Catastrophic Air Loss on Tubeless Air
04-22-22, 04:53 PM
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04-22-22, 04:55 PM
#52
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I'm going with the "rolled the tire" hypothesis. You might have had a puncture or leak that sealed itself up, but not before losing enough pressure to leave the tire susceptible to "burping" in turn.
Also I would check the taping job on this. If the bead is not tight against the bead shelf, then it is more susceptible to losing air if the bead is briefly unseated.
Also I would check the taping job on this. If the bead is not tight against the bead shelf, then it is more susceptible to losing air if the bead is briefly unseated.
04-22-22, 07:15 PM
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I was not assuming anything, but what could be related would be if the tape did not go all the way to the edge of the rim ( up to the wall). Sometime people think that they only need to cover the spoke holes with the tape, but in most cases the tape should go from wall to wall. The thickness of the tape makes the bead seal tighter against the bead shelf (the flat part on the rim that the bead sits on before you seat the tire).
04-23-22, 05:13 PM
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I was not assuming anything, but what could be related would be if the tape did not go all the way to the edge of the rim ( up to the wall). Sometime people think that they only need to cover the spoke holes with the tape, but in most cases the tape should go from wall to wall. The thickness of the tape makes the bead seal tighter against the bead shelf (the flat part on the rim that the bead sits on before you seat the tire).
The tape I am using is the tape that was sold by the wheel manufacturer for use on these specific wheels. Let’s set aside for the moment whether it reaches from “wall-to-wall”. It doesn’t, although it is close. Instead, let’s focus on your claim that the thickness of the tape is important to how tightly the tire bead fits on the shelf and in turn the retention of the bead there.
Measured using a digital micrometer accurate to 0.5 microns (not a caliper), the tape is about 3 mils thick, including adhesive. That’s 75 microns or 0.075mm, which is pretty typical of these tapes from the ones I have seen. On a 700c wheel, with 622 mm diameter, the tape will therefore increase the diameter (and the circumference) by .150/622 = .024% = 240 ppm. Now, before you say, “but… that’s IMPORTANT”, let’s consider whether it can be. In particular, the CTE (coefficient of thermal expansion) of the Al rim is 23 ppm/C, and for the Kevlar bead it’s actually negative, about -3 ppm/C. So, the total CTE mismatch between the Al rim and the tire is about 26 ppm/C. That means, if I mount a tire on an Al wheel, and cool it down by (240 ppm)/(26 ppm/c) = 9 C, the tire will become as much looser on the rim as if I omitted the tape from the shelf. So, in claiming that the tape is somehow important to safe fit of the bead on the shelf, you are also saying that a wheel setup that is safe at temperature T is NOT safe at temperature T-9C. This is obvious nonsense, and I’m not sure why you would say this after your acknowledgement in another post of the fact that tire pressure is what keeps the bead on the shelf, a force which is huge compared to friction between the bead and the rim. (It also ignores the facts that tire manufacturing tolerances are going to be important at this level, and that the tire bead loosens up and stretches with use by a significant amount, as anyone who has ever rotated tires on a tubeless setup knows.)
So… look… while I specifically stated that I wasn’t interested in the peanut gallery’s opinions here, I don’t mind the honest, informed, constructive addition of thoughts to the thread. However, if all you have is a bunch of pseudo-expertise and old wives’ tales, just save yourself the effort of posting, and save me the effort of debunking your nonsense.
04-23-22, 05:49 PM
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Well, Mr. Expert, now you've gone and said something that is verifiably complete and utter nonsense.
The tape I am using is the tape that was sold by the wheel manufacturer for use on these specific wheels. Let’s set aside for the moment whether it reaches from “wall-to-wall”. It doesn’t, although it is close. Instead, let’s focus on your claim that the thickness of the tape is important to how tightly the tire bead fits on the shelf and in turn the retention of the bead there.
Measured using a digital micrometer accurate to 0.5 microns (not a caliper), the tape is about 3 mils thick, including adhesive. That’s 75 microns or 0.075mm, which is pretty typical of these tapes from the ones I have seen. On a 700c wheel, with 622 mm diameter, the tape will therefore increase the diameter (and the circumference) by .150/622 = .024% = 240 ppm. Now, before you say, “but… that’s IMPORTANT”, let’s consider whether it can be. In particular, the CTE (coefficient of thermal expansion) of the Al rim is 23 ppm/C, and for the Kevlar bead it’s actually negative, about -3 ppm/C. So, the total CTE mismatch between the Al rim and the tire is about 26 ppm/C. That means, if I mount a tire on an Al wheel, and cool it down by (240 ppm)/(26 ppm/c) = 9 C, the tire will become as much looser on the rim as if I omitted the tape from the shelf. So, in claiming that the tape is somehow important to safe fit of the bead on the shelf, you are also saying that a wheel setup that is safe at temperature T is NOT safe at temperature T-9C. This is obvious nonsense, and I’m not sure why you would say this after your acknowledgement in another post of the fact that tire pressure is what keeps the bead on the shelf, a force which is huge compared to friction between the bead and the rim. (It also ignores the facts that tire manufacturing tolerances are going to be important at this level, and that the tire bead loosens up and stretches with use by a significant amount, as anyone who has ever rotated tires on a tubeless setup knows.)
So… look… while I specifically stated that I wasn’t interested in the peanut gallery’s opinions here, I don’t mind the honest, informed, constructive addition of thoughts to the thread. However, if all you have is a bunch of pseudo-expertise and old wives’ tales, just save yourself the effort of posting, and save me the effort of debunking your nonsense.
The tape I am using is the tape that was sold by the wheel manufacturer for use on these specific wheels. Let’s set aside for the moment whether it reaches from “wall-to-wall”. It doesn’t, although it is close. Instead, let’s focus on your claim that the thickness of the tape is important to how tightly the tire bead fits on the shelf and in turn the retention of the bead there.
Measured using a digital micrometer accurate to 0.5 microns (not a caliper), the tape is about 3 mils thick, including adhesive. That’s 75 microns or 0.075mm, which is pretty typical of these tapes from the ones I have seen. On a 700c wheel, with 622 mm diameter, the tape will therefore increase the diameter (and the circumference) by .150/622 = .024% = 240 ppm. Now, before you say, “but… that’s IMPORTANT”, let’s consider whether it can be. In particular, the CTE (coefficient of thermal expansion) of the Al rim is 23 ppm/C, and for the Kevlar bead it’s actually negative, about -3 ppm/C. So, the total CTE mismatch between the Al rim and the tire is about 26 ppm/C. That means, if I mount a tire on an Al wheel, and cool it down by (240 ppm)/(26 ppm/c) = 9 C, the tire will become as much looser on the rim as if I omitted the tape from the shelf. So, in claiming that the tape is somehow important to safe fit of the bead on the shelf, you are also saying that a wheel setup that is safe at temperature T is NOT safe at temperature T-9C. This is obvious nonsense, and I’m not sure why you would say this after your acknowledgement in another post of the fact that tire pressure is what keeps the bead on the shelf, a force which is huge compared to friction between the bead and the rim. (It also ignores the facts that tire manufacturing tolerances are going to be important at this level, and that the tire bead loosens up and stretches with use by a significant amount, as anyone who has ever rotated tires on a tubeless setup knows.)
So… look… while I specifically stated that I wasn’t interested in the peanut gallery’s opinions here, I don’t mind the honest, informed, constructive addition of thoughts to the thread. However, if all you have is a bunch of pseudo-expertise and old wives’ tales, just save yourself the effort of posting, and save me the effort of debunking your nonsense.
Good luck.
