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  • Trab TR2 TTS Binding

    Background: I've been trying to find a good, simple, reliable backcountry/touring telemark setup that is also releasable for safety reasons. I already have an NTN/TTN setup (Meidjo) and like it a lot for the resort, but it's a pain for touring. Between the fiddly transitions and icing issues, I spend a lot of time dealing with the binding rather than skiing, especially because the areas where I ski have a lot of up and down. I think NTN has the best lateral/edge control, and good releasability, but all that binding underfoot has inherent transition and icing problems. I think with a lot of development these issues may eventually be solved, but the complexity of NTN bindings becomes a reliability concern. Not a big deal at the resort, but I don't want a flex plate or spring box cracking when I'm miles from help.

    TTS, on the other hand, is simple, lightweight, has less of a problem with icing, and offers relatively easy field repairs. The main drawbacks are less control with the real heel connection, and lack of reliable release. Since lighter touring boots (F1, F3) aren't as stiff as resort boots, the control difference between real heel and NTN is not as much of a concern for me when touring. Releasability is, though. There's no good solution for telemark release at the real heel, and there are only 3 tech bindings designed to release at the toe (Fritschi Vipec, Tecton, and Trab TR2). Of those, only the Trab looks to have the strength and range of motion for telemark. There's a thread on the brainstorming behind this idea here.

    When 2020 COVID/end-of-season sales resulted in some temporary discounts on backcountry gear, I jumped on a couple sets of Trab TR2 bindings and got to work. I incorporated elements of OMG TTS, Kreuzspitze, and Meidjo in this binding, while also 3D printing a bunch of my own parts. Here's the result.

    Tech Toe

    This is the heart of the binding. It's a standard SkiTrab/La Sportiva TR2 toe. The only modification is related to entry/exit. The TR2 toe is meant to be engaged and disengaged with a completely free heel. As a result, the toe pins only open enough to slide the boot back to exit. I wanted the ability to exit the binding with a telemark heel and/or tech alpine heel engaged, which meant I had to modify the TR2 toe to spread the pins a bit wider. This required grinding the bottom of the release lever, as its travel is limited by the ski surface. In this picture, you can see the stock toe on the left, modified on the right:

    Click image for larger version  Name:	uDPb7-4sSs_Zig6EXMYzW9bLJV0HOJCTcGC_4V_N9bomei40P01OGA2CzkpT9lz8xmWGv7BrLKO3smIbbaxXXHQs96iqzjNLSQZKDb7dgIJLlGizfvbV3n6cpN2QlehgnjPW7kLCsuE=w800.jpg Views:	0 Size:	169.5 KB ID:	105352

    Grinding down the release lever made it structurally weak and broke through the pocket where you're supposed to press your pole, so I designed and 3D printed an extension for the release lever. It screws into the stock lever and includes a new, deeper pole pocket.


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    Springs and Pivot Block

    With soft/lightweight touring boots and skis, I like softer, less progressive springs. I chose the Voile long-travel touring spring cartridges, and a relatively neutral pivot block location. I used the OMG pivot block. The middle pivot is 55mm back from the toe pins. Furthermore, since the TR2 toe pins are quite high (36mm) due to the release mechanism, I designed and 3D printed a 5mm riser for the pivot block, with an ice breaker and slanted edges molded in. I also put anti-ice tape on the top surface. I can't find the link but I remember Dostie writing that 1mm in additional pin height above the pivot plane is like 2mm back in pivot position, so I wanted to bring the height differential between pins and pivot back down to what a standard tech toe would be (most are around 28-31mm).

