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  1. #1
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    Burping Ground Control on Flow - advice?

    I've been burping my rear tire frequently, and would love some pointers to how best to deal with this.

    Wheel setup: Ground Control 2.3 on Flow rim, Stans Sealant. (on teh front, have a Purgatory 2.4). Usually run 25/22 PSI by my pump, but I think it may be soft. Mojo HD.
    Condition: Tires are a little tired, and I'm hoping in part for information to help my decision about replacing them. The rear rim has a few small dents - could that be part of the issue?

    I find I burp really frequently, the main situation it happens in is when I catch a little air, and land sideways off a hip or kick the wheel out and drive the wheel sideways on landing. So, I guess side loading the tire is the issue?

    Anyhow, I'd guess that my short term solution is to:
    -straighten the rear rim damage (how?)
    -get a new rear tire (what kind might be better for this? Generally I like faster rolling, medium volume rear tire to go with a bigger more agressive front)
    -Go UST? (want to avoid the weight penalty!)
    -Higher pressure? (really like the softer for traction and feel...)

    Are any of these wrong? What else am I missing? What's the key solution that I can do to compromise least on weight or ride feel?
    Thanks for any input!

  2. #2
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    How easily did the beads snap to the rim when inflating? If the bead snaps on at a low pressure, it'll come off momentarily (=burp) also.

    I set up my wheels with enough tape to require at least 30 psi to snap them on with lubricant (soapy water). Never had a single burp. Crest + Stan's tape + 2.35 Nobby Nic TLR SS Evo.

  3. #3
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    Good question. They go on pretty easily. Maybe I'll go back to my schwalbe love/hate relationship (love the performance, hate the price and fast wearing) and see if that sticks better.

  4. #4
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    Which GC are you using? There are three variants, tubed, tubeless ready and UST. I'm using the UST on Sun Ringle Infernos, no issues other than they're heavy and not very compliant. I'm not going to use UST tires again. The tubeless ready tires are much more supple and stay on the rim.

  5. #5
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    If you have a few small dents, I'm guessing you're running things pretty soft back there. And, your pump might not be accurate. The results are always repeatable, sure, but "25PSI" might actually only be 20psi.

    I'd go to 30 and see if the problem persists.

  6. #6
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    I have exactly the same combination on the back of my Banshee Paradox. Ground Control (2Bliss) but 2.1 on a Flow and I've never had a problem. (The dents in your rim aside. I have no idea if that is contributing to your problem or not.) My wheels were built by Mike Curiak (lacemine29.com) and they arrived with a double layer of yellow tape. I asked him why and he told me that it helps looser tires fit tighter.
    The trouble with having an open mind is that people will insist on trying to put things in it.

  7. #7
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    Quote Originally Posted by mikemikemike View Post
    I've been burping my rear tire frequently, and would love some pointers to how best to deal with this.

    Wheel setup: Ground Control 2.3 on Flow rim, Stans Sealant. (on teh front, have a Purgatory 2.4). Usually run 25/22 PSI by my pump, but I think it may be soft. Mojo HD.
    Condition: Tires are a little tired, and I'm hoping in part for information to help my decision about replacing them. The rear rim has a few small dents - could that be part of the issue?

    I find I burp really frequently, the main situation it happens in is when I catch a little air, and land sideways off a hip or kick the wheel out and drive the wheel sideways on landing. So, I guess side loading the tire is the issue?

    Anyhow, I'd guess that my short term solution is to:
    -straighten the rear rim damage (how?)
    -get a new rear tire (what kind might be better for this? Generally I like faster rolling, medium volume rear tire to go with a bigger more agressive front)
    -Go UST? (want to avoid the weight penalty!)
    -Higher pressure? (really like the softer for traction and feel...)

    Are any of these wrong? What else am I missing? What's the key solution that I can do to compromise least on weight or ride feel?
    Thanks for any input!
    Not enough pressure is likely the culprit. With Spesh TLR or UST, I usually still run 36-38 psi with enough traction on the climbs and descents with no loss of air, burp or feel or rim with big jumping, hard cornering whatsoever. Even though that sounds like a lot of pressure, if I ran <35psi in rear tubeless or not, things get a little too flexy, squirmy on the descent for me, but I do weigh 220lbs geared and abuse my gear. I personally think people go weigh too low with tire pressures. My take is run as much as you can without loosing traction on climb or descent or causing a harsh or wheel bucking ride. If front/rear suspension is dialed and working well, there is no need to go low pressure. If dual ply tires and on a hardtail, with thick/big volume tires, I may go lower, but not much. Your rims will thank you later and last much longer with higher pressures, but not too high as Stans Flow EX say max 38psi recommended to stay in place. I am usually 36-38psi rear with thick UST tires, 33-35psi front dependent on how my fork is feeling/sagged.
    Ride On!

