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Discussion Starter · #1 ·
I have Vee Mission Command 4-inch tires mounted up with FattyStripper rim strips.

I got a leak today, pretty bad. I had to stop and fill up about every 5-10 minutes. When I got home I took the whole wheel off the bike and dunked it in the bathtub. There was a steady stream of bubbles coming from the seam in the rim. So I figured I had some kind of leak through the FattyStripper, right?

I took the tire off the rim, and the FattyStripper stayed glued to the tire beads all the way around and came off with the tire. Basically making the tire a giant innertube. I was able to inflate the FattyStripper, still on the tire, with the tire totally off the rim. And then I dunked that inflated tire+strip in the tub to see where it was leaking. I checked the entire thing like 10 times and there were zero leaks. I even added more air until I was sure that it was going to pop, but there were NO leaks. The tire sat there for like a half hour with the bulging FattyStripper installed, off the wheel, holding air.

How is this possible? How could it be leaking through the rim, then hold air after I take it off?
 

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will rant for food
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My guess is as follows, using an analogy from my experience with vacuum bagging using mastic tape (similar to window sealant tape) with nylon film. Nylon film is fairly wrinkly in practice. What is a common gremlin for me is when the bag wrinkles just next to the insertion site of a vacuum hose. The wrinkle portion of the film does not directly contact the sealant tape all the way, hence a narrow little path -- a stream of bubbles -- is made available.

The solution to the problem is to stretch the film at the affected site, eliminating the over-and-back of the wrinkle, contacting the sealant, and a good seal is made.

My guess is that your act of taking the tire and strip off the rim in one go allowed the strip to stretch itself fully and eliminate any wrinkles. It is not something you would be able to hear.

Try putting your strip-and-tire assembly back on the rim and see if it now holds.

...Just a guess, bear in mind.
1945840
 

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jalepenio jimenez
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That's impressive that the area where the valve goes through the FS isn't leaking air after being removed from the wheel. I'm stumped by your situation. I've got FS on two bikes with no air leaks. Unfortunately, I seriously doubt you'll be able to re-use the current FS on your tire, but you may be lucky and get the tire back on without compromising the latex FS. If it was me, I would just take the FS off, clean the wheel and inside of the tire, and use a new FS and remount the tire. Don't forget to add sealant before remounting.
 

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Could the stem be leaking under the fatty stripper and out along the rim?

Otherwise, yeah, that's weird since the fatty stripper almost bonds/adheres to the tire in my experience.
 

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Discussion Starter · #5 ·
The valve stem stayed perfectly sealed to the rim strip too.

This is my new theory...

The air bubbling from the rim seam was a red herring. It was just water running into the rim cutouts and pushing out air. In other words it was just spaces in the rim filling with water, but not actually air from the tire coming through the fatty stripper.

There's probably a smaller leak in the tread or sidewall of the tire that just wasn't leaking at the 0.1psi that the tire+stripper were inflated to when I tested it the second time. You might actually need a couple psi to activate the "real" leak in the tire. So if this true I just wasted effort taking the tire off the rim, but the good news is there was never any problem with the beads or strip in the first place.
 

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I've set up a few fat bikes with fatty strippers with their bling strips and have had a tough time with bad leaks coming through the cutouts. The bling strips are the problem imo. They are too stiff and the spoke nipples hold them out from the rim. This leaves an exposed edge that pinches the latex and can cut it when inflated. That said, I have been able to get them to seal satisfactorily by adding plenty of sealant (4 oz per tire) and rotating/riding them.

Fatty strippers work much better with factory nylon liners but then again, so does taping. Good tape jobs also make it much easier to change tires than latex liners that are a one and done deal. Frankly, after using both I will likely stick with taping in the future.
 

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Discussion Starter · #7 ·
I might have spoken too soon... I remounted the tire with a new FS and added 3oz of sealant after seating the beads. After a good shake and bounce now there is Stans oozing out of the rim seam.... there's like no way that could happen unless there is a legit internal leak. Which means the previous go-round is still a bizarre mystery.

What kind of tape do you use? Do you tape all the way up over the bead? I heard about tyvek tape?
 

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jalepenio jimenez
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FWIW I installed FS bling strips in two different fat bike setups. They were spec'ed on the dimensions of the wheel/rim (Sun Ringle Mulefat 80) so fit perfectly. I didn't think they were stiff enough so I put two wraps of clear shipping tape over the bling strips for added stiffness, and have had no trouble with leaks.
 

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Rippin da fAt
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I might have spoken too soon... I remounted the tire with a new FS and added 3oz of sealant after seating the beads. After a good shake and bounce now there is Stans oozing out of the rim seam.... there's like no way that could happen unless there is a legit internal leak. Which means the previous go-round is still a bizarre mystery.

What kind of tape do you use? Do you tape all the way up over the bead? I heard about tyvek tape?
Taping, I will do right up into the sidewalls of the rim to cover vent holes that are present on many rims.
 

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jalepenio jimenez
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I should mention I was redoing a terrible tubeless conversion done by the lbs where I bought the bikes. They did the conversion using Gorilla tape, a major BAD mistake. Sealant was coming through the cutouts on the rim and tires were going flat after an hour out of the shop.
For one, the stock rim strips in the Mulefat rims were so soft that 10 psi in the tire was blowing them out through the cutouts, thus serious leak potential. Combine that with Gorilla tape that becomes worthless in contact with sealant and not only do they leak, but you have a gooey mess to deal with.
The FS bling strips were pretty stout, but adding a layer of shipping tape ensured their viability. Even at 15 psi they don't bulge out through the cutouts.
To clarify: shipping tape is narrower than the width of the rim, consequently I laid it around the rim in contact with the outside of the rim on one side, then another wrap in contact with the outside of the rim on the other side. They overlapped in the middle and were a bit thick where I melted a hole through them and the bling strip for the valve stem, but it worked out great. No leaks.
 
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