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  1. #1
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    Tubeless Burping Problem

    Maybe this has been discussed somewhere but I've not found a decent discussion on this. I'm hoping someone can either point me to one, or help me out.

    I've got no-name 80mm rims and am using 4.4" Jumbo Jims. When I inflate the tire I do hear the tire pop onto the larger diameter shoulder, but it does not lock into place. I think the shoulder it slides up onto is a bit sloped, without a lip to hold it in place. So if I let air out it comes off almost on its own. If I ride with more than about 5psi I'm fine, but at lower pressures I've twice had it go flat, and a few more times have noticed it on time and added more air mid-ride. I'm riding snow and issues have usually been with frozen ridges or sidehills or other more hard features. I'm 160lbs, so I'm not overloading it, and should be able to go lower to get the most out of the bike in soft conditions.

    The "easy" solution is to go out and drop a bunch of $$ on new rims, but I'm not going to do that. I want to glue the tires to the rim. I've heard of using the glue used for tubular tires, but have not heard much about that. Is that the best option? Are there other glue options to consider?

    Or, does a half tube method solve this? I'm not sure that it would but seem to have seen some suggestion of this. Maybe a half-tube with glue would make this a "whole tube"?

    Thanks,
    Peter

  2. #2
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    Quote Originally Posted by peterw3980 View Post
    I think the shoulder it slides up onto is a bit sloped, without a lip to hold it in place.
    Do you have a diagram/profile image of the rim? Often the issue is the bead slipping back into the centre channel rather than being held up against the wall. You can often build up a better profile to help hold it there using tape.

    Or, does a half tube method solve this? I'm not sure that it would but seem to have seen some suggestion of this. Maybe a half-tube with glue would make this a "whole tube"?
    Yes a half-tube or rim-strip method can help with tubeless. The sealant essentially glues the tyre to the tube/strip, however keep in mind how difficult it then is to remove the tyre, especially on the trail if required. Although not on a fat bike, I run rim strips on one of my wheelsets (narrow, non-ideal rim) and even letting all of the air out I struggle to break the seal by hand.

  3. #3
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    Sorry, I don't have a photo of the cross section, and don't have the time to unmount my tubeless setup at the moment. I'm a mechanical engineer though, and have a pretty good feel for the physics of this staying mounted. I've seen some pics of other rims and can see why some would stay mounted better than mine. If I do have a bead failure and have it apart though I will have a closer look and some pics.

    When I did the tubeless setup previously with other tires I put a strip of weather stripping on the sloped edge of the shoulder to create a bit of a channel at the edge, but found that I had to trim it down very low or the tire would not even snap up onto the shoulder at the edge. BTW - does the term "shoulder" make sense? I'm not sure if this is the common term or if there is a better one.

    Thx, Peter

  4. #4
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    Split tubeless may be the answer to your problem. I've had great success setting up Surly rims, which are not designed to be run tubeless.
    I recently built a set of My Other Brother Darryls for my bike and tubeless was EASY. I ran my tires at a lower pressure in the last snow storm than ever before.
    You MAY have success with a couple wraps of gorilla tape over the rim and split tubeless on top of it. I did some Bikes Direct wheels like this for friends. Two out of three of them ended up having me build them new wheels.
    Sorry to keep saying that but it really is the more permanent answer.
    Last edited by NYrr496; 02-09-2017 at 10:17 AM.
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  5. #5
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    Thanks, I'll try a few solutions before I change rims. I've been through a few different tweaks to the shoulder shape this winter with the weather strip and tape, so am really leaning more to the glue option. So, I was hoping for some input on any other glues to consider, and if there are options, what the pros and cons are.

    As an aside, I should add that ideally I would build some carbon rims. And I mean BUILD them. I've built 480 gram carbon SUP paddles and recently built a carbon kite hydrofoil. The material cost is very low. I might build a carbon fatbike since I've built lots of hollow tubes before. For rims I just need some kind of mold to build one on, because as I am finding out, the shape seems to be critical!

    Peter

  6. #6
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    I dont think think that shoulder (sidewall) of the rim holds the air, especially on low pressures when tire start to move there.
    I suppose its bead base that holds air.
    And air start to escape when there is too much gap for sealant to work, and too low pressure for rim sidewalls to help.
    Split tube method effectively increases rim diameter and should help. The same is with foam methods and tape.
    Another method is to use thicker sealant - Stans now sells new "racing" sealant which should help building tire bead diameter quicker, I was able to seal some tires which were loosing air with regualar Stans. It cannot be injected via valve though.
    Also I always take a hand pump on rides into backback as even on tubeless ready rims and tubeless ready tires pressure can drop too much due to sidewall flex. Just pump it up, ride and allow sealant to work. After some time sealant will grow making tire difficult to remove without motorcycle levers.

    Sent from my SM-G900F

  7. #7
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    Yeah it's not the lip at the top that helps you, but what I would describe as the "bed". If the bed is big enough, or has a bead lock on it, then it keeps the tyre bead secure. I've accepted that I suck at explaining this stuff, so try this: Trail Tech: Off the hook - BikeRadar

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    That's a good link. I was not talking about the bead hooks. I thought they looked pretty good, but apparently they're old tech based on that article. What I referred to as the shoulder is the slightly larger diameter circle that the tire has to slip up onto when it pushes out to the edge when mounted. In that article though you can see that they talk about a "drop channel" where once the tire is pushed out to the edge it is hard to slip back into the middle without pushing the tire up over a small lip. That small lip is what I'm missing on my rims.

