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Meidjo 3.0 release testing

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  • #46
    I think it also has to be accepted that some of this is just good luck or bad luck either way, and differences in bindings, fitness, skill, speed, snow conditions, etc... are all just factors that can change the odds a little. They give measurable differences in injury rate with a large enough sample, but for any one skier, it's partly luck. I once broke through some snow while almost stopped, hit a buried tree, flipped over, and wound up upside down with most of my weight hanging from one ski. Felt the ski slowly torquing my leg, and was probably about to hurt my knee, when I was able to reach up and flip the heel throw on my tele binding and escape. Could have been an injury on everything except a heel throw tele binding! Pro skiers crank their bindings to crazy settings, and some of them have a lot of surgeries and some go their entire career with no injury. Some is just luck.

    Just to clarify, I think it's awesome what jasonq and others here are doing to improve safety. In a perfect telemarking world, we'd have heavy-duty inbounds tele bindings with reliable release, and really light backcountry bindings that might overall provide comparable safety to light AT bindings, and to get there we need people to do this kind of work. But for now, some is just the risk we assume, just like some of us will go solo in the bc in the right conditions and others will not.
    Last edited by xmatt; 23 April 2023, 11:56 AM.


    • #47
      Originally posted by bahboric
      Has anyone ever tried to mount some binding (Meidjo, 22d) to a plate that would fit in a 7tm binding? I've wondered if that might be a way to get releasability?
      i did look at it while i was on the couch. it could work. see pic of some cad i still have. that is a dynafit superlight toe mated to the top of a cut down 7tm toe box. or at least mated in cad, no place to screw it in. it would end up taking a custom mount plate. Also, the 7tm release plate is mounted on the ski for the 7tm toe box, and the superlight toe positioned to put the boot in the same location as if it was a 75mm/7tm toe box. they don't mate up well front to back. so, either shift the mount plate on the ski or use something more like the voile SS side throw 2 pin toe.

      Click image for larger version  Name:	7tm.jpg Views:	0 Size:	33.5 KB ID:	122824

      and obviously i never got around to figuring out pivots/springs/etc. but clearly some sort of TTS with typical voile LT carts would be easiest.

      one thing to note is the front and back tabs of the toe cage are not in the same plane. if i was to make a custom plate, i probably would have also made a custom mount for the ski to move them into the same plane. And then by that point, the only original part left would be the red release housing!

      i didn't go this way just because the 7tm's were no longer available new, or were about to be. And now, they are even hard to find used. At the time the TR2 was still available, and appealed to what i wanted more.

      that said, 7tm is still a good platform to build on, or just ski if you like 75mm and more neutral bindings. I happily skied 7tms for many years after they came out. (happily after i did a lot of anti ice work on them!). I was 50/50 whether i should just buy up the few pairs of new 7tm sti powers left and just ski them stock.


      • #48
        I mocked up TTS on a Voile CRB plate. It would have been janky as the binding parts are wider than the Voile plate which means either designing a new plate or making an adapter. I gave up and sold the Voile stuff when TR2 TTS showed promise. The idea of a semi-releasable binding mounted on a releasable binding also bothered me, both from an engineering simplicity standpoint and the associated weight, stack height, etc. Mounting Meidjo on anything is basically a non-starter due to the footprint, stack height, number of screws etc. of Meidjo.

        Also, this is a suspicion as I never skied CRB or 7tm, but I suspect those bindings wouldn't hold up to a powerful setup (stiff/active springs, heavy boots). 7tms were apparently very neutral and I think CRB was more targeted towards light tele, which is why it had pre-release problems when people started using stiffer springs and larger boots. Again, based only on my experience with TR2, I think if you put a resort-focused binding on either platform the release (or retention) would get less reliable. And if you just want a releasable BC binding, TR2 TTS is a shorter path to the goal.


        • #49
          xmatt, pretty much agree with all that.
          We like to think we can control stuff (which, to some degree, we can), but sure seems like there is a lot of randomness in life.
          To be clear, I don’t subscribe to a fatalist perspective on life…

          I used to think that every choice represented a fork in the path of life, each one leading to different outcomes.
          It’s pretty trippy, if you think about it.
          At age 21, decide to go skiing one day, or not.
          Ski day leads to you being on Mars at age 56.
          Not skiing leads to a dead end life at 56 in Wichita, Kansas, with a wife you want to divorce and three kids who hate you.

          I’ve come up with a new model.
          My life is a straight path, from birth to death, passing through all this random sh!t that is just spinning around in the universe.
          Some of the random stuff is consequential, some not.
          I spilled my coffee, oh bummer.
          I broke my ankle, bigger bummer.
          I bought 10,000 shares of Amazon in 1997 for .08¢ share (don’t I wish).

          I’m just along for the ride (with too much time on my hands at the moment)…
          Last edited by Stephen*; 23 April 2023, 04:15 PM.


          • #50
            Been wanting to post update on this…
            There are at least two thought paths here: one is “recovery progress”, the other is “what happened, and why.”

            Progress is good. Of course frustrating to not magically be 100%, but every day seems a little better. Lots of advice received, some followed, some not. Could I be more diligent? Yes, but, well, …
            ROM, swelling and loss of leg strength are the remnants. Focusing on improving.
            Realistically, it sounds like a multi-month process. The real test will be 6-9 months out and % of recovery.

