Curious if anyone here might know what failed here- Mtbr.com
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  1. #1
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    Curious if anyone here might know what failed here

    Tire - Trek SE4 29er, just over 200 miles on it.
    Rim - Nox Farlow 29er, same
    Tubeless setup, 6 months old
    Would lose like 1-2 psi over a couple of days if left standing in storage

    Was riding at Snowbird on Sunday, little cold and wet. Tire was at 28+psi at start of day at base parking lot. Did 1 run no problems. Very early on second run, cruising at a good clip (20-21mph), almost perfectly straight, very little rocks. Went over a small roller/water berm, maybe 4 inches tall. Not sure if it was on take off or landing of the small airborne, but had a failure.

    VERY LOUD BANG from front tire. Peripheral vision shows me the tire is no longer on the rim, I see yellow rim strip instead. BIG crash.

    After gathering my senses, walk back up trail. I do see one rock, slightly bigger than a fist, but thats about it. Later in the week, inspect tire off the rim, nothing obvious for tears or punctures. Check rim, hardly a scratch anywhere. Haven't yet taken to bike shop, recovering from injuries first.

    So what the hell might have caused this?

  2. #2
    mtbr member
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    tell us about your tubeless installation procedure that was performed with this wheel and tire.

  3. #3
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    Done by the shop, who built up the bike for me.

  4. #4
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    inspect the bead very closely. posting clear, close up pics would be even better.

    the most probable answer is that the bead failed. it would have stretched when doing so. it could have previously stretched if a compressor was improperly used during the installation.

    most carbon rims are now hookless, including the nox farlow. the bead could become unseated at low pressure like any other clincher but at 28 psi that shouldn't happen. if you're just estimating about the pressure it may have been lower than you realize.

    rim damage seems like it would be much easier for you to notice, but that's possible also.

    maybe there are other plausible explanations as well.

  5. #5
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    You didn't state what you weigh, so while 28 PSI might seem high to most, if you weigh north of 250lbs and are riding very aggressive, it really is not. Add to that a few sideways landing putting side load on the tyre/rim interface and maybe a small burp or two you may not have realised and you could have had way too low pressure in there when you landed this particular little jump, maybe with wheel slightly crooked and bang, huge burp and tyre off rim.
    Last edited by LyNx; 08-12-2016 at 05:57 AM.
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  6. #6
    mtbpete
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    You are using a tubeless ready tire, correct?

    If so, my guess is that either the tire has a flaw or the pressure was too low. The pressure that your pump reads may not be accurate and/or the pressure is too low for your weight.

  7. #7
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    the right way to use a compressor to seat a tubeless tire is to regulate the input pressure such that it can't exceed some number that you're sure won't cause the tire to blow off the rim. say 45-50 psi for a standard tubeless MTB tire. whatever is on the sidewall, at the very most.

    just saying that for the OP's benefit. the best possible scenario is what Lynx described, since no one but the rider has done anything wrong, and he can correct it in the future. if the tire was defective, it's now kind of hard to prove that now compared to it being overinflated. most tire manufacturers would warranty such a tire.

    but the first thing is to find the issue, which is probably on the tire's bead.

  8. #8
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    28+ psi via pump I use before every ride, including this one. Though I did not recheck prior to second run.
    I am a clydesdale at 240lbs.
    I generally don't ride that aggressively, meaning charging hard into rocks or going for big jumps. Definitely wasn't this time as it was slick out and the SE4 is ok for wet conditions.
    Yes, Trek SE4 is the tubeless ready, heavy duty (aka enduro) version of the XR4.
    Bike is a 2016 Remedy 29er carbon, with a F36 150mm front,


    So basically sounds like pressure might have gotten low after first run and just had a freak instance there.

  9. #9
    Wanna ride bikes?
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    I would be interested to see what would happen if you re-mount that tire. however, i would NOT ride it on a trail, parking lot only. if it were me i would replace that tire no matter what.
    Rigid SS 29er
    SS 29+
    Fat Lefty
    SS cyclocross
    Full Sus 29er (Yuck)

    Stop asking how much it weighs and just go ride it.

  10. #10
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    Yep, tire is getting replaced. Wanted something a bit more aggressive anyway. Like a DHF or Aggressor or similar. Just not so sure now about staying with Trek, the SE5 look(ed) good.

  11. #11
    mtbr member
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    Quote Originally Posted by nord1899 View Post
    Yep, tire is getting replaced. Wanted something a bit more aggressive anyway. Like a DHF or Aggressor or similar. Just not so sure now about staying with Trek, the SE5 look(ed) good.
    you've got a money back guarantee on the SE4, so I'd use it and upgrade to the SE5.

  12. #12
    transmitter~receiver
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    sounds like your tire blew off the rim.

    i'm with ColinL on this one.
    Quote Originally Posted by pvd
    Time to stop believing the hype and start doing some science.
    29er Tire Weight Database

  13. #13
    change is good
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    Weird. I'm a little lighter, but run same pressures with Farlows. My SE5 has not blown off. The 2.5 DHF is also a nice tire. The Aggressor is good, if you have more of a priority on speed. Personally, I would go DHF. I got a rim stike two times at 26lb with my SE5. Now I'm wondering if the bead is damaged. The DHF has a bigger volume and a stiffer casing. No problems at 24lb. I thought SE4 has similar beef compared to the SE5.


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