AlpineTouring.Net

If you're just getting into alpine touring and backcountry skiing, it won't be long before you start to hear other skiers rave about the lightweight, minimalist Dynafit AT binding system. Long favorites of Euro ski mountaineers, rando racers (and other weight weenies), and backcountry guides, Dynafit alpine touring bindings seem to be just now breaking into the North American mass market (if there is such a thing) for backcountry skiing.

I'm a recent convert to Dynafits, and in this article I'm going to explain how they work and why you should join the Dynafit cult too.

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Most AT bindings (think Fritschi FreeRide, Naxo, Marker Duke and Baron, Silvretta, ... ) are basically plate bindings, where the ski boot is held between a toe clamp and heel clamp, which are joined by a plate (or sometimes rods) under the boot sole. The plate is attached to the ski with a pivot mechanism at the toe for touring, and the heel end of the plate can be locked down to the ski for downhill mode.

The Dynafit binding system does away with the plate or rods, and attaches the ski boot directly to the ski. At the toe, the Dynafit binding (my Dynafit TLT Vertical ST in these photos) has two pointed steel pins (green arrows in the photo below) which fit into steel socket inserts (blue arrows) molded into the ski boot toe (my Scarpa Spirit 3's in the photo). At this point, it should be obvious that not all ski boots can be used in Dynafit bindings... they must have the toe (and heel) inserts molded into the shell. The toe pins are on a spring loaded mechanism, so that pushing the boot toe engages the pins into the sockets, and pushing down on the lever in front of the toe piece (with a ski pole) disengages the pins. The springs also provide a release mechanism for the toe, although this release tension is not adjustable.
Dynafit binding toe

At the heel, the Dynafit binding has two steel pins pointing along the ski (green arrows below). These pins fit into slots (blue arrows) in the heel of Dynafit compatible ski boots to hold it in place for downhill skiing. The heel pins are spring loaded, and the tension can be adjusted to provide DIN release settings for upward and sideways release at the heel. (The up and side release DIN settings can be adjusted independently, if you have some reason to want that).
Dynafit binding heel

The photo below shows the boot mounted in the Dynafit binding, ready for downhill skiing. The pins at the toe (green) and heel (blue) are both engaged. Note that the toe lever (red arrow) is in the down position. This allows the toe piece to release in the event of a fall. Getting into the Dynafit binding for downhill mode is typically a two step process. First you push down with your toe to engage the toe pins, then you step down at the heel to engage the heel pins.
Dynafit binding in downhill mode

To switch from downhill mode to touring mode, you must exit the binding. This is done by pusing the toe lever down, which disengages the toe pins. The ski boot can then simply slide forward out of the heel pins. Next, you re-engage the toe pins, and pull the toe lever into the up position (red arrow). Moving the toe lever up locks the toe pins into their sockets for touring (otherwise you would easily twist out of the toe piece while touring). The heel piece of the Dynafit binding rotates around a vertical post mounted on the ski, and you rotate the heel pins out of the way for touring mode. In the photo below, the heel piece is in the high heel lift position ( blue arrow, more on that below).
Dynafit binding in touring mode

As mentioned above, the Dynafit heel piece rotates (pink arrow below) around a vertical post attached to the ski, and it snaps into one of four positions (the arrows in the photo point to the part facing forward in each of the positions)

1. Heel pins forward for downhill mode (green arrow below)
2. Touring mode with no heel lift (yellow arrow)
3. Touring mode with low heel lift (red arrow)
4. Touring mode with high heel lift (blue arrow, this part is sometimes called the "volcano" because of its conical shape on older versions of the binding)

Dynafit binding heel positions

So that's how the Dynafit binding works. Now what's so great about it?

1. Light weight. Dynafits are some of the lightest bindings out there. There's really nothing extraneous on the binding (no extra plates or rods under the boot sole), and that's something you'll really appreciate on long tours and for earning your turns.
2. Reliable. Every AT binding will break given enough use and abuse (although some of them have much lower thresholds than other). Dynafits have proven to be very reliable... that's one of the reasons you'll more often than not see ski guides and other backcountry professionals on Dynafits. Two of the more common failures are the "volcano" heel lift breaking off from wrenching on it with a ski pole, and the heel piece post breaking at the bottom where it mounts to the ski. Both of these points have been strengthened in the recent Dynafit TLT Vertical series of bindings.
3. Natural stride. In touring mode, the pivot point of the Dynafit binding is at the tip of the ski boot, rather than a few inches in front as with most other bindings. This results in a more natural stride motion than for example Fritschi Diamir bindings (but not quite as natural as Naxos with their "virtual pivot point").
4. Solid boot-binding attach. Alpine touring bindings can be notoriously flexy. You might think that the minimalist Dynafits would not hold a ski boot very securely, but that's not the case. In lateral flex testing by Lou Dawson at Wildsnow.com, only the extra-beefy Marker Dukes held the boot more securely than Dynafit bindings.

So what are the disadvantages of Dynafit bindings?

1. Dynafit compatible boots needed. You need ski boots with the Dynafit inserts. This limits your choice of boots, and Dynafit compatible boots are usually more expensive. (Note that Dynafit compatible boots will still work in all other AT bindings too).
2. Brakes suck. The optional Dynafit brakes just do not work as well as the rest of the binding system. They interfere a little bit with rotation of the heel piece between touring and downhill mode, and they have a tendancy to get a bit jammed with snow or ice and fail to disengage. Despite these flaws, I still use the Dynafit brakes.
3. Fewer release directions. Dynafit bindings do have DIN standard release capability, but they do not release in as many ways as a true alpine binding. If you're going to be skiing primarily on-piste with a little bit of hiking, you'd probably be better off with something like a Marker Baron (or Duke).
4. Tricky to step in. Dynafit bindings are step in, but the two step process is not as easy as most other AT bindings. It can be tricky to align the toe sockets on your ski boots with the pins on the binding toe piece. Dynafits are sometimes called "Dynafiddles" because they take some learning to use. However, as a long time telemark skier I found my Dynafits to be much easier to use than many of the tele bindings I've dealt with!.

So now that you're sold on the Dynafit system, which Dynafit binding should you get?
I use the Dynafit TLT Vertical ST, which has a DIN range of 5-10, and is often sold packaged with 92mm brakes:
Check prices on Dynafit TLT Vertical ST w/ Brakes 92mm at US Outdoor