully before setting up the new tire I may have missed a bit of old, dried sealant that would have created a gap. That slight difference is enough to leak air slowly. Even though I always had to pump this one up before a ride, it was no more hassle than with latex inner tubes or sewup tires so I didn’t give it too much thought. And the prospect of demounting the tire and cleaning everything over again was too daunting even for someone as anal as I.

Apparently over time the less than ideal seal had allowed the sealant to evaporate more quickly, something that hadn’t occurred to me.

There is a preventative solution, a solution that I knew about but didn’t apply when I set up the tire because I hadn’t confronted this problem before and it thus seemed completely superfluous. After filling the tire with sealant I should have sloshed it around thoroughly so that the sealant flowed around both tire beads. This involves tipping and rolling the wheel every which way to make sure the sealant is distributed throughout the interior of the tire. Then it would seal any tiny gaps at the rim-tire bead interface. Here’s a link to one way to do this.

With this repair I mistakenly thought that all I had to do is add sealant and the hole would vanish, voila! But after adding sealant and pumping the tire, air and sealant spewed endlessly until the tire was almost flat again. A second try had the same ending. I had a hard time believing this was happening: this hole was barely 3-4 mm. long and Orange Seal should have closed it off. But it wouldn’t. So out came the tubeless repair kit. This was the same Genuine Innovations kit I used the last time. And I had the same frustrating experience as before: I just couldn’t get the damn tire plug to go into the hole. By the way, most tubeless repair kits have the same shaped plug tool: it looks like a very tiny two-prong spear. The idea is that the tire plug can somehow be placed between the prongs so that it’s held in place when you jam the thing into the rubber tire and then it releases it. However I’ve never been able to get the plug to fit the prongs. No way José. This is why Dynaplug has become such a hit: there is no prong. Instead the tire plug is capped with a metal spear point that you just mount in the stick tool like an arrowhead and then plung into the hole. When you withdraw the tool, the plug releases easily since it’s not held by any prongs. Besides being ridiculously expensive, Dynaplug has another problem: those metal tips are sharp, deliberately in order to go easily into your puncture. But if you end up having a flat that won’t seal and can’t be replaced with a tire plug, you either put in a spare tube or call for a rescue pickup. But that metal tip now lives in your tire and can puncture any tube that is ever inserted in the future. Basically when you switch to Dynaplugs you can’t go back to tubes without pulling out every one of the plugs first. So I don’t use Dynaplugs.

Sharper than a serpent’s tooth…

As before I ended up just holding the plug against the puncture and jamming it in with a tiny flathead screwdriver and then pumped it up. No leak. And this time I put in so much sealant that for the first time ever I could hear it slosh around as I spun the tire. Oh, and after swirling the wheel every which way for some time, I did notice sealant bubbling out at the rim and eventually sealing. After sitting overnight the tire held air.

By the way, while inspecting this tire after fixing the flat I saw what I thought was a speck of dried sealant on the tread. But it wasn’t: it was the base of a tiny thorn. I popped it out, sealant bubbled out, and it sealed. So although this cautionary tale might seem like I’m yet again kvetching about tubeless road tires, you have to remember that the value of all things is relative: what do you have to endure with the alternatives? In this case I flatted in the rain but it could have been worse: I would have replaced a flatted tube with a spare after finding the flint but then punctured again with the thorn. At least with tubeless I made it home.

If your tubeless road tires regularly lose air, you may inadvertently be drying out your tire sealant at an accelerated rate. So after topping off your tire with abundant sealant, make sure you do the Jan Heine wave to distribute that sealant completely in the tire to seal any tiny gaps and holes.