Howell Test Fixture (sm)
Optional for Howell SkiBindings — but suggested.
Howell Test Fixture (sm) demonstrates and calibrates the unique lateral-heel settings for ACL-friendly Howell SkiBindings — which bindings uniquely feature an additional, lateral-heel release mechanism.
(( Lateral-heel release is not rotational: no boot can pass laterally thru the side-lugs of a turntable / pivot heel. This is why turntable / pivot heels can cause ACL, MCL, meniscus, and tibial-plateau injury. Diametrically the opposite, lateral-heel release — together with the special lateral-heel settings that are calibrated through the use of the Howell Test Fixture — ACL, MCL, meniscus, and tibial-plateau injury can be mitigated.
Photo 1. Howell Test Fixture bolted to bench.
Photo 2. Howell Test Fixture firmly holding alpine ski-boot.
Photo 3. Ski held only by the binding; binding held only by the boot; boot held only by the Howell Test Fixture.
Photo 4. Howell SkiBindings Setting Recommendations Chart for all 3 modes of adjustment:
(1) torsion-about the long-axis of the tibia / lateral-toe settings;
(2) forward-bending-moment / forward (upward)-heel settings;
(3) lateral-heel pre-settings (abduction-(lateral)-force / abduction-moments).
Photo 5. Howell Testing Specifications — to demonstrate, and calibrate lateral-heel settings for the complete ski-boot-Howell SkiBinding system.
➡️ Made of solid, one-piece, 303 stainless-steel — the Howell Test Fixture includes 2 stainless-steel micro-fiddle v-blocks and 2 high-strength, low-stretch, sailing lines. Bench and mounting-bolts not included. Wooden shipping container and detailed instructions are included. Total shipping weight including wooden shipping container: 11 pounds. FOB Granby, Québec, Canada.
Howell Test Fixture and related test-method rely on a combination of …
A— … standard torsional-torque setting recommendations (DIN / ISO 8061);
B— … Howell SkiBindings toe-pieces calibrated to a specified torsional-torque from point #1;
C— … user-applied lateral-force to Howell-specified-positions at the back-half of the ski. See photo 5.
This special test-method provides comparison of the tested lateral-heel settings to the Howell specified lateral-heel settings. See resolution of deviations, below.
Biomechanical Technology Concept.
The specified measurement-metric is the position of the applied-abduction-(lateral)-force on the ski. The position where abduction-force is applied to the ski is biomechanically-based on the vertical-distance from the base of the ski (at the projected-axis of the tibia) to the center of a skier’s knee (the ‘abduction-lever-arm’) — transposed between the mid-sole-mark on the boot to a Howell-specified zone on the back-half of the ski. (The off-set between the boot’s mid-sole-mark and the virtual, vertical-axis-of-rotation formed by the toe-cup of the binding is automatically factored into Howell-recommended setting-specifications.)
💎➡️ When the specific position of an abduction (lateral) force that is applied to the back-section of the medial-(inside)-edge of a ski has a corresponding abduction-lever-arm (“abduction-lever-arm” = the lever-arm between the base of the ski and the skier’s knee) that is longer than the distance from the projected axis of the tibia to the specific position of the applied-abduction-force on the ski (the ‘tibia-torque-lever-arm’ — the heel of the binding must release laterally before the toe of the binding releases — to truncate the high magnitude of the abduction-moment (located at the center of the knee) relative to the lesser-magnitude of the torsional release-torque about the long-axis of the tibia.
In this way, the lateral release threshold of a special, additional, laterally-releasing heel can be adjustably-set relative-to industry-standardized torsional-torque settings that are produced by the toe-setting of the binding together with the given boot sole length.
Practical Workbench Practice.
It’s not always practical to measure the distance from the base of the ski to the center of a skier’s knee. Therefore, we provide a special chart that biometrically estimates the length of the abduction-lever-arm for a given skier — to represent the transposed-position of a specific ‘Transition-Zone’ onto the back section of the ski — based on skier weight, gender, average boot-sole thickness under the heel, and stand-height of Howell SkiBindings — including a ‘margin-of-safety and a tolerance for friction. ‘See photo 5.
The margin-of-safety and the tolerance for friction are automatically imbedded into the Howell-setting-specifications based on the ‘remaining-distance’ from the boot’s mid-sole-mark to the virtual-pivot formed by the radius of the toe-cup. This ‘remaining-distance’ also automatically provides for variation in boot-sole length. See photo 5.
