Where We Tested
To test AT backcountry ski bindings, we mainly skied in the backcountry. Nothing highlights pros, cons, and comparative differences of a technical ski and mountain product like miles and hours and days out in use. In day to day backcountry skiing and ski mountaineering, we note ease of use, durability, weight, downhill performance, and uphill efficiency. Our test team includes human-powered ski guides traveling the world and dedicated lifers making their 1000th lap on the backyard stash. The breadth and depth of experience we bring to the table allows us to make authoritative field observations and to draw conclusions about the bindings' performance.
In addition to tens of thousands of human-powered feet of backcountry skiing, our test team weighed each binding, including mounting screws, on a calibrated postal scale. We also measured "stack height" and "binding delta". Both are deduced from measurements at the toe and heel piece of each binding. We measured the distance, in millimeters, from the top sheet of the ski to the center of the toe and heel pins (or their effective locations, as deduced from the fittings of the boots used, for binding systems that do not employ pins) of the downhill-mode of the binding. This is two different measurements; one for the toe and one for the heel. The average of these two numbers is the binding's "stack height" while the difference is the "binding delta". Basically, our measurements of stack height compare bindings via distance from boot to ski, and binding delta compares bindings for the relative difference in toe and heel elevation, all in downhill mode. Stack height influences lateral leverage while binding delta influences fore-aft weight distribution. Bindings are the primary determinant of these numbers, but body geometry, ski geometry, and boot angles will also influence the way your particular set-up performs.
Neither in our routine use nor our objective testing did we thoroughly assess binding release values. Both subjective and objective testing of release values are problematic. To gather enough anecdotal data on binding release stresses and characteristics involves way more crashes than our test team is ready to risk. To gather objective release data is equipment intensive and the numbers one might generate are only relevant for comparing very, very similar bindings. Our comments on release value and characteristics of tested bindings are based on a few things that are important to highlight here. The easiest bindings to review, in terms of release value, are those that are certified by a third party. ISO/DIN certification of ski bindings is a proven, established method and organization. We can count on the conclusions drawn in the process of this certification. The release characteristic of a "DIN Certified" AT binding approximate (but are not identical to) your alpine bindings. Much more difficult to assess is the release characteristics of non-certified bindings. These bindings may feature adjustable release with numbers that "look like" DIN values. If the bindings are not certified, the numbers are not "DIN Values". They might be commonly referred to as such, but they are not. Because a third party hasn't assessed them and due to the difficulties mentioned above in OGL release value assessment, any comment we make on non-certified release characteristics is based on anecdotal, small-sample-size evidence and our deep understanding of the mechanics of ski bindings.