How to Buy Alpine Touring (AT) / Randonnée Bindings

Great article from Evo.com.  Touring binding technology is confusing , here is an excellent article to help you sort it out.

How to Buy Alpine Touring (AT) / Randonnée Bindings

Alpine touring (also known as "Randonnée" or "AT") ski bindings allow you to lift your heels naturally while skinning uphill or moving over rolling terrain, then lock your boots down and use regular alpine skiing technique when you want to go downhill. Used in combination with climbing skins and alpine touring boots that have a hinging upper cuff, AT bindings make traveling over snowy ground remarkably fast and efficient. If the idea of skinning uphill under your own power and using conventional alpine technique to ski down appeals to you, consider alpine touring bindings.

Things to consider:

• What type of skiing are you planning to do with this binding? "Burly backcountry lines with air" is different than "fast and light, long-distance touring.”
• Do you plan to use this binding for lift-served skiing as well as touring?
• Does this binding require a specific type of boot?
• Are you willing to carry the extra weight of a heavy AT binding?
• Are you willing to accept the downhill limitations of a light AT binding?

Types of AT Bindings

AT bindings fall into two categories:

Frame Bindings - Frame type bindings have toe and heel pieces connected by a frame or rails and often work with both alpine and alpine touring ski boots.

Tech Bindings – “Tech" type bindings, often referred to by the brand name Dynafit, although there now are several brands that make tech bindings, rely on two sets of pins to hold the toe and heel in place and require a special boot. Tech bindings are lightweight because the “frame” in the system is your rigid boot sole itself. 

There’s a growing selection of both types of AT bindings, offering lots of choices in weight, function, and price.

Up vs. Down

There's compromise involved in any ski, boot, and binding system that goes both up and downhill. What's best for the up - light weight and range of motion - is at odds with what works best for skiing down, namely width, mass, and stiffness of boot and binding.

The best binding for you will vary depending on your skiing style, ability level, fitness level, conditions, and the type of touring you plan to do.

Strength vs. Weight

A burly ski combined with a heavy frame binding will ski as well as most alpine setups and be suitable for heavier skiers or those who ski aggressively in the backcountry. It also appeals to those who can only justify one pair of skis and boots for both lift-served and touring days. The downside is weight - extra pounds on your feet are slower on the uphill, which takes its toll over a long day of touring.

A very light ski and boot with a tech binding will let you fly up the skintrack but for some doesn’t provide the same downhill and release capabilities of a more robust, heavy setup. Tech bindings require a boot with molded-in toe fittings and a slotted heel plate. Some super light tech boots will only work with tech bindings, but many will work with frame bindings as well. Super light setups are appropriate people who plan to use their binding predominately for touring vs. skiing in a resort and don’t plan to catch a lot of air or ski super aggressively. They are great for long trips, spring and summer tours where deep fresh snow and crust are rare, and randonnée racing.

Keep in mind that tech binding release values appear to use the same DIN (Deutsches Institut für Normung, a German standards organization) scale as alpine bindings, but are not DIN certified like alpine bindings - the elasticity of tech bindings and the force required to cause a release, won’t necessarily be the same as an alpine binding set at the same number. 

Unlike alpine bindings which release laterally at the toe, all tech bindings currently on the market have a fixed toe and are designed to release initially from the heel in both the lateral and vertical directions. When the boot has travelled far enough out of the normal ski position, it levers the toepiece open and the boot pops out.

Which binding is for you? 

The best bet for many people is to start at the heavier end to get a feel for the sport without jeopardizing their enjoyment of the downhill. Some people simply swap their alpine bindings for AT bindings, get some climbing skins, and head out. That is, with proper backcountry safety gear and knowledge, of course.

Heavier Frame Bindings 

Heavier frame bindings like those from Marker, Salomon, and Atomic have the same sort of retention and elasticity as their alpine counterparts and use many of the same components. These bindings can be used reliably for inbounds skiing by aggressive skiers and are suitable for wide and heavy skis. A beefy frame binding and stiff AT boot can be a good choice for skiers trying to do it all with one setup, or hard charging skiers transitioning from alpine setups. Note: Not all frame bindings are certified for use with all alpine touring soles - check the manufacturer's recommendations to ensure that your boot is compatible with the binding you choose.

Lighter Frame Bindings

Lighter frame bindings from Fritschi and Marker can be the right choice for those who mix touring and lift-served skiing, want to lessen the total weight of their setup, and aren’t as concerned with charging hard and fast. These bindings can often be used with almost any touring boot and will also fit alpine boots. The step-in operation and release settings will be similar to alpine bindings.

Tech Bindings

Choosing a tech binding and boot combination may be the best choice if you plan on touring far or fast. The lighter weight and smoother mechanical action will save you energy on the uphill, and you’ll cover more ground with less fatigue. Light, smooth and less aggressive skiers can use tech setups successfully for inbounds skiing, too.

Keep in mind that most frame bindings function like alpine bindings for entry and exit (the only difference is a locking switch to convert from tour to ski mode), but tech bindings require a short learning curve - this adjustment period might not appeal to everyone, especially newcomers to touring.

Common AT binding questions:

Can I telemark on AT bindings? No. People who are already familiar with telemark technique will sometimes throw in a few tele turns with AT heels unlocked, but they aren’t designed for the stresses of telemark skiing at speed. Furthermore, AT bindings pivot in front of the toe, while telemark bindings and boots are designed to flex at the ball of the foot with a spring for rebound. 

Can I use alpine boots with these bindings? Most frame-type AT bindings have enough toe height adjustment to use with an alpine DIN boot, but tech bindings will not accept them. Also, skinning for long periods in heavy alpine boots that do not have a hinging hike mode can be quite uncomfortable.

Can I use a tech binding for my everyday lift-served skis? Maybe. If you are light, smooth and don't get much air, they might work for regular lift-served skiing, but they are not for everyone. Also, tech bindings do not meet the ISO 9462 standard for alpine binding release and adjustment, and may not perform like the alpine bindings you've been using.

Can I use a tech binding with a wide powder ski? Probably. Wide skis place more stress on the boot/binding connection than narrow ones, but many people use this combination successfully. 

Can I use a frame-type AT binding with big skis as my only setup? Yes. Heavier frame bindings often use the same release mechanisms as their alpine counterparts and are extremely reliable.

How about adapters that let me use the alpine bindings I already own? There are a few adapters that work with alpine bindings which allow you to go into tour mode. 

The SI&I CAST System - This system allows you to use regular alpine bindings for the descent, but slide in a Dynafit Radical toepiece instead of your regular alpine toe for skinning. The CAST system requires a modification to your alpine boots so that they can be used with the Dynafit toes.

The MFD Alltime Plate - Plate is mounted to your skis, alpine bindings are mounted to it, and the MFD plate hinges up and down.

The BCA Alpine Trekker - They fit into your alpine bindings and hold your boots securely while allowing the heels to lift; you remove them and put them in your pack to ski down. 

These options could be a solution if you prefer your alpine bindings with extremely high release values, don’t need to skin far, or aren’t afraid to carry the extra weight uphill.

Thanks to our friends at evo.com for the great info.