Ski Boot Sole & Ski Binding Compatibility Guide

Why Does Ski Boot & Binding Compatibility Matter?

The interface between ski boots and bindings is the single greatest factor affecting the safety of your ski setup. The job of any ski binding is to keep your boot securely attached to your ski until just before it injures your knee or leg. To accomplish this, companies have come up with a variety of different ski boot sole standards, and binding designs that work in concert with them to provide consistent and safe release. These different standards exist because of the different intended uses for boots, from inbounds riding to alpine touring. 

Not all ski boots are compatible with all ski bindings. Using a setup with non-compatible components increases the probability that your skis will not release properly, creating the potential for serious injury. That's why it is important to make sure your ski boots and bindings are compatible and safe. In this article, we'll break down the different boot standards on the market, what they mean, and which bindings they’re compatible with.

While ski boot sole and binding standards are an important part of the ski/boot/binding equation,  factors like adjustment, wear, and maintenance can also affect release. Worn soles, salt and dirt from exposure on a ski rack, and structural damage to the bindings themselves can all have a negative impact on consistency of release. Because of this, we recommend having your boots and bindings mounted, adjusted and release-tested by a qualified ski shop before use, and checked on a regular basis.

Ski Boot & Binding Compatibility Chart

	Alpine Bindings	GripWalk Bindings	MNC Bindings	WTR Bindings	Sole.ID	Tech/Pin Bindings
ISO 5355 - Alpine DIN	✓	✓	✓	✓	✓	✓¹
ISO 9523 - Touring			✓		✓	✓¹
ISO 23223 - GripWalk		✓	✓	✓	✓	✓¹
Walk To Ride (WTR)			✓	✓	✓	✓¹
Non-Compliant Touring						✓

1. Must have tech touring inserts

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Ski Boot Sole Standards and Trade Names

There are five main ski boot sole types, each with a set of dimensions that are designed to work in specific types of bindings. As of July 2021, the International Standards Organization (ISO) defines three types: ISO 5355 (Alpine), ISO 9523 (Touring), and ISO 23223 (Improved Walking e.g. GripWalk). Non-conforming touring soles found in ultra light touring boots and Walk-to-Ride (WTR) soles are not defined by an international standard.

ISO 5355 Alpine (DIN) Soles

The most common boot sole norm for inbounds ski boots is ISO 5355. Often called a "DIN" or "Alpine" sole, it is designed with a flat profile and hard plastic where it contacts the binding for better power transmission and smooth, consistent releases from alpine bindings. ISO 5355 soles will work in a wide variety of bindings including traditional alpine bindings, MNC bindings, and GripWalk bindings. 

ISO 9523 Alpine Touring Soles

The second established sole standard is ISO 9523, developed for touring boots with rockered rubber soles that sometimes do not include an AFD (Anti-Friction Device) pad. These boots can and usually will have tech fittings, and will walk much better than flat ISO 5355 soles. Most dedicated touring boots meet the ISO 9523 standard.

Within the ISO 9523 group, both GripWalk and WTR soles meet the ISO 9523 standard, so they'll work in any binding designated for ISO 9523 boots as well as bindings that specifically call out their sole type in the model name. Salomon/Atomic/Armada "MNC" bindings, Marker "Sole.ID" and "ID" bindings, and Tyrolia "AT" bindings are compatible with all ISO-defined sole types. 

ISO 23223 GripWalk Soles

GripWalk has become ubiquitous over the past several years and is now featured on a wide variety of boots, including rental boots. Featuring a slightly rockered sole, many inbounds and "crossover" (inbounds/touring) boots are now coming with GripWalk soles because they offer a very consistent release pattern, but provide better traction and a more natural walking stride than Alpine soles. As of July 2021, GripWalk soles are defined by the standard ISO 23223 and are compatible with bindings that display the GripWalk logo or name, as well as MNC (Salomon/Atomic/Armada), ID (Marker) and AT (Tyrolia) bindings. Ski boots with GripWalk soles may or may not come with tech fittings.

WTR (Walk to Ride) Soles

Like GripWalk, WTR soles were meant to bridge the gap between the pure alpine ISO 5355 standard, and the touring ISO 9523 standard. They offer a consistent release pattern, and more traction and sole options than pure inbounds boots. As of 2019, the ski industry has adoped GripWalk as the standard for "Improved Walking" soles on both hybrid and alpine boots, and WTR is being phased out. If you own a boot with WTR soles and need a binding, look for the letters "WTR" in the product description or printed on the binding itself. Standard alpine ISO 5355 bindings or Alpine/GripWalk bindings are not WTR-compatible. 

Non-ISO 5355 Alpine Soles

True alpine competition boots, designed for high level athletes, often come with very thick soles that do not meet ISO 5355 standards. These soles are meant to be planed and/or canted before use to fit the individual athlete's stance requirements. If you purchase such a boot, it will have to be modified to meet the ISO 5355 sole definition before it is skied.

Non-Compliant Touring Boots

Many fast and light touring boots fall outside of those four main standards. In the interest of touring efficiency they have shorter, more rockered soles, smaller toe and heel lugs (or no lugs at all), and other non-standard shapes. These boots do not meet the ISO 9523 touring standard, instead their tech fittings fit the universal tech binding standard. These non-standard boots should only be used in low tech (pin) bindings. They will not work with any of the bindings mentioned above, including hybrids like the Salomon Shift and Marker Duke PT.
 