Howell lateral-heel setting specifications apply ONLY to Howell SkiBindings.
Testing to validate Howell-specified lateral-heel settings can be accomplished in minutes.
Testing should take place every 30 skiing-days or before the beginning of each ski season, which ever is first.
Howell Test Fixture is primarily intended for ski shops — but can be purchased and used by any skier, too.
Howell Test Fixture is also useful to demonstrate how ordinary 2-mode alpine bindings have no possibility of providing ACL (or MCL, meniscus, tibial-plateau) friendly skiing at any setting.
Detailed Test Method:
(1) All three visual indicators (lateral-toe, forward-heel, lateral-heel) on left and right Howell SkiBindings should be ‘pre-set’ according to the ‘Howell SkiBindings Recommended Pre-Setting Chart’ (see photo 4) — which lateral-toe and forward-heel pre-settings conform to DIN/ISO 8061 for ordinary 2-mode binding function. This beta chart (photo 4) will be updated prior to October, 2023.
No standards apply to Howell SkiBindings lateral-heel settings because this is an additional non-pre-releasing mode of release not provided by other alpine ski-bindings.
Boots must conform to ISO 5355 — the main international alpine ski boot standard. Boots must not have metal inserts for ‘pin-bindings’ ‘Pin-bindings’ are hardly “tech”: they can cause high-energy, multi-fragment, tibial-plateau fracture and high-energy spiral-tibia fracture expressly because pin-bindings have no lateral elasticity, and because the positions of pin-bindings’ lateral pivot-points and forward pivot-points are biomechanically incorrect for human musculoskeletal integrity. See Ettlinger, C., Bahniuk, E., A method for the testing and analysis of alpine ski bindings, J Safety Research, 1980, Vol. 12, No. 1.
(2) Firmly affix the ski-boot to the Howell Test Fixture by tightly cinching both sailing lines with each of the micro-fiddle v-blocks.
(3.a) Measure the distance from the base of the ski to the center of the skier’s knee (the ‘abduction lever arm’) — measure along the side of the lower leg — then transfer that same numerical distance to span from the boot’s mid-sole-mark to the back-half of the ski — to mark the position of the Transition-Zone on the inside-edge of the back-section of the ski. The size of the Transition Zone is defined by one point that is located 4cm beyond the transferred position of the ‘abduction lever arm’; the other point is located 4cm less than the transferred position of the ‘abduction lever arm’.
— OR —
(3.b) Select a Howell-recommended Transition-Zone from the Howell Lateral-Heel Settings Chart. See photo 5. (BETA — not for use with any 3-mode bindings other than Howell SkiBindings. This beta chart will be updated prior to October, 2023).
If both methods (3.a and 3.b) are used to generate Transition-Zones on the back-section of the ski — select the Transition-Zone that is closer to the tail of the ski. This closer Transition-Zone becomes the ‘proper’ Transition Zone.
(4) Mark the range (both points) of the proper Transition-Zone on the ski.
(5) Attach the ski to the boot while the boot is securely held by the Howell Test Fixture.
(6) Secure the ski at 2-points through the use of your own ‘limiter-lines’ to block the range of motion of the released ski to prevent injury to the person conducting the tests. One connection-point should be located near the tip of the ski; the other near the tail of the ski. The 2 connections should be decisively-held at both points on the ski — but the length of lines should be slightly slack to prevent force from entering the ski by the 2 preventer-lines until immediately AFTER release has occurred. The other ends of the 2 (or more) limiter-lines should be securely attached to the ceiling and/or walls.
(7) Slowly apply, by a gloved-hand, lateral (abduction) force to the inside (medial) edge of the back-section of the ski at these 2 points:
(7.a) At a point that is 1-to-2cm greater-than the far-end of the marked Transition-Zone — to cause lateral-toe release;
(7.b) At a point that is 1-to-2cm less-than the shorter-end of the marked Transition-Zone — to cause lateral-heel release.
(8) If lateral-toe release AND lateral-heel release do not take place as described in points 7.a AND 7.b (both conditions) do NOT change the lateral-toe settings. Do not change the forward heel settings. Do not change the correct forward-pressure setting. Change ONLY the additional lateral-heel settings in Howell SkiBindings — provided, however, that no change on the lateral-heel visual-indicator is greater than 2 lateral-heel visual-indicator numbers.