    The pivot block riser also prevents bellows droop by supporting the ball of the foot. It's debatable how much this matters in telemark mode, but it saves energy in touring mode and keeps heel pin gap from changing in alpine mode. Another nice side effect of the pivot block riser is that it gave me more options for connecting the springs. Specifically, I really like the "axle" that Kreuzspitze uses to connect Voile Hardwire rods. Why? A few reasons:
    1. The Kreuzspitze axle and Voile rods are a lot more laterally stiff than the OMG pivoting rod.
    2. Voile rods are more readily available to replace in case of damage, not to mention cheap and easy to pack in a repair kit.
    3. This setup allows completely removing the rods and springs without unscrewing the pivot block, which saves weight under your feet on a long tour.
    All I had to do was grind off less than 1mm from the sides of the OMG TTS pivot block, and the Kreuzspitze axle fit the channel like a glove. One other simple trick I used was to slide small pieces of rubber tubing over the Hardwire rods. When installed, you can push them up against the axle to keep the rods from coming off, even in a big crash. But slide them back a little, and you can slip the rods off to remove the spring cartridges completely.

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    Heel

    This is where I applied some learnings from previous bindings I've made. First, I used a 3D printed heel throw that I designed specifically to fit the contours of Scarpa F1/F3 boots. It even has a little notch to clear the aluminum ski/walk lever on the F1 Race/Carbon, which interferes with most other heel throw designs. This heel throw uses a little metal clip to attach to the Voile heel bail. That has a nice benefit: if you attach a small neodymium magnet to something behind the heel, it keeps the heel throw and springs down when disengaged for touring.

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    Speaking of the heel piece, there's one thing about the Meidjo alpine heel that I really like. It's the only tech heel I know of that you can engage and disengage without stepping out of the toe. It sounds like a small thing, but the times I find myself wanting an alpine heel, I'm usually in terrain that's steep and sketchy enough that I don't want to step out of my binding. Since the Meidjo alpine heel is only designed to be used with the Meidjo plastic heel pad and riser, I decided to create a hybrid heel piece using the Meidjo pins/block mounted to a custom-designed post with the Kreuzspitze/ATK screw pattern. After prototyping the heel post in plastic, I had it 3D printed in stainless steel by Shapeways.

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    This solution has a few benefits:
    1. The Meidjo heel has very low lateral tension and is meant to be used in combination with a telemark heel. That means you don't have to disconnect the telemark binding to use the alpine heel, which makes transitions easier (see video below).
    2. Using a common screw pattern and heel adjuster (Kreuzspitze/ATK) means I can swap heels, remove the telemark springs and rods, and use this as an AT binding.
    3. The Meidjo alpine heel has a little slot that easily fits a small magnet, which I installed with epoxy.
    Since the Meidjo alpine heel doesn't include a heel pad or riser, I used the OMG TTS heel for those. I plugged the mounting holes and instead drilled 2 more that align with the Kreuzspitze heel adjuster -- this not only saved drilling more holes in my skis, but also means I can move the heel pad to accommodate different sized boots. I did have to grind some material off of the underside of the OMG heel to clear the Kreuzspitze adjuster.

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    Transitions

    To show the ease of transitions between binding entry, touring, climbing, telemark, alpine, and binding exit, I took a video. All of these transitions are possible with a flick of a pole -- no ski removal or even bending over necessary. This is also why I mounted the binding to Voile BC skis; for low-angle rolling terrain, minimizing use of skins and quick transitions maximize time spent moving.



    Snow Testing

    Coverage is pretty limited right now, so I've only been able to ski these on groomed runs at the resort. But the skiing dynamics were as expected -- when skied with F3's, control was comparable to Meidjo with duck-butted F1/F3's, but not as sharp as Meidjo with TXP's. I did have one pre-release at the toe with tension set at DIN 6.5. I increased it to DIN 8 and tightened the spring cartridges a bit, and had no other issues after that.

    I still need to test these in more aggressive terrain, and in the backcountry, once we get more snow. But I think the original concept has proven viable. I'll report back when I have more data.
    Last edited by jtb; 6 December 2020, 01:14 PM.

  • #2
    Very clever. The rule I learned from Dostie in my cave in Boulder was 1 mm down = 2 mm back.

