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Trab TR2 toe with standard tech heel?

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  • Trab TR2 toe with standard tech heel?

    I'm giving a way a bit about one of my projects still in progress here...

    I got my hands on a set of Trab TR2 toes, and I have to say, I'm impressed. On carpet, they seem to work great. Step-in is easy, they have enough forward rotation to go almost knee-to-ski, and lateral elasticity and release is very impressive. When you apply lateral force, you can see your toe floating around quite a bit before the release mechanism pops out. Also, they're incredibly beefy -- pretty much everything except the mode lever and the release tab are solid metal. They're not the lightest tech toes, but I think they may be the safest. I think these could work in a TTS rig.

    But my question is about heels. I'm making a hybrid TTS/AT setup, and obviously not going to use the crazy TR2 heels. Those heels look like they are only made to release forward, not laterally. Instead, they clamp the heel solidly from the sides, and rely on the toes for lateral release.

    My question is: why couldn't I use a standard tech heel with the TR2 toes? I think the lateral elasticity of the toes may cause the boot to slide very slightly forward on the heel pins, but I think that could be solved by increasing the lateral heel retention force. I'm thinking a cranked-down tech heel can't be any worse than the Trab heel in terms of lateral retention. I also have heels with separate lateral and forward release adjustment, so I can leave the forward adjustment at a normal level and increase lateral tension.

    I know this is a bit theoretical, but wanted to see if any of the tech binding gurus here could think of a reason not to do this.
    Last edited by jtb; 8 October 2020, 12:39 PM.

  • #2
    My initial thought is that it should work fine, as long as you are precise with your mounting and setup. In other words, there is typically a little bit of slop allowable re: how far the heel prongs stick into the fitting on the heel of the boot. If you mount yours so that the prongs stick in as far as possible (without bottoming out and binding things up), I'd think you'd be fine.

    Do you plan to ski these with bellow'd boots? That could certainly eat up a lot of the slop that you're afforded. But, since you have a 3D printer, it's not too hard to make a custom puck to sit under the bellows and prevent the boot from flexing & ahortening. I​ say go for it.


    • #3

      There is a reason binding makers only allow lateral release from either the toe OR the heel, not both. I don't know the reason, but my guess is that it is too hard to calculate/anticipate release values when both ends of an alpine binding have lateral play.

      The only thing potentially worse than a non-releasing alpine binding is one that releases prematurely. Depends on circumstances.

      ain't no turn like tele!


      • #4
        Dostie - you're right, that would argue for cranking down the lateral heel release to max value, essentially making it close to fixed... or not using a lateral release toe.

        I remember from the WildSnow article that lateral toe release saves your tibia, while lateral heel release saves your ACL. It's not that I prefer my tibia over my ACL (though, maybe I do), but that the toe is the only place where TTS can release. Sidebar: I've had Meidjo release laterally at the duck butt, but only with my heel down. I don't think it would release with the heel up because the springs effectively increase the release value way above where you set it. I think the TR2 toe would release laterally with the heel down or up, as long as enough sideways force is applied. I do plan to test this a lot on on mild terrain before going down anything where retention would be critical. It's possible that pre-release with the heel up could be a problem. If that happens I'll have to switch to a conventional tech toe.

        BTS - yep, I've already made two heights of spacers for the TTS pivot block, one that goes on top of the block and one that sandwiches it. The TR2 toe pin height is pretty high, which is actually nice because you can move the TTS pivot block vertically to get more adjustment possibilities from a single mount on the ski. Though if using this as an AT binding, I'd probably use an AT boot anyway.


        • #5
          I think for that trab unit to release properly at the toe, it needs the heel fixed to act as a center of rotation. otherwise you will just wedge out like a typical tech toe. And looking at the what i have been able to find on the web about how the mechansim works, i am not sure if it will do that gracefully as it is design to release after some amount of lateral motion of both wings in the same direction. I think to make that toe release as designed, you will need to do more of a plate binding, think bomber or VP-II with a trab toe or better something more like an Iser that has been telmark-ified. without that fixed heel rotation, it will try to push the wings in opposite directions. I know the vipec does not like wedge release for this reason.

          but i have never touched one, but did spend a few weeks on the couch last winter taking a hard look at how i would make a releasable tele binding with that as the toe. in the end, i wasn't convinced enough to order a pair on risk. But if it does work without fixed rotation at the heel, i'd be happy.


          • #6
            PS there is at least one binding with lateral release at both heel and toe, search "knee binding".


            • #7
              Jasonq - the TR2 toe does wedge out like a standard tech toe, but with more force required than under purely lateral input. When one of the wings moves outward, the release tab counter-rotates slightly to pull the other wing in, and also pulls against the release spring. But if you wedge both wings out at once, the release tab can't counter-rotate, and both wings pull against the release spring via the tab, rather than partially rotating the tab. So they have to displace the spring a bit further to get free of the tab vs. when they move in the same direction. But I think this is actually good because it's easier to apply rotational force about the toe (using the foot as a lever) than lateral force displacing the toe. I think it would have been easier for them to design the binding to release with less rotational force than lateral, so I see the way it works as a feature they designed for rather than a bug.

