Alpine Boot Guide

Ensuring you have a fully compatible ski set up is crucial for proper safety and performance of your gear. This includes ensuring your boots are compatible with your bindings. 

The most important factor to consider for ski boots is comfort. Making sure the boot fits snuggly around your foot without any pinching or cramping is a must, as any small discomforts you may feel while trying on the boots will be amped up to 11 when you're out on the hill actually skiing.

In addition to the fit, you should also look out for the compatibility between your boot and your bindings, and the boots stiffness. Both of these will be discussed in much more detail down below.

By the end of this guide you should have a good idea of what you as a skier need out of your boots and what to look for when gearing up for the season.

Boot Fitting

There are a few different numbers that will go into your fit, the two important ones are Mondopoint size and last.

How does sizing work?

Ski boots use a specific sizing system called Mondopoint sizing, which is simply the length of your foot in centimetres. Although you can roughly translate street shoe size to Mondopoint, it is best to avoid this. Many people aren't wearing properly sized street shoes, and the sizes aren't always consistent. Alpine boots require a fairly precise fit, since flying down a hill is a bit more demanding than going out for a stroll.  

One specific feature of Mondopoint is that half sizes are identical to the full size in every way aside from the insole. For example, a 26.5 and a 26.0 have the exact same shell and liner, the only difference being the insole on the 26.0, which will be thicker than the insole of the 26.5. It is also possible that rather than a thicker insole, the 26.0 will have a piece of felt underneath the insole to achieve the same effect.

The added thickness of the insole raises the foot up and essentially reduces the length and volume of the boot to achieve the half size fit. This saves a ton on cost for manufacturers, allowing them to make half the amount of shells and liners needed for a full size run.

Last refers to the width of the toe box, ranging from around 97 to 107. Alpine lasts do roughly match up to street shoe lasts; 97-98 is about an A or B, 99-103 is about C or D, and anything over 103 is around an E.

How should they fit?

Ski boots should fit pretty tight. You want a snug fit to ensure good power transfer, but you don't want the fit so tight that you lose circulation or start getting pressure points anywhere on your foot. The fit should be consistent all around your foot and leg, and your heel should not lift at all when walking. Heel lift can cause some very painful blisters. Your toes should just barely touch the end of the liner. 

The fit of the boot is going to be the tightest when you first try them on in the store. Alpine liners are almost all heat moldable, meaning they will stretch out and conform to the shape of your foot after a few days of riding or after having them heat moulded at your shop. This is one of the advantages to buying over renting, your boots will have a custom fit to your foot, which makes for a very comfortable boot.

How is volume different than last?

The volume of the boot is referring to the overall height and width of the toe area, whereas last is only referring to the width of the toe area. High volume boots are better suited for people with taller than average feet (sometimes due to having high arches) that might hit the top of a regular volume boot, causing pressure points on the top of the foot. Some boots these days come in a few different volumes, such as the Tecnica Mach Sport which comes in low volume, mid volume and high volume.

Can I go to a smaller boot?

Depending on your ability, you may want to go down a half size or even a full size from your actual measurement. Beginners usually stick with their actual measurement, intermediates might go down a half size, and advanced skiers might go as far as a full size down. 

The reason for this being that tighter boots are able to transfer power more quickly, giving a better feeling of responsiveness. The downside is that the boot will most likely be less comfortable and more cramped the further you stray from your actual measurement.

Boot Flex

The flex, or stiffness, of your boot plays a very big role in the performance of your setup. This stiffness refers to how hard or easy it is to bend your ankle while wearing the boots. Flex ratings start around 50 and go up to about 130. Low flex ratings are intended for beginner skiers who are descending cautiously and at a slower pace. Higher flex ratings are intended for more advanced skiers who go fast and aggressive. 

Men's Flex	Women's Flex	Stiffness	Style	Speed	Ability
70-90	50-70	Soft	Gradual, more gentle descents, just cruising down green and blue groomed runs.	You're going a bit slower than the other people on the hill.	Beginner
90-110	70-90	Average	Exploring most of the mountain, faster blue runs and dabbling with single black diamonds.	You're keeping up with most people on the hill but still getting passed by a few hooligans.	Intermediate
110-120	90-100	Stiff	You're a strong confident skier looking to challenge yourself with black runs.	You're one of the hooligans flying by pretty much everyone.	Advanced
120+	100+	Very Stiff	You're sending it off the biggest jumps or bombing down double black diamonds.	You're crushing everyone at race-level speeds.	Pro

This table is just a guideline for skiers who are an average height and weight. Skiers who are a bit heavier or lighter than average may go up or down in boot flex. Women's boots also tend to be a bit softer than unisex boots to accommodate their lower average weight.

Park skiers are also going to choose their boots a bit differently. If you spend lots of time hitting rails and boxes, a softer boot is generally preferred for more forgiveness.

Boot flex is not an official standard, meaning a flex of 100 from one brand won't be identical to a 100 flex from another brand, but they will be quite similar.

Binding Compatibility

On the bottom of your ski boots is the boot sole, which determines what bindings will be compatible with your boots. Boot soles and bindings must follow very specific guidelines for the dimensions and function, as improperly set up gear can cause serious accidents. For this reason, alpine gear MUST be set up by an authorized dealer. Waxing is the only alpine service you should do on your own. There are two standards for boot soles, ISO 5355 and ISO 9523.

ISO 5355 Boot Soles

ISO 5355 (also known as "alpine boots" or "DIN boots") is the traditional alpine boot sole and comes in two types, Type A (ADULT) and Type C (CHILD). If an ISO 5355 boot has tech inserts on the boot, it will also fit tech bindings.

ISO 9523 Boot Soles

ISO 9523 is made up of three main categories; Grip Walk, Walk-to-Ride and regular ISO 9523 soles. These types of boots are intended for touring and are much better suited for walking in thanks to their rockered, rubbery sole. While Grip Walk and Walk-to-Ride meet the ISO 9523 standards, not all ISO 9523 boots meet Grip Walk or Walk-to-Ride standards.

Boot Sole to Binding Compatibility

For compatibility marked POSSIBLE*, boots must have tech binding inserts on toe and heel. Compatibility is case-by-case, please contact us for specific compatibility.

For all boot and binding combinations (even those marked as being compatible) installation, set up, testing and maintenance MUST be done by an authorized/indemnified dealer to ensure proper and safe performance.

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