I am a total tubeless convert – just check my posting history! I have no intention of going back to tubes, patches, all that crap.

But… Events like this evening do drive me crazy, wondering if it’s just me.

So – both my MTB and road bike set up tubeless; I ride both regularly, for commuting and fun/training. I top each bike’s wheels up with air approx weekly. I’ll have this routine for months on end, with no troubles or change to routine.

My road bike is my usual commuter bike. I road it yesterday back home, and stuck in the shed afterwards. Woke up this morning ready to ride, and the rear tire was totally flat. No warning on ride home yesterday – no hissing, no potholes hit, etc. This happens about once or twice a year on each bike – I’ll have no warning, no excuses, and the next morning a totally flat tire.

Is it just me?

Does it go back up again?

If so then perhaps someone is playing a trick you…
If not then I guess you have a puncture

Latex gremlin.

only happens to me when sealant needs topping up

The seal between the bead and tyre is probably breaking slightly at a particular spot and occassionally opens up, leaking out the air. Riding prevents it happening because the sealant is moving around to seal it if necessary.

Sealan needs replacing every 3-6 months

I was going to ask the same question actually.

I’m totally new to MTB and tubeless tyres. I bought a new bike in July and its been perfect. However after a few weeks back, coming back from a pretty muddy ride and instead of washing the bike off, like a slob, it got left in the car for 3 or 4 days.

When I finally got it out the bike tyre was totally flat but blew straight back up and stayed up for the next ride. Anyway the exact same thing happened this last week but I am yet to blow it back up.

I thought perhaps the mud was drying on the tyres and maybe breaking the seal?

Yes it seams to happen a lot to me! I have a new canyon (nerve al8) ust tubeless setup tyres/rims. Because they were so light at the start I thought they were already tubeless, got a flat and then realised they had a tube in! 😳
So I set them up using Stan’s no flats sealant, took a bit of doing as I never had a compressor, just a track pump and an extra pair of hands, once they were up I was over the moon with a great sense of achievement! And a smug look over my fellow tubed riders,
The first two weeks I rode it then went back the next morning to a flat. First the front then the back!
This went on and became a good laugh for my fellow riders after telling them the advantages of tubeless! No punctures and all.
I then decided to put another cap of fluid in taking it to 3 caps in each wheel, this seamed to work and I didn’t get a flat for a few weeks. Since then I’ve had about 3/4 flats in total in the morning over the last 3 months.
I think it’s a combination of very thin nobby nic tyres and washing the wheels with a strong brush after a longish ride.
All I do is get the track pump back out and fill with more air 🙂

Only really get yhe mystery flats when I have neglected to top up sealant.

I suppose given the time of year and the fact that it is a road bike the sealant might have been a bit busy plugging holes and cuts…

Sorry for slight hijack, I just tubelessed my first successful set.

Question: I knew that the sealant needed attention every 3-6 months but I understood you added more.
Someone above mentions ‘changing’ the sealant.
I’m not clear how you could actually change it without removing the tyre and scraping it out? Or have I got the wrong end of the stick here?

All-

Seems like the tire was low on sealant – based on a quick “shake and listen” of the wheel. Added more, but annoyingly it wouldn’t inflate – I think all the dried/crusty sealant along one part of the bead has separated, and allowing too much air out (based on all the sealant leaking out when I try to inflate). Lesson learned – keep an eye on topping up my sealant more often.

@vincienup – I normally just top-up the sealant occasionally – although per above, probably not often enough. I don’t think you have to “replace” it, although eventually you get big sealant boogers that rattle around in the tire. I usually only replace sealant when they start annoying me, or when changing tires – generally similar timeframes anyway. And yes – as far as I know you have to unseat at least a portion of the tire to get the old sealant out.