            As for “What happened, and why?”
            Just listened to a Blister podcast on bindings. It just drove home the basically unrealistic hope for “safety.”
            It almost doesn’t matter what binding or system.
            Any retention setting that avoids undesired pre-release has the potential to also not release under certain conditions that will cause injury. The example of having someone knock you over getting on/off the chairlift and suffering a joint or bone injury.
            Podcast here:
            47:00 to 53:00 caught my attention, but there are other sections, also.
            One along the lines of: I make sure not to catch a tip on the groomers when I’m skiing DIN 15.
            (I tend to listed at 1.50 to 2.00 X speed to get through them faster.)
            Another comment that caught my attention was sort of along the lines of the frog in a pot of gradually warming water (not sure if that is true or an urban legend). Anyway, the sort of drift and unrealized assumption of risk because a system or standard has become accepted by the general skier population, over a long period of time.
            That’s probably much less true here.
            But the reality is that we’re affixing long levers to our feet with less than perfect safety release systems, and our joints and bones are sometimes not able to survive the forces these levers generate.

            I’m not downbeat about all that, it’s just true.
            Last edited by Stephen*; 29 May 2023, 02:57 PM.


            • #51
              Originally posted by Stephen*
              But the reality is that we’re affixing long levers to our feet with less than perfect safety release systems, and our joints and bones are sometimes not able to survive the forces these levers generate.
              that is the unfortunate truth.

              Also, on the topic of becoming comfortable with risk. When the signal is a binary event, you did/didn't get hurt, and one result is infrequent, the statistics don't work well with human psychology. for example, i skied about 1000 days without gettting hurt. using my first 1000 days to predict the odds of getting hurt on my 1001st day, 0%, yet i still got hurt. confidence bounds on non-continuous distributions...

              and despite it all i continue to ski, because, well, its worth the risk.


              • #52
                A Norwegian study put the rate of injury at 0.9 per 1000 ski days. US studies at major ski hills rate a little higher than 2.0 per 1000 days. This is a gross injury rate. The majority of injuries (well over half) occur in people under the age of 30 because inexperience and high risk behaviour on the slopes.

                Thinking of risk based on the number of times an activity is done (ie. gross injury rate) isn’t correct. It’s like saying that if you’ve flipped a coin “heads” four times, the next toss will almost certainly be “tails”. The odds of a coin toss are always 50:50, no matter how often it is done. Rolling a dice is the same deal… a 1:6 choice of rolling a six every time a single die is tossed.

                So the gross injury rate is the same every time you ski. The potential for actual injury will rise when the conditions change… much in the same way that a die might roll “6” more consistently if it is “loaded” with a weight that affects the roll.

                If conditions exceed skill or fatigue and age enter the equation, the risk of injury rises. Those wishing to mitigate risk, therefore, can do so by staying in good shape, undergoing periodic skills refresher training, knowing when to get off the hill etc. This is why some skiers go their entire lives without injury.

                Otherwise, it’s just the luck of the draw, toss of the coin, roll of the dice etc.


                • #53
                  exactly. if i remember my statistics correctly, if the actual injury rate was 1/1000 (which is actually an unknown), and is a binary value, i think you needed 45,000 data points to have a reasonably tight 90% confidence that the injury rate was between X and Y. Meaning after taking 45,000 data points, 90% of the time, 1 would have been between X and Y, and 10% of the time it wouldn't. Take another fresh 45,000 data point, get a different X and Y, but that same 90% relationship. The exact case i remember was slightly different, so it might not be exactly 45K data points to get a 90% confidence bound, but it is way more than 1000 for a 1/1000 binary event. more data points, the closer X and Y are together, ie the better the estimate of the population mean based on a subsample, the fewer data points, the farther X and Y are apart. my 45k above came from what at the time i believed was enough data points to get X and Y close enough together to be a useful result.

                  but how this interacts with human psychology is that you cannot rely on only your experience to estimate the risk (where risk is X in 1/x chance of getting hurt), it takes more data points than you can provide yourself. of course, that is not how human brains work. we know better. statistics is a lie, and it only applies to others. I'm special.

                  the dice example is good, but to judge risk based on only personal experience, but you don't know how many sides are on the dice, and rolling a 1 means you get hurt. but you only get to roll the dice 200 times. Then decide how risky your next day is based on the number of 1's rolled. doesn't work. it turns out the dice has like 1000 sides, but you don't know that, and until you actually role a 1, you can't even estimate it.

                  this is the type of thing you can over think. i know.


                  • #54
                    Originally posted by jtb
                    I...CRB was more targeted towards light tele, which is why it had pre-release problems when people started using stiffer springs and larger boots.
                    Sort of. Turns out the problem was generally with plastic tele boots. As you know, the soles of 75mm PTB's become "permanently" rockered over time. Slide the duckbill under the toe bar of the binding, the heel is lifted. When the heel is flattened out, there is an upward force at the toe. In a CRB this created an upward force on the release mechanism that made it prone to pre-release. In the final 2-3 years of the CRB's manufacture Voile accounted for this and the pre-release issues were mitigated, but the change to CRB's pre-release reputation remained unchanged. Sales continued to languish and Voile stopped making 'em.

                    ain't no turn like tele!