  8. #8
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    Quote Originally Posted by jgusta View Post
    Not enough pressure is likely the culprit. With Spesh TLR or UST, I usually still run 36-38 psi with enough traction on the climbs and descents with no loss of air, burp or feel or rim with big jumping, hard cornering whatsoever. Even though that sounds like a lot of pressure, if I ran <35psi in rear tubeless or not, things get a little too flexy, squirmy on the descent for me, but I do weigh 220lbs geared and abuse my gear.
    I don't agree with you and I think the general consensus is with me. On one bike I have Purgatory Controls, 2.4 and 2.2 and run 24/28psi. front/back. I'm 215lbs. without gear. If I ran the pressure that high I'd bounce of every root and rock.
    The trouble with having an open mind is that people will insist on trying to put things in it.

  9. #9
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    Quote Originally Posted by Ronnie View Post
    I don't agree with you and I think the general consensus is with me. On one bike I have Purgatory Controls, 2.4 and 2.2 and run 24/28psi. front/back. I'm 215lbs. without gear. If I ran the pressure that high I'd bounce of every root and rock.
    I know I am not in the general consensus with this at all, as the trend is towards lower and lower tire pressures for better trail grip/compliancy. And yes, lower pressure does acheive this, but at risk of a sloppy ride for me on the descents due to too much tire flex laterally and risk of damaging my rims, losing air, etc. If you can get away with the pressures you are running at your weight without the above, I would by all means go for it. Also, lots of variances between pressure gauges, so can be really hard to tell exact pressure as my guage compared your would likely read differently. I have found if I run enough pressure to not lose traction with steep climbs (live in wet PacNW with lots of wet rocks, roots) or my tire bouncing /skidding around too much on the descent, then I run as high as I can for stiffer set-up of rear wheel and faster roll to carried my speed through techy sections. Tire/wheel slop is my pet peave when riding and I have to run a little more to avoid and doing a lot of jumping with lower pressures sucks too to minimize bottom out of suspension and rim damage too. There is obviously no exact setting for tires to be perfectly ran in every condition, but a balance between low and high seems to work for me. Low enough to hug the terrain, but high enough to roll fast and charge through sections.
    Ride On!

  10. #10
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    I'm with Jgusta on this. It sounds like it's clearly a case of needing more air pressure. Burping is pretty much the definition of not enough air with tubeless. If you're really riding rocky, rooty terrain, you will need more pressure than some say, especially with regular sidewalls.

  11. #11
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    Burping Ground Control on Flow - advice?

    First, check accuracy of your pressure gage. If it is 10 percent off you're actually running 25/22. In any event I think You are running too low. Start at 30/30 psig and re-pressurize every ride and slowly work your way down, every third ride or so, till you stop burping. I'm 180 pounds and I would not go 24. I ride about 29/27. Then again I'm old school and was holding out on tubes at 45 psig until two years ago.

  12. #12
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    Good question. Definitely not the UST. I agree that I'd prefer to stay with tubeless ready, unless UST is really the only way.

  13. #13
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    Quote Originally Posted by mikemikemike View Post
    Good question. Definitely not the UST. I agree that I'd prefer to stay with tubeless ready, unless UST is really the only way.
    Yep, UST is only needed for the thicker sidewall protection. If you are not ripping the TLR Control casings I would just stick with that, but with a little more pressure in there
    Ride On!

  14. #14
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    Thanks for all the great replies.
    Consensus seems to be up the pressure and experiment.
    I ordered a rim rench to straighten out the dings. Perhaps I should invest in a digital gage or higher quality pump to check actual pressure.
    Either way, I will start higher pressure. I just like the ride feel of lower pressure so much, would love to find a way to keep it.
    I'll also try to replace with a Hans Dampf I have lying around and see how that goes - rarely burped those when I ran them.

  15. #15
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    Casings are fine - I can see the threads in many places, but no tears. I have torn the lightweight casings on Schwalbes, and blown out a pair of FastTracks or whatever the more XC specialized version is, but what I have now seems to be holding up OK, and Snakeskin gives me lots of confidence. Only ride sharp rocky terrain when I travel, pretty much.

