Ski Kit Info clarifies the confusing world of ski boot/binding standards, with information about downhill, AT, pin, WTR and Grip Walk boots and bindings.
Ski boot and binding systems are designed provide a safe interface between skier and skis . You need to able to ski with power and control but also to release safely in a fall. This is possible thanks to standards allowing different brands of boots and bindings to work together. It can be quite confusing though so we’re here to cut through the technical fog.
SKI BINDING STANDARDS
In recent decades there have been three traditional bindings systems for attaching your ski boots to your skis; regular step in downhill bindings, alpine ski touring bindings and pin bindings.
ISO 9462 – Alpine / Downhill bindings
Regular dowhnill bindings, also referred to as Alpine bindings, adhere to ISO 9462. They’re designed to work with ski boots that meet the ISO 5355 standard. These are the bindings that most skiers are familiar with.
ISO 13992 – Alpine Touring (AT) bindings
The second type of bindings meet ISO 13992 for ski touring. These are often are referred to as Alpine Touring (AT) or frame touring bindings. To work safely with these bindings the ski boots need to satisfy the ISO 9523 norm.
Most AT bindings now work with a variety of boot sole types. This can include Alpine (ISO 5355), Alpine Touring (ISO 9523), WTR and Grip Walk soles. If your boots do not satisfy one of these standards then they may only work properly with pin bindings.
It is worth noting that WTR (Walk to Ride) and Grip Walk soles are not ISO standardised sole designs.
UPDATE June 2021
Grip Walk now has ISO certification, so is an officially standardised sole. You can find out more about this in our article on the new Grip Walk certification.
Pin / TLT / Low tech pin bindings
PIN bindings, also known as TLT, Low Tech, Tech and other names, are the go-to solution for many ski tourers. They can be a lot lighter than frame touring bindings. Also, due to the location of the pin inserts in the boots, they offer a more natural gait when skinning.
Pin bindings are designed to work with boots that have pin inserts in the toe and heel of the boot. Boots for pin bindings don’t have to meet the demands of ISO 9523.
Many boots for pin bindings look almost identical to Alpine Touring ISO 9523 boots, but may not meet ISO 9523. Always check this if you’re going to ski in different bindings. Boots typically have the ISO number on the sole.
To work safely with this binding ski boots need to satisfy ISO 9523 and have toe pin inserts
There have been many developments in binding systems in recent years. The vast majority adapted one (or more) of the systems mentioned above, so boot norms have not really changed.
BOOT SOLE STANDARDS
ISO 5355 – Alpine / Downhill boot sole
Ski boots that meet ISO 5355 (downhill) need a flat, hard area under the toe and heel. This allows the boots to release safely from the binding in a fall. Defined measurements for the shape and size of the toe and heel area ensure they work safely with ISO 9462 bindings.
ISO 9523 – Alpine touring (AT) boot sole
AT boots have a curved sole with grippy pattern in the softer rubber on the sole. Like downhill boots, there are standards concerning the shape and size of the sole and the areas at the front and back of the boot, where the boot interfaces with the binding. These all form part of ISO 9523. These boots are designed to work safely with an ISO 13992 AT binding.
Pin inserts in the boot sole
Many AT boots also have pin inserts. As long as the boot also satisfies ISO 9523 then you can use these in pin bindings and AT bindings. It also means you can use the new breed of freeride touring bindings, like the Marker Kingpin, Fritschi Tecton or Atomic/Salomon/Armada Shift.
IMPORTANT Many boots for pin bindings do not satisfy ISO 9523 – always check before you change bindings.
Walk to ride (WTR)
Rocker not as pronounced as AT sole
Salomon introduced the Walk to Ride (WTR) boot sole in 2012. This worked on an adaptation of the Alpine Touring ISO 9523 boot norm. These boots were not certified to work in regular downhill bindings.
Multi-norm or Alpine Touring bindings could work with WTR boots, as could bindings with a WTR setting.
There were a few brands that took on the WTR concept and used this in some of their boots. However, it was not fully adopted.
Grip Walk boots and bindings
For winter 2016/17, Dalbello/Marker introduced Grip Walk (GW) boots and Grip Walk ready bindings.
The Grip Walk (GW) sole shape is an adaptation of the ISO 9523 Alpine Touring norm. GW soled boots should not be used in regular downhill bindings designed only for for flat soled ISO 5355 boots.
There are some similarities though. Like downhill boots, GW soled boots have a hard, flat section in the toe and heel areas. Again this ensures the boot can release smoothly and safely from the binding.
AFD highlighted
This hard area also helps drive power to the ski. The hard plastic in the front of the sole, for example, interfaces with the anti friction device (AFD) in the binding toe piece.
Grip Walk boots have a curve to the sole, giving them a rocker. This rocker, along with a grippy rubber tread, makes it easier and safer to walk in GW boots compared to downhill boots.
Note how it curves under the ball, then flattens under the toe
Some brands went with WTR and some with Grip Walk but this was confusing for consumers and retailers.
Mass adoption of Grip Walk
On Monday 22nd January 2018 a pivotal announcement was released. Amer Sports (Salomon and Atomic) signed an agreement to use Grip Walk. WTR would therefore stop.
The beauty with this system is that Grip Walk bindings work with both Grip Walk and regular flat soled ISO 5355 downhill boots.
It is likely that Grip Walk will become the norm for almost all skiing that uses a step-in binding system. ISO 5355 could therefore be the domain of racers in the future. This could happen within the next few years.
For winter 19/20 the majority of brands have put GW ready bindings on most of their skis. Most brands also offer an after marker GW sole for many of their boots. Some models come with GW soles as standard.
It is worth noting that Grip Walk and WTR soles are not the same as Alpine Touring ISO 9523 soles. Always check with your retailer when buying new boots / skis that your ski / boot will work safely with what you’re buying.
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