(9) If a change of more than 2 lateral-heel visual-indicator numbers is required to cause the function that is specified in points 7.a AND 7.b — a list of ‘Troubleshooting Actions’ is provided in the Howell SkiBindings Operations Manual to correct the function of the ski-boot-binding system. (The few problems that arise are typically with the boot ... and can be easily resolved ... for example, by removing mold-flashings or contamination on the boot sole.)
(10) If, after applying the Howell specified Troubleshooting Actions, the functions in points 7.a AND 7.b are still not occurring — the binding, the boot, or both — are defective and/or incompatible with each other … and should be returned to Howell SkiBindings (and/or to the respective ski-boot company) for warranty replacement.
In the unlikely adverse-scenario of point #10 — Howell SkiBindings are likely remaining in compliance with ordinary 2-mode alpine binding function (DIN / ISO 9462): ordinary 2-mode workshop testing procedures (see ASTM ski shop practices) can verify ordinary 2-mode release compliance. However — ACL, MCL, meniscus, tibial-plateau friendly skiing may be adversely compromised, just as those anatomical-structures are always compromised with ordinary 2-mode alpine bindings.
Using the Howell Test Fixture is simple and fast once the above methods are understood.
Use of the Howell Test Fixture is optional with Howell SkiBindings — but suggested.
Howell Test Fixture is based on 20-years of intensive biomechanical research conducted by Rick Howell — peer-reviewed and approved by bona fide scientific committees at major international orthopedic / engineering / skiing safety / skiing science / conferences ...
International Society for Skiing Safety (ISSS) Pontresina, Switzerland, 2003 (presented by University of Montréal biomechanical engineering researchers based on a 2001 grant-application written by Rick Howell (Canadian — Industrial Research Assistance Program (IRAP / PARÉ) grant): final outcome published in Journal of Medicine and Science in Sports and Fitness:
St-Onge N, Chevalier Y, Hagemeister N, Van De Putte M, De Guise J. Effect of ski binding parameters on knee biomechanics: a three-dimensional computational study. Med Sci Sports Exerc. 2004 Jul;36(7):1218-25. doi: 10.1249/01.mss.0000132375.00721.7a. PMID: 15235329.
Several key outcomes from the above research have been importantly corrected and significantly improved in the following research venues investigated and presented 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; ISSS-Serre Chevalier, France, 2022.
International Medical Society for Skiing Safety (SITEMSH) Flachau, Austria, 2014; SITEMSH-Inawashiro, Japan, 2016; SITEMSH-Barcelona, Spain, 2018; SITEMSH-Serre Chevalier, France, 2022.
International Olympic Committee (IOC) World Conference on Prevention of Injury and Illness in Sport, Monaco, 2017, and again in Monaco, 2021 — abstracts peer-reviewed, approved, and published in British Journal of Sports Medicine:
Br J Sports Med 2017;51 (4): p. 331
Br J Sports Med 2021;55(Suppl 1):A1-A188
Br J Sports Med 2022;0:1. doi;10.1136/bjsports-2021-IOC.367corr2
European Society for Knee Surgery, Arthroscopy and Sports Traumatology (ESSKA), Barcelona, Spain, 2016; and ESSKA-Virtual (originally organized for Madrid, Spain — became virtual due to the pandemic), May, 2021.
International Society for Science in Skiing (ICSS), Voukatti, Finland, 2019.
The biomechanical technology behind ACL-Friendly Howell SkiBindings and Howell-specified lateral-heel settings is actually quite simple (quite simple — for structural engineers) …
During ‘Slip-Catch’ or ‘Phantom Foot’ events, both ends of a shaped-ski do not slide-out — thereby producing a single ‘centroid-vector’ (center of effort) located near the center of the long-axis of the ski. The lateral-component of the centroid-vector is not sensed by ordinary 2-mode alpine ski bindings because this component is located close to an ordinary 2-mode binding’s axis of torsional-rotation (near the center of the radius of the heel-cup, or near the center of a pivot-turntable heel). This scenario has no lateral lever-arm within the workings of an ordinary 2-mode ski-boot-toe-heel-binding system: in this scenario, lateral toe release of an ordinary 2-mode step-in binding is extraordinarily high and can cause ACL, MCL, meniscus and tibial-plateau injury. Even worse, toe release in this scenario with a turntable-pivot heel is impossible.
