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I've read all questions found by my keywords, but didn't find and answer.

I have a gravel with Triban tubeless ready rims and Hutchinson Overide tubeles ready tires. They already had a rim tape setup. One wheel has no problem but the other one was losing air harsh throug exactly one spoke hole. I sanded the rim with sandpaper. Changed a rim tape four times. Tried one layer and two layers. Tried 21mm and 25mm tape. Tried valve seals of different shapes. Nothing helps, each time air is loosing through the same spoke hole.

So, I have two questions

  1. Are spoke holes on tubeless ready rims should be airtight? I thought that they should not and that's why rim tape is needed. But in this case I can't understand why air loosing through one spoke hole only but not through all of them.
  2. What would you recommend to FIND and solve the root of the problem? :)

I use two rim tapes, one Muc-off and one noname and Muc-off sealant.

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Spoke holes on most tubeless rims/wheels are in no way trying to be airtight. It's the opposite on many of them; for many carbon rims you want air to be able to flow out of the lower rim cavity because the wall section is ultra thin and rims sometimes can fail around the bond area with the upper cavity if the lower one is pressurized. That's the reason for products like the Enve pressure release valve stem nuts.

It sounds like you're getting air coming out of a spoke hole. All that's telling you is there's a leak somewhere on the tape/rim side of what should be the pressurized area. Once that's true it's always going to find somewhere to come out.

Several things could be going on here:

  • There's a problem with the tape that's been recreated despite the number of times you've gone through it. Sounds unlikely to me but it is possible. You're looking for flat, no bubbles, coverage such that the tire is touching the tape and leaves no rim exposed, and a good flat neat ending area.
  • The sealant you're using isn't working for whatever reason.
  • You're getting leakage at the valve area. Possible causes could be a bad match in shape, the valve hole not being formed neatly enough, or the nut not being tight enough. This is probably the most likely in a sense, but it bears pointing out that sealants vary in how good they are at nullifying issues at the valve. Most of them are pretty good, but it would make sense to me that Muc-off would struggle more because it's not a good gap filler.
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  • is there a specific brand or type of sealant that is "opposite" to muc-off in its abilities and characteristics?
    – Criggie
    Mar 13, 2022 at 21:31
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    @Criggie Stans Race would be the quintessential aggressive sealant.
    – MaplePanda
    Mar 13, 2022 at 22:55
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    @Criggie I wouldn't say opposite and I don't claim to understand the chemistry or physics, but my understanding is Muc-off is one of the type of sealants that try to jam holes with a particulate rather than clog it with latex. All the sealants I know of like this (Muc-Off, Finish Line) seem to have problems with doing what they're supposed to do sometimes. Mar 14, 2022 at 7:15
  • Unfortunatelly all these suggestions about sealant and valve issues do not explain why one wheel work well but another experiencing problems :( Also the question why air is coming through the same and the single spoke hole is still open. Is there a reliable way to find where rim tape could loose the air?
    – Ed Pavlov
    Mar 15, 2022 at 9:20
  • @EdPavlov The potential explanation is that it could be leaking due to the physical particulars of how airtight the valve is sealing up at the valve hole in the rim/tape on that rim, which depends on how neatly the tape was pierced and things like that, i.e. a clean hole vs the tape being a little clumped up. That it's coming out of a particular spoke hole doesn't matter because the lower rim cavity should never be pressurized to begin with; that's what the tape is trying to prevent. Mar 15, 2022 at 16:42

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