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Sudden Catastrophic Rim Failure on a Kris Holm 24

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  • Sudden Catastrophic Rim Failure on a Kris Holm 24

    While riding my stock Kris Holm 24” at the Milwaukee Unicyclists meet in Red Arrow Park this week, the edge of the rim spontaneously separated. I initially thought that the tire bead had snapped or that the fork had failed since there was a loud “SPROING” sound and a sharp piece of metal was poking into the inside of my calf. Upon looking closer I could see that the side of Kris Holm rim had almost entirely separated from the unicycle. I am still a novice level rider and have never taken any vertical drops with it. The tire was always filled to the maximum recommended pressure and I had been riding for about 20 minutes on flat concrete beforehand.

    Has anyone ever seen something like this before or know what caused it? Also, should I buy another Kris Holm rim or is there a stronger rim I should try? Unicycle.com is currently out of stock on the Kris Holm 24 inch rim. I have attached a picture of the failed rim below.
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  • #2
    That's a pretty old rim. It's actually a bike rim and if you look closely at the section which is still intact you'll see a brake wear indicator line. These rims always used to 'peel' like this. I've had it happen several times to me, although it was always when gapping stairs or something.
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    • #3
      Originally posted by Cyclophobia View Post
      While riding my stock Kris Holm 24” at the Milwaukee Unicyclists meet in Red Arrow Park this week, the edge of the rim spontaneously separated. I initially thought that the tire bead had snapped or that the fork had failed since there was a loud “SPROING” sound and a sharp piece of metal was poking into the inside of my calf. Upon looking closer I could see that the side of Kris Holm rim had almost entirely separated from the unicycle. I am still a novice level rider and have never taken any vertical drops with it. The tire was always filled to the maximum recommended pressure and I had been riding for about 20 minutes on flat concrete beforehand.

      Has anyone ever seen something like this before or know what caused it? Also, should I buy another Kris Holm rim or is there a stronger rim I should try? Unicycle.com is currently out of stock on the Kris Holm 24 inch rim. I have attached a picture of the failed rim below.
      That's really unusual, the current Kris Holm rim is strong, so you could get that as a replacement, but the Nimbus Dominator2 is basically bombproof. Maybe someone on here has managed to break one, but I don't think I've heard of one breaking. I'm sure someone, somewhere, has managed to, but I haven't heard of it (I also haven't been actively looking through broken parts threads).
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      • #4
        It's actually a bike rim and if you look closely at the section which is still intact you'll see a brake wear indicator line.
        I have no idea where Kris Holm sourced his components, but this is an original KH rim with his signature embossed on it. There is no brake wear on the rim and it has never been used on a bicycle or on a unicycle with brakes. Although I have found a few references to failures like this on bicycles after thousands of miles of brake wear, I could find no reference on the internet to this kind of failure mode on unicycles.

        These rims always used to 'peel' like this. I've had it happen several times to me, although it was always when gapping stairs or something.
        Aside from the leg tangling face-splat dismount, the sharp rim splinter gouged me in a spot not far from my femoral artery. Although I am sure that any component can fail if it is sufficiently abused, this unicycle wasn't. I have a hard time imagining that Kris Holm would use inferior components or that any unicycle manufacturer would use rims that would be prone to fail in such a dangerous way.

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        • #5
          Originally posted by AJ KJ View Post
          That's really unusual, the current Kris Holm rim is strong, so you could get that as a replacement, but the Nimbus Dominator2 is basically bombproof.
          I would like to stay with a Kris Holm rim if it was better made than this last one, but I am open to the Nimbus alternative. The KH rim is $90+$26.67=$116.67 (when it is in stock) and the Dominator2 rim is $55+$26.67=$81.67 from Unicycle dot com. The Dominator is out-of-stock on the UK site but the KH rim is in-stock and only $78 shipped.

          Does anyone here have any recommendations about which would be stronger?

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          • #6
            That looks like the same model as I have. I don't do big drops or much hopping but I have ridden it over many miles of rough terrain, tree roots, ruts and rocks, and I have never had that happen.
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            • #7
              Originally posted by AJ KJ View Post
              That's really unusual, the current Kris Holm rim is strong, so you could get that as a replacement, but the Nimbus Dominator2 is basically bombproof. Maybe someone on here has managed to break one, but I don't think I've heard of one breaking. I'm sure someone, somewhere, has managed to, but I haven't heard of it (I also haven't been actively looking through broken parts threads).
              No, that's usual on the old KH rim (KH2005 model), a friend of mine got the same issue but less impressive than yours !
              Last edited by bouin-bouin; 2017-05-01, 03:53 PM.
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              • #8
                Originally posted by Cyclophobia View Post
                While riding my stock Kris Holm 24” at the Milwaukee Unicyclists meet in Red Arrow Park this week, the edge of the rim spontaneously separated. I initially thought that the tire bead had snapped or that the fork had failed since there was a loud “SPROING” sound and a sharp piece of metal was poking into the inside of my calf. Upon looking closer I could see that the side of Kris Holm rim had almost entirely separated from the unicycle. I am still a novice level rider and have never taken any vertical drops with it. The tire was always filled to the maximum recommended pressure and I had been riding for about 20 minutes on flat concrete beforehand.

                Has anyone ever seen something like this before or know what caused it? Also, should I buy another Kris Holm rim or is there a stronger rim I should try? Unicycle.com is currently out of stock on the Kris Holm 24 inch rim. I have attached a picture of the failed rim below.
                Very impressive! It looks like this was the rim model that had a score down the middle of it, which turned out to be a bad idea, though I've not seen quite as spectacular a failure as this.

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                • #9
                  As others have stated that's a known problem with that particular rim, but I don't think we have seen any that seperated quite that much before.
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