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Howell ACL Vector Transposer (test device)


Optional for Howell SkiBindings, but suggested.

Available now !!

        Howell ACL Vector Transposer (sm) validates, demonstrates, calibrates the ACL/MCL-Friendly function of Howell SkiBindings. ‘Relies on a combination of the standardized torsional release torque-setting, the given boot-sole length, and the test-device’s special vector-transposition of abduction-moments — to test any complete ski-boot-binding system for ACL and MCL friendliness.  

     Recommended test-values are gender-specific.

     Apply lateral force (by hand) to the numbered-section of the test-arm according to the data supplied in the special chart. See chart in photo gallery.

     Testing is performed & completed in minutes.

     ‘Metallic-foot  is fully-integrated.

     ‘Howell ACL Vector Transposer is intended for ski shops — but can be purchased by anyone — to test and calibrate the special ACL and MCL function of Howell SkiBindings with a complete ski-boot-binding system.  Great for demonstrating how ordinary 2-mode alpine ski-bindings have no possibility of providing ACL or MCL injury-mitigation at any setting.


(1)  All three visual release indicators on each left and right Howell SkiBinding should be ‘pre-set’ according to the ‘Howell SkiBindings Recommended Release Setting Chart’ — which recommended lateral-toe and forward-heel settings conform to ISO 9462 and ISO 8061.  See chart in photo gallery.  Boots must conform to ISO 5355 — the international alpine ski boot standard (no metal dimples for AT-pin-bindings).

(2)  Fine-tune the torsional release torque toe-settings using a torque measuring device such as the Vermont Release Calibrator by Vermont Safety Research (Vermont Safety Research is NOT affiliated with Howell SkiBindings).

(3)  Set-up the Howell ACL Vector Transposer with the numbered-section positioned over the top-rear of the ski.

(4)  Select the recommended ‘Transition-Point’ from the Howell ACL/MCL-Friendly Release Chart.  ‘See photo gallery.  

(5)  Apply force (by hand) to the numbered-section of the transposer as follows:

     (5.a)  Apply lateral force (by hand) at a point 4cm greater-than the chart-recommended Transition-Point — to cause lateral-toe release;

     (5.b)  Apply lateral-force (by hand) at a point 4cm less-than the chart-recommended Transition-Point — to cause lateral-heel release.

(6)  If lateral-toe release or lateral-heel release does not take place as described in points #5.a AND #5.b (above) do NOT change the lateral-toe release-settings / do not change the forward-heel release-settings.  Change ONLY the lateral-heel release settings — provided, however, that no change in the lateral-heel release setting is greater than 2 lateral-heel indicator numbers.

(7)  If a change of more than 2 lateral-heel indicator numbers is required to cause the function described in points #5.a AND #5.b (above) — a list of ‘Troubleshooting Actions’ is provided by Howell SkiBindings to satisfy the function specified in points #5.a AND #5.b.  (The few problems that arise are typically with the boot-interface ... and can be easily resolved ... for example, removing a mold-flashing on the boot sole.)

(8)  If after applying the Troubleshooting Actions the functions in points #5.a AND #5.b are still not occurring — the binding, the boot, or both — are defective and/or incompatible.  
WARNING in this unlikely adverse-scenario #8 — Howell SkiBindings will still comply with ordinary 2-mode alpine binding function for tibia-integrity (according to ISO, DIN, AfNOR and ASTM standards) but ACL/MCL-integrity is compromised. 

     Using the Howell ACL Vector Transposer is simple and fast. 

      Use of the Howell ACL Vector Transposer is optional with Howell SkiBindings, but is suggested.

Available now !!

Biomechanical Proof

     Howell ACL Vector Transposer is based on 19-years of biomechanical research conducted by Rick Howell — peer-reviewed and approved by bona fide scientific research committees at major international orthopedic-engineering conferences ...

     International Society for Skiing Safety (ISSS) Pontresina, Switzerland, 2003 (presented by University of Montréal biomechanical engineering researchers based on a 2001 grant-application promulgated by Rick Howell.  All other venues listed below involve scientific presentations investigated by Rick Howell ) ...

