What do you think about the Vittoria Air-Liner Gravel Tubeless Tire Insert?
https://www.vittoria.com/us/air-liner-gravel-vittoria
I know they are intended for gravel bikes, but I wonder if they would be useful in the front (drive) wheel to give added control after a blowout. They say you can even run flat on them for an hour.
So I did a tubeless conversion on my front wheel, including the Vittoria Air-Liner GRAVEL with a 30c tire on a 25mm inside rim with Stan's sealant. It's been trouble-free for a few months and over 1000 mi. Then I finally got a flat last week.
At first all I noticed was a change in road noise. I bounced the bike up and down to check for a flat, and the rims didn't bottom out, so I continued a few miles to a 7-eleven. There I noticed the tubeless tire was soft, probably <40 psi. It was getting dark, so I booked a motel 5 mi away and put a 16g CO2 in the tire. Some CO2 leaked out, but the tire went up to about 60 psi. When I got to the motel, it was soft again, <40 psi. I was too tired to deal with it that night, but next morning, the tire was almost flat. I took it to the gas station across the road, but couldn't get the tire to seal and hold pressure on the coin-op pump with intermittent pause for pressure measurement. I didn't want to put a tube in it because then I would have to toss the liner.
I assumed the sealant was bad, so I rode almost flat to the bike shop 5 mi away. The ride quality was fine, and the bike was controllable, but the road was smooth and flat, and I kept it under 10mph. You definitely don't want to hit a pothole though.
The bike shop had 2 oz. bottles of Stan's sealant, so I put one in the tire. But when I opened the valve core, some almost clear liquid came out, so the sealer was not lost to leaks or evaporation. They only had a Schrader valve on their compressor, and it didn't work very well, so again, I couldn't get the leak to seal. Due to logistic shortages they were not able to restock any spare tubeless tires after they recently ran out, so that wasn't an option. I had a spare tire at home, so I decided to give up and walk to a train (to save the liner) and then got a ride the rest of the way home. The tire liner made it easier to walk the bike with a flat too.
At home, I was able to get the leak to seal with my compressor. But the tire sidewall had rubbed against something causing a small bubble with a small torn hole in the casing. So the tire was shot, and would not have lasted long if I continued riding as the hole would continue to tear open. I wasn't able to break the bead which was essentially glued on now, and this was complicated by the liner pushing back, so I cut the tire off the rim. Inside the tire the latex in the sealant had rolled up into little rubber cement type balls between the liner and the underside of the tread. I assumed those formed when I rode flat. Also the rim tape was disturbed by my attempts to break the bead and had to be replaced.
So I basically had to start over with a new tire, rim tape and sealant, but I re-used the old liner. I decided to go with a new Conti GP5 TL 28mm tire and their Revo (non-latex) sealer. 28mm is probably the absolute minimum tire size for the 31-40mm rated gravel liner. You can just barely get it under the un-inflated tire, but it needs a lot of encouragement to get the beads in the center groove of the rim so you can mount the tire all the way--the Crankbrothers Speedier Lever is a must. It's a lot easier with a 30mm tire, but that's probably the max for the V20 fork. Vittoria now has a new Air-Liner Road system with 25, 28 and 30mm nominal sizes which work with narrower rims as well.
Bottom line is that I decided to continue using the Vittoria tubeless tire liner. You really can ride it flat, so that is a big safety benefit for front flats. I'm not sure if it would keep the bike controllable on a 40+ mph descent around switchbacks, but it does remove the inevitability of a crash at lower speeds. It also gives you the option of riding to a safer, or shadier, or dryer place to deal with the flat. But then it adds an extra layer of complexity to fixing the flat. I have added a small utility knife, the Crankbrothers Speedier Lever and a small bottle of sealant to my bike based on this experience.
Edit: I think I also need to add a spare tire.