    There was mention of some bikes direct rims. My bike is a KHS which I think might have the same frame as a Boris, so they might be similar rims too.

    I'll have to look into the other sealant option too.

    I'm still hoping to hear from someone about glue. I was under the impression that this is one of the solutions, but no one has said anything about it yet. Maybe the only people who have used glue are the few who briefly mention it online? Will tubular glue make a mess of the tires so I regret it if I do go with some other option at a later date? I don't think I need really strong glue, just a bit to help hold it

    Thanks,
    Peter

  9. #9
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    Tubular tire glue was used on old-school snowbike stuff (specifically, SnowCat rims) 10+ years ago to bond one bead of the (very loose fitting) tire to the (undersized) rim. This was when using tubes. The point was to keep the tire from spinning on the rim at low pressures, which would eventually shear the valve stem out of the tube.

    I've not heard of anyone using glue on the beads in a tubeless application.

  10. #10
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    Glueing on a split tube to make a fatbike tubular

    OP - I've tried exactly what you're talking about, on Weinmann rims (probably what's on your KHS), as they have no bead shelf and are a nightmare to keep from burping. Using the split tube method with sill foam under, I put contact cement glue on the split tube where the bead would make contact with the tire inflated It kind of worked, but was a world class PITA, and then there's no way to get old sealant and stanimals out without tearing it apart. You might have better luck with the right glue (tubular glue), but I didn't have any on hand. I hate those weinmann rims.
    I would advise not taking my advice.

  11. #11
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    yeah, tubeless ready rims FTW.

    that's really the problem here. crappy rims. nothing you do is going to really solve this problem. you might be able to make it better, but I'd rather drop some coin to make sure it works than to invest a bunch of time and hassle into "maybe"

  12. #12
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    There's a huge post on setting up weinman 80 rims tubeless, and the general consensus is split tube is the only thing that works, and it still kinda sucks.
    How are the Weinmann HL80's for tubeless?

    Have to build the center channel up with foam (sill foam is commonly used) to help seat the rim, and then wait for the sealant to dry really well between the 24" split tube and the tire so it doesn't come unsealed. Also can't go too low of pressure because even with split tube, you can still easily push the tire off the bead shelf (shoulder) because in time, that foam is compressed and shrinks. Nothing to hold the tire's bead on the bead shelf, and it'll just slide right off.

    Glue it all up, and it will hold. complete pain to take back apart though.
    "a hundred travel books isn't worth one real trip"

  13. #13
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    I think glue is going to be a HUGE PITA. And what happens if you get a flat on the trail?

    Obviously, the best solution is new tubeless ready rims.

    But I think you can get it to work better with a little tape work. I'd suggest taking the tires off and then removing whatever tape is on there now. Then you need to build up a bead lock bump. Basically a raised section that the tire bead has to slip over when the bead seats, and keeps it from sliding back to center. Really thin strips of Gorilla tape works well for this, as it's pretty thick. Then you run the normal tubeless/Stan's tape over that all the way to the outside of the rim. If done carefully and correctly, this should solve your issue.

    People also use this method on Velocity Dually rims, which also lack that shelf the keep the bead set.

    Good luck!

  14. #14
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    If the OP's rims are weinman 80's, building them up with tape is really difficult. These are single wall rims, and the bead shelf is only 1/4" wide. Not enough room to build up a lip on the shelf. The rim profile is a lot like the sun-ringle "villa" rims about halfway down this link. The only way to do it is add something behind the bead shelf to create additional width. I'm probably going to spend some time this weekend doing something similar because my boris is begging for some more ride time, and I'm tired of it falling off the rims when a tube runs low on air.
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  15. #15
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    Split tubeless, as mentioned above. Extra rubber from the tube will fill in the gaps, and make the bead fit tight. Use lots of soapy water to make sure the bead seats, and you should be good.

  16. #16
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    Hmmm...I had expected to hear from someone who's used glue, and was hoping there was some kind of glue which is strong enough to maintain the bead and yet could be pulled apart on trail with levers if needed. Seems that might not be the case.

    Yes, my rim shelf (formerly known as "shoulder") is very narrow. I'd be surprised if its a 1/4", probably 3/16" wide at best. I think I will build up a more solid lip on the 45 degree slope next to the shelf and see if I can solve it that way. I think if I build up a bigger lip around maybe 90% of the rim I can prevent 90% of the problems and not have too much trouble slipping it over the ridge I'll build. My rim does not have that pronounced box at each corner as seen in the Villa diagram.

    It sounds like my issues are not as bad as some people report on the other thread. I was out on 6psi no problem last night but given the extremely challenging conditions we have right now - loose ice pellets which pack as well as ball bearings - I would have liked to try close to 2 psi. Since my setup works in most normal conditions I might wait till the winter's over before I try something drastic!

    Thx, Peter

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