In this same loading-scenario, the same lateral-component of the centroid-vector acts over the length of the tibia, plus boot-sole thickness, plus binding stand-height, plus ski thickness — to produce an enormous abduction-lever-arm — thus producing an enormous ‘abduction-moment’ (lateral overturning-moment) located in the center of the knee. During this loading-scenario the ACL, MCL, meniscus, and tibial plateau become the focal-points of the large abduction-moment — and these anatomical structures become the weakest links within the kinematic-chain of the ski-boot-binding and human: the ACL, MCL, meniscus, and tibial-plateau become over-stressed at a magnitude that is lower than an ordinary 2-mode binding can release — irrespectively of a low ordinary 2-mode binding lateral-toe release setting: a child’s toe-setting will not provide release before injury to an adult’s ACL, MCL, meniscus and/or tibial-plateau — if the magnitude of the lateral-component of the centroid-vector is large enough (see magnitude data within ‘Part-2’ of the ‘Release’ sub-section within the ‘Tech Info’ tab of the Menu. The magnitude of the lateral component of a centrally-positioned abduction-force can be far less that the skier’s body weight to cause injury to the above-noted anatomical structures.)
🚧 As described above — ordinary 2-mode bindings have a blind-spot during the same loading-scenario that produces a maximal abduction-moment (lateral overturning moment) in the center of the knee where the ACL, MCL, meniscus and tibial-plateau are located.
➡️☀️ However, a 3-mode binding with additional, non-pre-releasing, lateral-heel release (also with the special lateral-heel settings that are specified herein) can read and react-to the lateral-component of the centroid-vector that’s generated by shaped-skis during high-magnitude Slip-Catch or Phantom-Foot events. Lateral-heel release — set according to Howell specifications — stands directly within the kinematic pathway of abduction-loading that would otherwise compromise the structural integrity of the ACL, MCL, meniscus and tibial-plateau.
☀️💎☀️ This special non-pre-releasing 3-mode binding is ONLY Howell SkiBindings.
🔑 Key to this positive breakthrough — 3-mode bindings with additional lateral-heel release and specially-tuned lateral-heel settings MUST NOT pre-release.
🗽 Only Howell SkiBindings uniquely provide key biomechanical technology to block pre-release without high settings.
Anti-pre-release independently of settings is uniquely and decisively provided by Howell SkiBindings by ‘decoupling’ each of the 3-modes of release (decoupling each mode from each other) AND by decoupling each mode of release from the ‘skiing control-modes’ that do not need to release (such as, the edging — or roll — mode). See ‘Retention’ and ‘Edge Control’ sub-links in the Menu. Each of the 3 modes of release within Howell SkiBindings are a separate system (3 separate springs; 3 separate cams; 3 separate adjustments). Each of the 3 modes of release in Howell SkiBindings uniquely function independently without adversely effecting each other.
Further, and completely uniquely, all 3 separate release-cams within Howell SkiBindings are wide off-center knuckle-joints that filter-out high compressive-force produced by ski-flex (‘filter’ — from each of the other modes of release). Ski-flex can cause pre-release in all other bindings — including in newly-announced competitors’ bindings — unless they have elevated settings. Again, elevated settings block necessary release. Howell SkiBindings uniquely do not need elevated settings to provide anti-pre-release.
Still further, each release-cam within Howell SkiBindings operates in a way that is not adversely-influenced by edging.
Other bindings do not provide these functions and designs because only Howell know-how has refined them during 4 decades of research, development, testing, testing and testing — including 20 years of testing specifically-focused on ACL-friendly function.
Lastly, Howell SkiBindings accomplish these functions — simply. ‘Simple’ translates to durable and reliable. All Howell-developed products (5 worldwide #1-selling high-tech sports products) embody robust function together with simple design.
(( Additional lateral-heel release, together with special lateral-heel settings, can also limit torsion about the long-axis of the femur — thereby limiting adverse loading on the femoral condyles, proximal-femur, and hip. ))
Howell Test Fixture:
100% 303 stainless steel: 7.75-pounds.
Shipping weight: 11-pounds.
Lifetime Limited Warranty.
Return to the top of this page to order.
Howell SkiBindings, Inc.
P.O. Box 1274, Stowe, Vermont 05672 USA
‘Howell Test Fixture’ (sm) is a Service Mark of Howell SkiBindings (sm).
Copyright © 2023 by Howell SkiBindings, Inc.; Howell Product Development Holding, Inc.; and by Rick Howell. All rights reserved.