              In TTS mode, I think the heel throw and springs should keep the heel sufficiently stable to avoid rotating the toe. After all, this is why TTS works with tech toes, when in tour mode the slightest bump causes the boot to rotate the jaws/pins apart. I'm thinking maybe a cranked down tech heel would allow it to work the same way in AT mode, but am less confident about that... but anyway, this is primarily a TTS setup and if the AT mode doesn't work, I'd be OK with that.

              My biggest concern is that, with the TR2 toe, forward pressure from the cartridge springs with the heel raised may assist lateral release once the toe gets slightly off-center, rather than that spring tension working against release as it does with a standard tech toe. But I'm confident enough that this might not happen to give it a try.

              Of course this is all speculation, but it worked well enough on the carpet for me to drill into a pair of skis. I applied all kinds of forces to my boot while in TTS cartridges and a heel throw, and the toe seemed to behave well. It didn't rotate out unless I really cranked the boot, and it did slide out laterally with a reasonably large hit.


              • #8
                Originally posted by jasonq View Post
                PS there is at least one binding with lateral release at both heel and toe, search "knee binding".
                Actually, the designer of this binding left his original partners when he felt they bought an early, incomplete design to market.
                So here is the refined design, designed by Mr Howell. Who I have met, and discussed bindings, both Alpine and Tele with quite a bit.


                • #9
                  yep, actually didn't mention them because they appear to be vapor ware. started taking deposits in 2016, and i have watched the delivery date be pushed back again, and again. just looked, and now oct 23. last time i looked it was oct 21. I get the feeling the design isn't his issue, it is the cost of tooling to bring it to market.


                  • #10
                    I have seen some reviews of the KneeBinding mention pre-release, but others say they've had no problems. I would be interested in getting my binding on some kind of jig for objective testing. Of course I don't have one and am unlikely to make one, so if anyone knows of someone who does, I'd like to explore that.


                    • #11
                      larger alpine shops have binding testers. I get if you ask around your area, a shop has one, and i wouldn't be surprised if they offer testing services. Looks like REI offers the service, and i see references to other shops too.

                      but make sure what machine they are using. for example it looks like the montana jetbond st/sk binding tester wouldn't work because it holds the heel while testing the toe. But the jetbond M would likely work because it doesn't hold the heel. the wintersteiger machine doesn't hold the heel, but when testing the toe it pushes sideways at the toe of the boot, which in this case isn't quite the same as twisting the boot with a foot. the montana machines by contrast insert a fake "foot" inside the boot and twist that. Which i think is better for your use. YMMV or YOMV.


                      • #12
                        any updates on using the TR2?

                        I was pondering a TR2 with a meidjo spring box for release at both ends.


                        • #13
                          Not really what you are looking for but Lou Dawson played a Trab Toe and a Kingpin heel-


                          Biggest speculation was potential prerelease. No real conclusions though.


                          • #14
                            jasonq updates coming shortly, just waiting on a shipment from Shapeways with some parts. I used this project as an excuse to try printing with metal, which has been interesting.

                            I also considered using the TR2 toe and Meidjo springbox, but I ultimately decided that having release at both ends was going to be too many variables to control and I'd be unlikely to have confidence in both retention and release. I ended up going with the TR2 toe and TTS heel retention, with the idea that TTS not allowing heel release is actually a feature when paired with the TR2 toe, rather than a liability when paired with a standard tech toe. I'm also adding a modified Meidjo alpine heel, just because.

                            Edited to add: TTS also simplifies a bunch of things around touring mode, underfoot real estate, and snow packing... problems which can be solved with effort, but I'm not sure it's worth the effort.

                            I did run into some challenges with the TR2 toe, which I'll document in a new thread. But overall I'm still cautiously optimistic that this can work based on carpet testing. I'm hoping there's enough snow in a couple of weeks to test on some groomers.
                            Last edited by jtb; 9 November 2020, 01:31 PM.


                            • #15
                              JTB, thanks, looking forward to it. i hear you on the variables. since TR2 toes aren't cheap to get, i'd like to know i am not wasting my money if it decide to give it a go. still might not work, but if you have TTS in a decent state of affairs that means i would likely not be throwing my money away, completely.

                              so time to keep an eye out for TR2's cheap.

                              btw, i have done a few small stainless steel parts thru shapeways (the stainless with bronze infusing version). for smaller parts i have been very happy. not as crisp on the corners or details as SLS, which is to be expected, but the dimensional accuracy was pretty decent, and for 20 bucks i got a part that would have taken me 4 hours to machine from aluminum. but i waited 3 weeks to get it... I am very curious about the SLS aluminum, but it is expensive, and i haven't had anything that would make it worth it.