    Comment


    • #3
      Nice work! I love how the cable is pinned down and out of the way of your boot heel when touring (or totally removable). You should film yourself going mach 2 into a mogul field to demonstrate how well they release. But for real, do you think something like this could make the back end of a TTS more releasable?

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      Originally posted by jtb View Post
      I already have an NTN/TTN setup (Meidjo) and like it a lot for the resort, but it's a pain for touring. Between the fiddly transitions and icing issues, I spend a lot of time dealing with the binding rather than skiing, especially because the areas where I ski have a lot of up and down. I think NTN has the best lateral/edge control, and good releasability, but all that binding underfoot has inherent transition and icing problems. I think with a lot of development these issues may eventually be solved, but the complexity of NTN bindings becomes a reliability concern. Not a big deal at the resort, but I don't want a flex plate or spring box cracking when I'm miles from help.

      TTS, on the other hand, is simple, lightweight, has less of a problem with icing, and offers relatively easy field repairs.
      This, 100%. Meidjo & Lynx are kind of do-all bindings, optimized for neither touring nor resort use. Which is fine, they're early attempts at a new kind of product, for a niche market. Hopefully with the next generation of TTN bindings, we see some specialization, simpler for touring, more robust for resort use. Right now, TTS is still the best option for touring.

      Comment


      • #4
        Dostie It seems like an article could be pretty easily cobbled together from this post and jasonq's post about his TR-2/Meidjo hybrid. People clearly want tech-tele bindings with upgraded release capabilities!

        Comment


        • #5
          BTS -- I remember that heel throw design you made. There are two reasons why I don't think that would work with this setup. First, with the Voile spring cartridges, the heel bail or springs would hit the boot and limit lateral heel displacement. A design that puts the springs underfoot, more like the BD01, might fix that. But more importantly, I think lateral heel displacement introduces pre-release problems with the TR2 toe. The time I pre-released, I noticed the OMG pivot rod was tweaked. I'm not 100% sure if that was a cause or effect of the crash, but it is not very laterally stable. I suspect that was a contributing factor. That was the primary reason I decided to use the Kreuzspitze pivot axle instead. Pivot rod flex is no longer a source of heel displacement, though of course spring tension (or lack of it) still is.

          Comment


          • #6
            So what does this binding setup Trab/TTS hybrid (with Meidjo heel) weigh? Cool project.

            Comment


            • #7
              i have yet to weight mine. just too lazy to take it off the 2x4 while i am still futzing with it.

              but based on the stock 3.0, previous POLR experience, i expect the TR2 meidjo hybrid to be about 625-650 grams a side. So not light, but not heavy. kinda middling. That is based on the TR2 toe being 250 grams, vs ~140 for a vertical toe, or 85 for a superlight. And the increased weight of my riser. And POLR with superlight and meidjo being about 480 grams. Hard to make up for the extra TR2 toe weight.

              Comment


              • #8
                Damn, and all with the pole. Garage tech has gone to a new level.

                Comment


                • #9
                  Using a common screw pattern and heel adjuster (Kreuzspitze/ATK) means I can swap heels, remove the telemark springs and rods, and use this as an AT binding.
                  I like this idea. Get extra heel posts made by Shapeways, as you pictured above, mount on your skis. Can you choose different hardness, in the steel heel post? Then buy an extra pair of toe pieces from Skimo, say Dynafit Radicals, or Ions. Now you just transfer the rotating heel assembly between your various skis/heel posts, with the toe piece mounted on the ski with QK. Heel post mounted permanently. So you only move toe pieces from one ski to another. Heel post stays on skis, transfer the rotating heel turret between skis.
                  I've often thought with AT binding ; heel turret removed, I could more easily pack my skis into my ski bag for trips to Yurp, or out West.
                  Last edited by chamonix; 7 December 2020, 12:40 PM.

                  Comment


                  • #10
                    I'm just here to post that once again, I'm amazed at the ingenuity of the posters on this board.

