Tinkering with Tech Toes + Axl Springs

(Editor’s Note: This is a telemark tinkerer’s system which resembles the commercially available Telemark Tech System® but only in terms of using a Tech Toe. Just about everything else is modified within the limits of a zealous but amateur home workshop. Ben did an outstanding job of creating his own version of a telemark binding using tech toes but some of the conclusions or references to TTS should be understood as creative variations but are not representative of the Telemark Tech System® sold by Olympus Mountain Gear.)

Like many telemarkers I was skeptical of the Telemark Tech System (TTS®) when it was unveiled at the 2011 Outdoor Retailer Winter Show. Being familiar with Dynafit bindings, I knew that the tech toe piece couldn’t be as robust as a standard telemark binding. By removing the heel it was essentially emasculated, becoming a flimsy toe attachment with no controls. Little did I know how two little pins could be so much more. Once the gears were rolling it was only a matter of time before I started to tinker with my own version.

Dynafit-telemark shift plate mock up

I mounted my first set of tech-toes on Dynafit-telemark shift plates. I used the extra telemark mounting holes behind the tech toe mount to locate the hold downs for the heel assembly. I made the spring assembly hold down (fulcrum) from a polyurethane shim (cutting board) reinforced with aluminum channel and I used a steel pin as the pivot point. I added a riser (more cutting board) to the Dynafit toe to improve clearance between the boot sole and the hold down, and to equalize rocker induced heel rise.

Round 1
My first version of a home-brewed TTS used the expansion cable springs from Voile’s three pin cable binding. Despite the older design, the expansion cable spring wires worked surprisingly well, providing decent spring travel and better retention than expected. Being light weight and having a convenient side closure, this style of retention shows promise in combination with a tech heel because it might allow both telemark and AT capability in the same rig.

Round 2
For round two I tried the Hardwire cartridge assembly. As expected it provided more lateral control and more activity (retention) than the expansion spring wires — similar to HH position 2-3, but still not as much as I’d hoped for. I had compromised on the fulcrum position, placing it 65mm from the tech pins to prevent maxing out the cartridges too quickly. Given longer cartridges with more spring travel, I think the fulcrum could be moved rearward an additional 5-10mm to increase activity.

A unique challenge with tech toes is that forward rotation of the boot toe is not limited by a toe box/bale, as a result it takes significant heel retention and spring travel to effectively control the boot. The real surprise was that the Dynafit toe piece held the boot much better than I’d anticipated, though I did switch it into tour mode to minimize release.

Though TTS worked better than expected I still wanted it to be more active and have sufficient ROM while under power to be a viable option for low-stance tele-skiers. The Axl’s long, stiff springs seemed liked an ideal match for that result.

Round 3

Dyna-Axl, ver. 3. Fulcrum 75mm behind Tech fittings. Better, but not good enough.

Since the Axl allows more spring travel I moved the fulcrum back to 75mm between fulcrum and tech pins (nearly identical to ‘beta’ version of TTS®). I removed the cable and spring assembly from the Axl and threaded the cable through the hold down. Unfortunately the cable was too long, barely providing any preload even with a mondo 30 boot. On the carpet it felt like HH#3-4. On snow, however, it felt like barely any retention at all. I was dumbstruck – it felt so solid on the carpet. Clearly my implementation of the Axl cable system needed further work.

Round 4

Dyna-Axl, ver. 4. Channel stock allowed Slic Pin adjustment and excellent power.

Over the summer I let the TTS ideas fade until early Fall when the bug bit again. It seemed what was needed was a way to mount the Axl cable assembly to incorporate the moveable slick pin and flex plate, this would improve the cable run and allow for a more rearward hold down. I had an idea to use a channel, not unlike the NTN frame design. As luck would have it, a friend provided some binding mounts, which, with minor modification allowed me to mount the entire Axl spring and heel assembly, from the aluminum cable retainer rearward.

In contrasting the two Dyna-Axl bindings, note that both bindings have about the same sole angle and spring compression, but the revised binding has a more forward cuff angle, greater bellows flex, and a more rounded ball of foot. I believe this is due to the flex plate allowing a fulcrum further back. Small changes can make a big difference.

An early cold snap had our local hill open in November, so it was to the hills of North Carolina that I went, Dyna-Axl in hand, just one week before Thanksgiving. The white ribbon of death was looking good all things considered, crowds were few, and the snow was firm corduroy, narrow, fast and smooth. I set the Axl slick pin in position one (least active) and started making turns. Not bad at all. Action was smooth, retention similar to an HH#4-5.

The most amazing part was that it worked so much better than the complete failure of the previous Spring. On my second run I skipped to position three (most active). Quickly I realized that this was far too active for early season turns, it felt like my heels were tied to the skis, it literally made my tips auger into the slope. So I backed off to position two (medium activity) and took a third run, and the rest is history.

In position two the Dyna-Axl bindings were still quite active, equal to an HH position 5 with stiffy springs, which is a bit much for many skiers, but just the way I like it! I proceeded to take a number of runs to get the feel of the system. Then it dawned on me: it worked, the darn thing worked! And not only did it work, but it worked incredibly well. It was as smooth as any binding I’d ever skied, it had a modicum of release, brake potential (available with La Sportiva and ATK tech bindings), it was lightweight, it had three effective levels of activity, and because there’s no toe box, there was no toe crunch or bellows collapse. I skied for three hours that day, made hundreds of turns, and it felt great!

830 g/binding or 3 lbs. 10.5 oz. per pair. Not exactly light anymore, but a good mix of uphill and downhill performance.

The real proof came at Thanksgiving when I skied three days at Brighton in Utah. It was early season conditions with thin cover, but a good base allowing for fast groomers top to bottom, some mild bump action, and a little fresh in the trees. The bindings performed amazingly well. Over a three day period I did nothing more than adjust the preload as the Axl cables and springs stretched out. I maintained the binding in position two and skied them hard. I suffered no releases, no pre-release, and no failures. I give the Dyna-Axl Two Thumbs Up!

More nitty gritty details on page 2
© 2011