  16. #16
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    I was running a 2.1" Specialized Ground Control tire on my Flow rim for a little while, and it needed about 35 psi to keep it from squirming and bottoming on the rim. I ran a Specialized Chunder 2.2" for a couple of years, and that needed about 30 to feel right. I weigh about 190 and ride a lot of rocks and roots. I ripped through the sidewall of a 2.2" Purgatory in about 5 hours with 32 psi, so I find that I need a bit more psi with Specialized tires than other tires I've ridden. I only need about 28 psi in my WTB Wolverine 2.2" UST tire. All of these tires were ridden on the back wheel.

  17. #17
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    Increasing the pressure is a compromise.

    Try to set up your wheels and tires so you can run your preferred pressure without burping.

    Your tires snapped on easily -> add a round or two of rim tape or switch to a rim strip.

  18. #18
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    Yes, that's the compromise I'm trying to avoid.
    But a Hans Dampf on. Snapped on at about 40psi. Ran a little higher pressure with no issues. I will lower pressure slowly and see what happens.

    Quote Originally Posted by Saul Lumikko View Post
    Increasing the pressure is a compromise.

    Try to set up your wheels and tires so you can run your preferred pressure without burping.

    Your tires snapped on easily -> add a round or two of rim tape or switch to a rim strip.

  19. #19
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    I'll 3rd Jgusta's too low pressure comment.

    The OP: mikemikemike wrote;
    "I find I burp really frequently, the main situation it happens in is when I catch a little air, and land sideways off a hip or kick the wheel out and drive the wheel sideways on landing. "

    This is not a 22 psi on a trail tire situation.

    Low pressure is great when you are absorbing the ground while you are on the ground and in a straight line.

    Landing jumps sideways will max out all of your equipment as it is one of the most extreme force events on a bike.

    If you want to jump, you'll have to up the pressure for landing control.

    Or get a more solid sidewall tire.

    NotTubes equation for tire pressure has been pretty spot on for me (rider weight = rider + pack & water):
    Tire Pressure

    P

  20. #20
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    Re: Burping Ground Control on Flow - advice?

    Aren't Stan's BST and UST/TLR standards not considered totally compatible? I've never burped at a variety of pressures with Specialized 2Bliss tires on UST and TLR rims. I've never run Stans rims, but have read that UST/TLR tire beads don't necessarily play nice with Stans BST rims. They are designed for running standard tires tubeless, after all.

    Sent from my XT907 using Tapatalk 2

  21. #21
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    Quote Originally Posted by ewarnerusa View Post
    Aren't Stan's BST and UST/TLR standards not considered totally compatible? I've never burped at a variety of pressures with Specialized 2Bliss tires on UST and TLR rims. I've never run Stans rims, but have read that UST/TLR tire beads don't necessarily play nice with Stans BST rims. They are designed for running standard tires tubeless, after all.

    Sent from my XT907 using Tapatalk 2
    Most are compatible with Stan's rims:
    Recommended Tires

    P

  22. #22
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    Sounds reasonable. But I want it all - waaahhhh!

    I'm probably 165 w/gear, so I'm pretty close on pressure by stans formulas.

    -mk

    Quote Originally Posted by Mr.P View Post
    I'll 3rd Jgusta's too low pressure comment.

    The OP: mikemikemike wrote;
    "I find I burp really frequently, the main situation it happens in is when I catch a little air, and land sideways off a hip or kick the wheel out and drive the wheel sideways on landing. "

    This is not a 22 psi on a trail tire situation.

    Low pressure is great when you are absorbing the ground while you are on the ground and in a straight line.

    Landing jumps sideways will max out all of your equipment as it is one of the most extreme force events on a bike.

    If you want to jump, you'll have to up the pressure for landing control.

    Or get a more solid sidewall tire.

    NotTubes equation for tire pressure has been pretty spot on for me (rider weight = rider + pack & water):
    Tire Pressure

    P

  23. #23
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    I burped my GC 2.3 FRONT tire... Then went OTB, then wondered WTF just happend. 28psi and it let go to about 8psi.

    Learning hurts

  24. #24
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    I did the same with a nobby nic at jackson hole bike park on my old trail bike off a mid-sized table a few years back. concussion and two broken ribs.
    remind me why I'm still riding tubeless again?

    Quote Originally Posted by -Todd- View Post
    I burped my GC 2.3 FRONT tire... Then went OTB, then wondered WTF just happend. 28psi and it let go to about 8psi.

    Learning hurts

  25. #25
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    I wasn't hurt (thankfully), I think my issue was related to the slow speed descent and the rut that my tire was tugging into... Sh!t happend, and it burped, which dropped the tire enough to put me OTB... Lesson learned, I need a shorter stem...


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