WildSnow Dynafit Lab — Homework Handed In

All this talk of Dynafit toes opening while skiing got me curious. After seeing the way ATK provides configurable tension in their toe unit by inserting small disk shaped springs, I got to thinking, could a similar mod be done to a Dynafit binding? And just how much could the binding to closing force be increased? (Disclaimer: This is only an instructive experiment, not a recommended modification due to unknown wear and the increased and possibly dangerous release tension this mod would create.)

Experimental Dynafit binding toe modification, arrows point to added washers that nearly doubled the closing force of the toe wings. Click image to enlarge.

So, at least sometimes, after fantasy comes action. My feet seemed to have a mind of their own as they walked me out to the mod shop. My hands seemed to instinctually find the pin punch to remove the touring lock on an old pair of classic TLT toes I had laying around. Somehow, washers of nearly the right size were found in my parts bin, though the side of one in each pair had to be clearanced so they’d fit side-by-side. I was rewarded by a nice adrenaline rush when my first experiment flew apart and went ballistic, nearly taking out the snowmobile headlight behind me. And finally, with a modified and functional toe assembled, it was amazing how after using a pair of vice grips as a lever arm I was able to compare the spring force of the modified and un-modified toe, using a luggage scale max weight memory as a dynamometer. Result: sticking the washers in there nearly doubled the amount of force it took to open the toe.

Dynafit toe modifications

Using a luggage scale as a dynamometer, key is I added a long lever arm to the binding using a pair of vice grip pliers.

Okay, if anything this little exercise might give all of you a better idea of what keeps that binding closed on your foot, and how those forces could vary. As for increasing this force in the binding retail version, like any machinery design change this would involved consequences. For starters I’d imagine more closing force would cause more wear on the boot toe fittings and the binding pins. It would also require re-calibrating all the lateral release tension numbers and perhaps even changing the lateral release mechanicals in the heel unit of the binding. Expensive stuff for the manufacturer. But you never know, we’ll see what happens over the next few years.

Note: One valuable thing I learned from this experiment is that the small green (other colors on other models) plastic parts do show some wear after lots of binding use. Wear or manufacturing size variations in these parts could reduce the amount of toe wing tension. Prior to recently, I’ve concentrated most of my seat-of-pants engineering on the Dynafit heel unit, fun to shift the microscope over the the toe.