Backcountry Skiing Binding Alpine Mode Flex Tests — updated Late November 2010

Animation above shows the type of movement this test is designed to evaluate, known to some as ‘rolling deflection.’ All bindings move and deflect during use, the Diamir shown above is average — it has about the same amount of movement as a good quality recreational alpine binding. Please note this test if for bindings and boots that are latched into downhill skiing mode. It does not test side play of binding in touring mode, though such play may be inferred from the tests to some degree.

Here at WildSnow HQ we test randonnee backcountry skiing bindings for how solid they attach your foot to the ski (as when the cuff of the boot is tilted/pushed from side to side, otherwise known as ‘rolling deflection’).

While rolling deflection is not as big a factor in downhill control as some people think, it still makes a difference in how the binding “feels,” and definitely affects how well bindings ski on hard snow or ice, especially if your skis tend to flutter or chatter, and you need a binding that doesn’t exacerbate that effect.

Disclaimer: These results are from our own form of testing and evaluation. Other tests may produce different results.

For this evaluation I use essentially the same test rig as in my preliminary test done a while back. With the general procedure the same as detailed here, though we’re now more careful, and made tripple sure our results repeat.

Results below use dashed lines as horizontal bar graph, each dash for one unit of deflection. A “unit” is simply arbitrary and only a basis for comparison, it is not a defined measure of weight or force. What I found fascinating is that the Freeride and heavy duty Naxo Nx21 (formerly known as the “Stomp”) were essentially equal to the Marker alpine binding, while the Dynafit was quite a bit more solid than anything but the Markers, even though it appears incredibly minimal. Our “units” are a fairly fine division of the flex, thus meaning both Marker models and Dynafit are essentially the same and easily fall within any error margin in our testing. Shows you what good design can do.

Marker F12 Tour (2010/2011 model)
—————— (18 unit deflection from vertical, slightly stiffer than Duke, probably due to better AT boot compatibility of toe jaws. We were delighted with these test results. Note we don’t see any reason the F10 model would test any differently.)

Marker Duke (2007/2008 model)
——————– (19 units deflection from vertical, during some test repeats Duke and Dynafit were virtually identical.*)

Dynafit (Vertical ST/FT and radical are equal in stiffness to other Dynafit models due to toe unit providing most of the holding power direct to boot)
——————– (20 units deflection from vertical)

G3 Onyx
——————— (21 units of deflection from vertical, virtually identical to Dynafit, a bit more noticeable movement in toe and heel units when boot is flexed lead to it being rated ever so slightly below Dynafit.)

Fritschi Freeride Pro (2009 model, white, heel foot is 69 mm wide, 14 mm more than Plus model. Barely discernible difference between this and Plus, so we gave it one less unit deflection.)
————————- (25 units deflection)

Fritschi Freeride Plus (2006 model with black toe wings and red support plate under binding)
————————– (26 units deflection…)

Fritschi Freeride (2004 model with white toe wings)
————————— (27 units deflection…)

Marker M1100 Titanium alpine binding
—————————- (28 units deflection…)

Naxo Nx21
—————————– (29 units deflection…)

Silvretta Pure Freeride
———————————– (35 units deflection, measured virtually the same as other Pure models)

Silvretta Pure Performance
———————————— (36 units deflection, 07/08 model has solid carbon rails instead of hollow, should be slightly stiffer)

Naxo NX01 (All Naxo models discontinued, no more tests planned.)
——————————————- (45 units deflection…)

*Marker Duke/Baron/Tour, when used with alpine boots could possibly be somewhat stiffer than measured here, as we used Dynafit compatible randonnee boots for all tests, and the sole of most such boots does twist more than a quality alpine boot. More, the base support of Duke is wide, and is said to thus give better edge control on wider skis. We don’t know if that’s true or not, but it sounds worth considering and could mean the real-life feel of the Duke is more solid than our chart indicates. Please note that side flex of the binding in tour mode was not tested in this test. Field observations show that all Marker bindings have similar side slop in touring mode, with this limited by how the heel riser “foot” is pocketed by the base plate. When this “pocketing” works, Marker side slop is minimal, but if you push the rear part of the binding to the side and it pops out of the “pocket,” you will experience significant side slop in touring mode in situations such as side hilling. This also holds true for Fritschi, and less so for Dynafit since it’s held by the mechanical connection at the toe.

Due to inherent error in any mechanical testing system, I’m confident in saying the Marker alpine, Freeride and Naxo Nx21 bindings are all essentially equal in lateral twisting stiffness, while the Pure and Naxo NXO1 are clearly much looser. Marker and Dynafit are the clear winners overall — stiffer than the alpine binding and the Freeride!

The “units” above are for comparison only, they have no direct relationship to any unit of distance or weight. My gut tells me a difference of under 4 units would only be noticeable to precision skiers who could switch skis during the same run while using the same boots.

An interesting aspect of this study is the realization that if you use bindings with less flex, you might be able to use a more moderate boot and get the same performance as with a stiffer boot and flexy binding. All you stiff boot lovers might want to keep that in mind when considering Dynafit.