... ISSS-Niigata, Japan, 2005;  ISSS-Aviemore, Scotland, 2007;  ISSS-Bariloche, Argentina, 2013;  ISSS-Cortina, Italy, 2015;  ISSS-Innsbruck, Austria, 2017;  ISSS-Squaw Valley, USA, 2019;  

     International Medical Society for Skiing Safety [Société Internationale de Traumatologie et Médecine des Sports d’Hiver] SITEMSH-Flachau, Austria, 2014;  SITEMSH-Inawashiro, Japan, 2016;  SITEMSH-Barcelona, Spain, 2018;

     International Olympic Committee (IOC) World Conference on Prevention of Injury and Illness in Sport, Monte Carlo, Monaco, 2017;

     European Society for Knee Surgery, Arthroscopy and Sports Traumatology (ESSKA), Barcelona, Spain, 2016 — peer-reviewed, approved, and published in British Journal of Sports Medicine ( Br J Sports Med 2017;51:283-412 ).

     International Society for Science in Skiing (ICSS), Voukatti, Finland, 2019;

     ... as well as at 2 forthcoming international orthopedic-engineering conferences postponed to 2021 due to the pandemic.

Biomechanical Engineering

        The biomechanical engineering behind ACL / MCL-Friendly Howell SkiBindings and the Howell ACL Vector Transposer is simple.

        During ‘slip-and-catch’ (large abduction-moment) events that are the primary cause of skiing ACL and MCL ruptures — the center of the injury-producing forces enters the ski, laterally, closely-behind the projected-axis of the tibia.  This point where the center of the slip-and-catch forces enters the ski is not sensed by ordinary 2-mode alpine ski bindings:  there’s no possibility of release, irrespectively of the release-settings.  But this same slip-and-catch abduction-force produces a large abduction-moment centered within the ACL and MCL.  

        Pop.  💥

        However, a binding with ADDITIONAL lateral-heel release can respond to the unique position of slip-and-catch forces IF properly tuned and IF the special lateral-heel release mechanism is compatible with the non-standardized geometry of the heel of the boot.  


        HOWEVER — A BIG HOWEVER — specially-tuned lateral-heel release that provides ACL and MCL friendly skiing MUST also NOT pre-release.  Howell SkiBindings uniquely provide key know-how and key intellectual property to block pre-release without high settings in all 3-modes of release (2).  Anti-pre-release is uniquely and decisively provided through 6-degrees-of-freedom Functional Decoupling between each of the 3-modes of release.  Other bindings don’t have this because Howell-patents block them unless they pay:  there’s a fair cost to reciprocate for the mountain of research that developed Howell SkiBindings, but the other binding companies prefer short-term profits (they refuse our fair offer) over the belief that all skiers deserve healthy and vibrant long-term skiing.

        The Howell ACL Vector Transposer uniquely transposes lateral force-vectors to any binding’s toe — OR heel — depending upon the location of the hand-applied-vector on the number-indexed arm;  depends on the length of the boot-sole;  and depends the ratio of the lateral toe-setting to the lateral-heel setting.  This custom tool provides a means to tune lateral-heel release within 3-mode Howell SkiBindings for ACL / MCL-friendly skiing — OR  it illuminates how ordinary 2-mode bindings cannot provide ACL or MCL friendly skiing at any setting.

        Mitigation of skiing ACL and/or MCL injury through the use of Howell SkiBindings and/or the optional-use of the Howell ACL Vector Transposer does not imply that all ACL and/or MCL injuries can be prevented.  Other less-common ACL / MCL injury-mechanisms (BIAD, backward-twisting) are NOT addressed by all Howell SkiBindings models and NOT by the Howell ACL Vector Transposer.

        100% stainless steel.  7.75-pounds.  
        Shipping weight:  11-pounds.

        Lifetime Limited Warranty.

        This is a lifetime tool.

Available now !!


‘Howell ACL Vector Transposer’ (sm) is a Service Mark of Howell SkiBindings.

Copyright © by Howell SkiBindings, Howell Product Development Holding, Inc., and Rick Howell, 2020.  All rights reserved.