Another tubeless tire victim came through a while back. He said he'd had the tires mounted at a shop where he lived. The staff there assured him that the process is simple and reliable. A few days later, the rear tire was losing pressure within hours. Now he was away from home, trying to enjoy his trip.
With tubeless tires, the problem never seems to be the simple one you want it to be, like tightening the nut at the base of the valve stem. It's almost always the rim tape. Rim tape is the fatal weakness of the whole ridiculous system.
When I removed the tire, the rim tape was wrinkled and detaching. This had been professionally installed by a confident technolemming who fully believed in the technology. This was the A game of a committed disciple. It's nice to see that even the true believers can screw the pooch this badly.
Wrinkly
Floppy
And the sealant mess looks like the floor of a triple X adult theater at closing time.
I had estimated a price to throw a tube in there before I saw that the rim tape couldn't be saved. I knew it would be compromised. I didn't anticipate that it would have floated loose completely. It didn't make a huge difference to the price, but it added a bit, as well as requiring more comprehensive cleaning and drying to get new rim tape to adhere properly.
The only way to make a reliably airtight rim is with a fully sealed floor. This requires novel approaches to spoking. The majority of players in the tubeless sector rely on tape. The sealant in its fresh, liquid state actually attacks the adhesive of the rim tape, as seen here. Any flaw in the tape job provides a starting point for the sealant to start weakening it. In addition, rims seem to be coming with shallower center sections now, as well as really tight tire sizing. This means that anyone mounting a tire might take advantage of the absence of an inner tube to use tire levers to pry the casing onto the rim, only to cut the rim tape.
Tubeless makes everything worse, but the fad has not run its course. And like all diseases, it will never be fully eradicated. All we can do is treat it when it flares up and inoculate against it as much as possible.
I had no end of problems with a new wheel. It's a single-wall rim with a deep well. 28mm Muc-off tape didn't work; kept getting punctures at the rim. took it to the bike shop where they replaced it with 19mm velox cotton tape, which worked for about a day, when I saw the tire completely flat the morning after a ride. Saw that the tube a long flat, about 2.5 inches long, where it rubbed against the edge of the Velox tape. Took it back to the shop where they put a layer of gorilla tape on top of the Velox. That worked for a few days, then I heard the tub pop when I was taking it off the car rack one afternoon. I said F this and swapped in an old wheel, then as I test I thoroughly cleaned the new rim with solvent, put in a plain ol' rubber rim strip, and an old tire and tube. It's held fine for a week now.
ReplyDeleteI call those deep double-wall rims "Valley of Death rims, because they cause blow-ins (opposite of blowouts) where the tube expands into the deep channel. I fill the valley with a loop of ordinary clothesline and tape over it as if the rim floor was higher and flatter. 100 percent success rate if done right. Cleaning up after the bike industry once more... We had a whole model year of Fujis with them.
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