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Real Heel vs 2nd Heel Apples to Apples

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  • Real Heel vs 2nd Heel Apples to Apples

    I finally got around to doing and apples to apples compare of the exact same binding with both a real heel and 2nd heel attachment to settle for myself how different they really are vs how different the binding designs that use one vs the other are. Recall that i also wrote a rather simple model to graph binding activity given spring rates, attachment points, etc. My goal was not to figure out which boot attachment point was better or worse, just how they differ in a direct compare, and to help validate my model. The binding parts i used allowed for a moving the cable exit, and i tried a forward and a backwards position. See pictures. I ensured the exact same preload on the springs in both configurations. for those that have been around a while, yes that is a rotte/chouinard 411 front throw.

    here is what i felt. pivot forward, not very different with the pivot forward. more different with the pivot backwards. In both cases, with the 2nd heel, more active (as defined by moment required to raise increase angle of boot to ski) with the heel low (~0-40 degrees), less active with the heel high (~>50 degrees). this was much less noticable with the forward pivot than the rearward. I think it is this more initial activity, less final activity that people like.

    this sensation match up well with my model. The model says forward pivots in the the 40's that i prefer, they are nearly the same. in the 50-60mm range it seems a lot of people like, it is a noticable, but not huge difference. As the pivot moves back into 60-70 mm that some prefer, the difference become much larger. see graph. each pair of red and green lines is the exact same everything, except for where cable attaches to the boot.

    does this mean that the same more initial activity, less final activity cannot be done with a real heel attach? yes, no, maybe. it means 2nd heel naturally falls more in that space. But using caming surfaces (lower initial cable pivot, higher final cable pivot), higher rear attachment, and spring rates, i am able to tune a design that can behave the same. However, 2nd heel has a wider design space for that profile. Also, i used a 26.0 TXP, which is the largest small size binding. A smaller size boot would trend more towards the heel attach since the 2nd heel is relatively closer to the real heel. Same deal with a 26.5 boot, crossing over to the smallest large size binding would put the 2nd heel closer to the real heel.

    so after all this, yeah, i don't think i will be doing any 2nd heel designs since for my prefered activity curve, it is basically identical to the true heel, and with the true heel i can run F1, F3, or NTN in the same binding.

    Click image for larger version  Name:	apples.jpg Views:	1 Size:	267.8 KB ID:	90259Click image for larger version  Name:	apples2.jpg Views:	1 Size:	155.0 KB ID:	90260
    Last edited by Dostie; 18 March 2019, 07:09 PM.

  • #2
    Love the science jasonq!

    Maybe I’m not like most people, but I do prefer the initial engagement to be softer, and the binding easier to walk around in. And then I like it to ramp up and 'more to be more' in the business end of the binding’s travel when your knee is bent. So, with your examples I see this is more possible with the attachment at the heel.

    Meidjo seems to have achieved a nice progression that I liked (it has been a while since I skied it though). The unique thing about the setup there is the rods are curved and not straight. Perhaps this creates this effect?

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    • #3
      Jason, This is very good work and I appreciate all the testing and analytics that you do. I like you ski in 25.5-26 MP boots and this explains how I’m able to get a very similar feel from my Meidjo, Outlaw and TTS bindings. The Meidjo being most active with a 56mm TV pivot vs 48mm for both the Outlaw and my TTS bindings. The Meidjo and my TTS have a slightly higher initial activity off the deck and the Meidjo is more progressive in ending range activity with the 56mm pivot.
      Thank you for this data!
      Function in disaster, finish in style.

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      • #4
        Little help, Jason.... I don't see the adjustability of the pivot point. Seems like it would require un-pictured groove-plates to bolt behind the toe-claw, sending the up-bend of the cable more or less back. Also curious what the units of the vertical axis are and what/how you measured them. (How did I miss this!!)

        EDIT---thank you for the explanation here:
        https://www.backcountrytalk.com/foru...8427#post98427
        Last edited by Charley White; 31 December 2019, 02:27 PM.
        nee, Whiteout

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