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Ski Binding Standards

Ski bindings are also tested for compliance to ISO norms, ISO 9462 for Alpine Bindings and ISO 13992 for Touring Bindings. All alpine bindings on the market comply with ISO 9462 standards. In general, frame touring bindings and tech bindings with elastic travel in the heels are tested for compliance with ISO 13992 but lighter tech models with no travel at the heelpiece are not. Adding to the confusion, binding manufacturers have invented proprietary names for binding models that accept a wide range of boot sole types, making it hard for the consumer to decipher the compatibility issue. Here is a breakdown of the most common ski binding standards and tradenames:

Alpine Bindings (ISO 9462)

Traditional alpine bindings meet a standard called ISO 9462, which specifies performance parameters for the binding and dimensions for the boot. If a binding is not designated as MNC, GripWalk, or WTR compatible, it will only work with ISO 5355 soles. You may be able to fit other sole standards into it, but it will not perform safely or consistently.

Touring Bindings (ISO 13992)

Touring bindings are certified to a similar, but different standard, ISO 13992. Frame AT bindings, hybrid touring bindings, and some tech bindings will be certified to this standard. A wider range of sole types is allowed, including rockered rubber walking soles without an AFD plate, and the interface for tech binding systems is defined.

MNC Bindings

Multi Norm Compatible bindings from Salomon, Atomic or Armada will work with Alpine (ISO 5355) soles, Touring (ISO 9523) soles, GripWalk, and WTR soles. MNC bindings are your best bet if you want your binding to work with the widest variety of boots possible. Examples of MNC bindings are the Salomon/Atomic/Armada Warden series, and the Shift bindings. These bindings can be adjusted to ski with any of the aforementioned boot soles. The Shift will only tour uphill with boots with tech toe fittings.

Sole.ID Bindings

Sole.ID (or simply "ID") is Marker's most versatile binding platform. Much like MNC, Sole.ID is compatible with Alpine, Touring, GripWalk and WTR boot soles. It's also available in a wider range of bindings, from the 11 DIN Squire all the way to the 18 DIN Jester Pro.

Please note that Atomic Hawx Ultra XTD boots equipped with WTR soles (2019 and older models) are not compatible with Sole.ID bindings. Models equipped with GripWalk soles (2020 and newer) are compatible.

GripWalk Bindings

Bindings designated for compatibility with GripWalk will work with Alpine (ISO 5355) and GripWalk boot soles. Non-GripWalk ISO 9523, WTR and non-standard touring boots may fit into GripWalk bindings, but they will not perform safely or consistently.

WTR Bindings

WTR bindings will work with WTR boots, GripWalk boots, and ISO 5355 alpine boots. They will not work with non-GripWalk or non-WTR ISO 9523 boots, or with non-standard touring boots.

Pin or Low Tech Bindings

Any "traditional" low tech pin binding (two pins in the toe, two in the heel) will work as intended with any boot with tech fittings. The dimensions for the width, depth and placement of tech fittings is standardized, regardless of boot sole type. Bindings in this category may or may not be certified to ISO 13992 (touring bindings standard); if they are they will have a spring loaded heelpiece to allow for ski flex.

Non-Standard Pin Bindings

Some modern pin bindings have ditched the heel pins in favor of a more robust mechanism, reminiscent of an alpine heel. Examples include the Marker Kingpin, Fritschi Tecton, Dynafit Beast, and Trab TR2 bindings. In general, any ISO 9523 boot with pin fittings, including GripWalk and WTR boots will work in these bindings. However, the Beast and Trab may require an adaptor plate or a specially molded heel with fittings. The Salomon/Atomic/Armada Shift bindings, the Marker Duke PT bindings and the CAST System are special cases, and require tech toe fittings for skinning but not tech heel fittings for skiing down.

Though some non-standard touring boots will work in these bindings, others will not, so it's important to make the determination on a case-by-case basis - ask a certified binding technician if you have questions about a specific boot/binding combination.

 

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Ski Boot & Binding Glossary

Rockered Sole

Traditional ski boot soles are flat, which enhances power transfer and aids in consistent release. However, with the growth of backcountry skiing, more and more boots feature rockered soles with a curved profile under the forefoot and grippier tread patterns, allowing the skier to walk much more efficiently and with greater safety.

AFD

AFD stands for Anti Friction Device. When it comes to boot and binding compatibility, the AFD is a critical part of the binding. AFD's are commonly made of non-stick material and/or move on bearings or rollers, which allows smooth and consistent lateral movement to avoid injury. Many AFDs are adjustable for height, which allows the binding to work with multiple boot sole standards.

ISO

ISO is the International Organization for Standardization. It’s an independent, non-governmental organization that develops consensus-based international standards essential for quality, safety and efficiency. For example, when a boot sole is labeled “ISO 5355”, this means it is compliant with a strict rule-set (dimensions, test methods and material requirements) identified by the ISO as being important to alpine ski boots.

TÜV

TÜV (Technischer Überwachungsverein) is a global testing, certification, inspection and training provider that is often used by manufacturers to certify their products to an existing International Standard defined by the ISO. For example, when a brand claims their binding is DIN or ISO-certified by TÜV, it means TÜV (typically TÜV SÜD in München) has tested the binding and certified it to retain and release a ski boot at industry-approved levels (the DIN and ISO standards are identical).

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