                    Comment


                    • #11
                      chamonix here are the weights of the various parts, measured per ski without screws and inserts. My scale is not super precise, but I sanity-checked the individual component weights by also weighing everything together, and it adds up.

                      Trab TR2 toe: 260g
                      Voile long-travel tour springs with pivot rods and heel throw: 270g
                      OMG pivot block with 5mm riser: 80g
                      OMG heel pad with single climbing bail: 35g
                      Meidjo alpine heel with custom heel post: 130g
                      Kreuzspitze 40mm heel adjuster plate: 25g

                      Total: 645g without alpine heel and adjuster, 800g with

                      Since most people probably don't care about the alpine heel, I think 645g is a pretty good number for a simple, releasable backcountry touring tele binding. It's a ~150g penalty over the Meidjo, and maybe 250g over a minimal, not-really-releasable TTS. I think my long-travel Voile springs are a little heavier than regular springs. There are definitely a few ways to shave grams off of this setup, but as jasonq said, it's a middle-weight. Not something to brag about to the gram counters, but about as light as you can get without compromising on release (TTS) or reliability (Lynx/Meidjo, i.e. making critical parts out of plastic or composites).

                      Regarding AT mode, my plan is to use the Kreuzspitze GT heels I have, increase the lateral release tension, and just use the TR2 toe. Note: I haven't tested this yet, and it may have pre-release issues. I'm hoping it's possible to set a high enough lateral release tension at the heel that it will never release before the toe, but once the toe releases, the heel will rotate to help free the boot. The nice thing about using Kreuzspitze/ATK heels is that I don't have to print another custom heel post, as they're about $50 a piece, and I like the idea of using the TR2 toe for AT (and not drilling more holes or swapping toes).
                      Last edited by jtb; 7 December 2020, 12:36 PM.

                      Comment


                      • #12
                        Originally posted by jtb View Post
                        with the Voile spring cartridges, the heel bail or springs would hit the boot and limit lateral heel displacement. A design that puts the springs underfoot, more like the BD01, might fix that. But more importantly, I think lateral heel displacement introduces pre-release problems with the TR2 toe.
                        Ah yes, of course. I guess a heel throw like that would have to be used in a configuration like the old Linken bindings. And I can definitely see how it could cause pre-release issues with the TR-2 toe. Probably best to keep the heel in place and prioritize good release up front.


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                        Comment


                        • #13
                          Originally posted by jtb View Post
                          Regarding AT mode, my plan is to use the Kreuzspitze GT heels I have, increase the lateral release tension, and just use the TR2 toe.
                          can't see why this wouldn't work. i did basically the same thing when i cranked the release setting on the M3.0 spring box so release was just the TR2 toe.


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                          • #14
                            We got a little snow last night, but the backcountry is still not skiable. So I parked behind the resort, scaled up a fire road, did some lift-served runs, then skied/scaled back down the fire road.

                            No pre-releases today (still on DIN 8). The snow was super packed/icy, and I was getting lots of chatter from my back ski, but the bindings worked fine.

                            One minor issue was that, on the way up, I had to remove skis a few times to boot through rocks/dirt. The TR2 toe entry takes some getting used to. It's easy on carpet or the first run of the day, but when there's snow packed around your toes and you can't see the pins and cups easily, it's not as automatic as stepping into Dynafit/Meidjo/etc. I figured out that resting the boot on the TTS pivot block and finding the right angle that puts the cups at pin height is a lot easier than trying to "hover" your toe.

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                            • #15
                              Quick update on these bindings after 3 months of regular use:
                              1. I was skiing in warm, wet, heavy snow today and had a pre-release at DIN 8. I'm increasing the toe tension to DIN 9.
                              2. I never used the alpine heel, so I removed it and replaced it with a magnet on a strip of aluminum (to keep the heel down in touring mode).

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                              Other than those changes, the binding has been working great.

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