Tubeless woes

I've never tried tubeless and I don't intend to. The reason is if you're plagued with flats, I'd suggest that the best way to go is TPU tubes with alloy valve stems in a Continental 4 seasons tyre. You'll get that feel of tubeless and far less chance of punctures. I have 25mm tyres. I've also got some latex tubes to try when I get around to it. The tubeless sticky mess set up puts me off tubeless. 

I recently added Mariposa Vitamina CL (a powder) to my tubeless sealant. The difference is amazing, the tires hold pressure far better than before, just like a tube. (Of course, that begs the question, why is this powder not already added to the sealant by the manufacturer ?)

High (road) pressures, small volumes and liquids do not work for me. I've gone to TPU tubes with non tubeless ready tyres. Brilliant.

About four years ago I was also at a loss Mr Grumpy, and for the same reason.  My "Covid" bike build had been a great success with everything performing well and when the first lockdown ended I set off on a three-hundred mile tour.  The first half-an-hour went swimmingly but then a tiny pinprick of a puncture completely defeated the Stan's sealant and I was forced to put a tube in the front tyre.

A fortnight later the rear tyre collected a 4 - 5mm gash and the Stan's couldn't cope with that either.  At this point I deduced that, to suit this particular sealant, punctures have to be exactly 2.66mm in diameter, perfectly circular, precisely in the centre of the contact patch and it must be the third Friday in the month.

I went back to tubes the same day and have had perhaps three flats since.  I won't get burned again.

Hey Mr Grumpy. 

I'd say from my experience, this is just bad luck on sealants. Not all sealants are the same. I run 23/25/28mm tyres at 80ish PSI and have been tubeless since schwable annouced their Pro-Ones years and years ago, I had a pair off a rep before they were in the shops. Anyway, I've made all the mistakes, I now use (and have done for years) two brands which I know work 1) Effetto Mariposa Caffelatex Sealant  and 2) Bontrager TLR Sealant. 

The only thing I absolutley do make sure I do before using is shake the hell out of the bottles as the bits of stuff that fill the holes will get attached to the bottom of the bottles. 

Both are injected through the valve (but I do not use the very thin tubes which can come with syringes as the bits of stuff that fill the holes can often not go through. I use a bit of clear PVC tubing (approx 5 or 6mm) which goes over the presta valve as opposed to in it (cleaner and easier to squirt it in that way also). 

Never been convinced of narrow tyres and high pressures for tubeless. Wider tyres, lower pressures is best.

I've had no problems with GP5000s and Caffélatex sealant, although I do find that the sealant needs topping up every few months to replace any that's dried.

I have had a couple of tricky punctures where there was some glass or debris still stuck in the tyre. It'd seal whilst riding, but would then make itself known when pumping the tyre up to over 70psi, but then seal again with a little persuasion such as spinning the wheel.

I've had some similar experiences to yourself with road tubeless - first tried in 2018 with Mavic's (new at the time) road UST, it was useless, had 3 unsealed punctures in 4 rides, after running (Stans) tubeless on much lower pressures successfully on MTB & gravel bikes. I concluded it was a combination of trying different sealants (Mavic, Orange & Muc-Off) not sealing on 25mm tyres at 95psi in the wet. Plus Mavic tyres seem to get cuts if you even look at them. Went back to tubes at the time on the winter bikes. 

Forward to 2022, I put tubeless again on a winter bike (Hunt 4 Seasons and Schwalbe G-One Speed 30mm at 65psi) and it seems so much better. Get a fair bit of weeping and a lot of sealed holes but minimal pressure loss, and now on a summer bike which I've put Roval CLII on with Conti GP5000S-TR, 30mm front, 28mm back at 70psi, it's been absolutely fine. 

My conclusion is that road tubeless, in my experience, works best with lower pressures, and with Stans fluid, with some Stans Darts in my jersey pocket (not used yet). The higher pressure just doesn't seal in time with the lower volume, particularly in the wet. I asked a mechanic in the LBS what sealant they personally used out of the 6+ they sell, he replied "we all use Stans at lower pressures"

Anyway, good luck!

Also I should add (from personal experience) that when following andystow's advice on a thorough shake, always make sure the lid is on properly.

Are you shaking your sealant before adding it? At least a minute of vigorous shaking?

How old are your tyres?

Just some ideas... to me it sounds like it might be a case of Murphy's law!

I know many people think tubeless is not worth the pain for road, I guess they just had these issues sooner... I mean, sealant dealers wouldn't make it more fluid than 10 years ago to sell more? and tubes won't help to prevent flats anyway...

I'm thinking 80 psi is not a lot for 25mm, if you lose some pressure while riding it might get even lower, then every small pothole will "pinch" the tyre. Although it's less common with tubeless I know it can happen too, and could fragilize the tyre? Advised pressure vary a lot if you follow the indications on the tyres, wheels, or are using these online calculators (usually these indicate the lowest pressure, at least in my case). Now I'm sticking with the highest minimum, which is the numbers on the tyres, for my equipment.

Or maybe you are using an old batch of tyres? Obviously not all tyres are equal, now I'm chosing mine to prevent flats, not to gain a few km/h, I'm using Pirelli Cinturato Velo, on roads and a few trails. Gators have also a good reputation for puncture resistance. Of course they are almost 50% heavier and much slower than these GP's or fast Vittoria's (I'm not into racing) but they have a good grip... only issue so far, they are ~2mm wider than announced, both 26 and 28 mm, on 19c and 22c rims.