Why Shape Matters

In last week's post, we looked at the important of choosing the correct size ski boot.  Today we are going to focus on boot shape. Many of the common problems related to discomfort in ski boots stem from a mismatch between the shape of the boot and the shape of the leg/foot. Many people have variations in their foot shape like bony prominences or small anatomical peculiarities that make it necessary for them to have some customisation done to increase their comfort and performance. 

For ski boots to be comfortable and perform optimally,   there must be a certain degree of compatibility between boot shape and foot shape. Incorrect shape can lead to many of the painful conditions that our bootfitters regularly encounter in their clients.

Boot shape is a highly personal thing: Some skiers want ultimate performance and are willing to forego a certain amount of comfort to achieve this by squeezing their feet into a smaller, narrower boot that will provide ultimate energy transmission from leg to ski. On the other hand, some skiers are happy to forgo a certain amount of performance to achieve a higher level of comfort. Going further with this, there are also individual tolerance levels that come into play; some people simply don't feel or distinguish discomfort in the same way that others do, or they have conditioned their feet due to many hours in ski boots.   

It is very difficult to perfectly match the shape of boots to each foot, as the manufacturers make a standard mould, and for this reason we often customise the boots to further match the individual shape of the foot. 

Many of the models that we carry in stock now have customisable shells, making it further possible to provide the ultimate in customisation. See our page on boot fitting options. 

Some common Foot/Boot Shape considerations:

Foot/Toe Length: People vary in the length of their feet and individual length of the toes. They may have longer first or second toes or they may have all toes of closer length to each other.

Toe Box Shape: The shape of the boot toe box should match the overall curve and shape of the toes as a whole. A couple examples might include a pointed shape vs a squared-off shape: The pointed shape might have a longest second toe and other toes that each fall sharply shorter in length compared to the other, producing a situation where a more tapered toe-box is better. Alternatively, the person with toes thar have a squared-off appearance due to less variation in toe length will require a boot that is more squared-off at the toe box, or may indeed need a slight modification to make the shell wider in key areas.

Width: All boot models fit slightly differently in width. Often the overall width of the boot is advertised and classified as an overall last size. Some boot company websites display last sizes in millimetres. As a general rule, boots classified in last size 98mm or narrower may be recognised as a narrower fit. Boots ranging from 99mm-101mm are medium and anything 102mm or above fall into the wider fit category. 

There are no hard and fast rules with regards to what last size one should ski in, however for general comfort with maximum performance, a closer fit is desirable.

Arch Height and Instep: The amount of space provided over the instep of the foot is a very important consideration. There are various anatomical structures over the dorsum (upper surface) of the foot, which require the boot to fit correctly to prevent impingement and pain.

If the boot is too tight over the dorsum, then the skier may experience symptoms that are due to nerve, and blood supply/return impingement. It is also common for people to have bony prominences over the dorsum, which rub against the tongue of the shell. These problems may be combated by appropriate selection of boot shell and liner combination along with further modifications if needed.

If the boot is too roomy over the dorsum of the foot and anterior ankle, then people may experience muscle and tendon pain, shin pain and soft tissue problems, from excessive rubbing and movement as well as incorrect conformity of the curve of the boot with the position of the feet.     

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Ankle positioning: Boot manufacturers will often place a small indent in the position where they envision the ankle bones to be positioned in the boot. Due to anatomical variation, every skier's ankles will be slightly differently positioned in their boots, meaning that sometimes these simply miss the spot, or are so far off so as to cause a problem. There is also often a hinge point in the boot with rivets close to the ankle bones that can cause a rub. The combination of correcting footbeds/orthotics, the choice of most appropriate shell and further modification as needed can overcome these issues.  At the front of the ankle it is important that the boot bends in concordance with how you foot bends - this is crucial to prevent lower shin bang!   

Heel contour and retention: Heel retention is a desirable aspect of a well fitting boot. The heel retention in ski boots is achieved through a combination of the shape of the contour inside the shell, as well as materials used in the liner to effect a good heel hold. All boot brands have different combinations of these in the various models.  An often overlooked circumstance is the fact that behind the ankles, either side of the heel is where a considerable number of anatomical structures exist: The main nerve, arteries and veins as well as the tendons all pass by the heel and into the foot. For this reason it is very important that the boot fits well in this area! Not too tight, not too loose. It is important to note that for anatomical/mechanical reasons, it is sometimes impossible to keep the heel from lifting, regardless of how firm the boot is in this area. In this case, modifications can be made to help combat this problem. 

Forward Lean:  The amount of forward lean or angle that the boot is set on  compared to the surface the skier is standing on plays a significant role in your skiing style. Thiswill be further discussed in next week's post about Flex, however, for some people the forward lean is an important consideration: People with limited amount of natural ankle flexion, or people who are just learning to ski might want less forward lean in their boots. On the other hand, skiers who are likely to be flexing their ankle a lot in their skiing action, such as bumps skiers or instructors might prefer a boot with more forward lean. There are some circumstances where the forward lean of the boot is a crucial consideration in the overall comfort and performance.

Upper Cuff Volume: Narrow, slimmer-legged people require boots with less volume in the upper cuff and/or more padding. People with wider, more voluminous calves/lower legs often require lower cuffed, wider fitting boots in that area. 

Boots can easily be modified to provide extra padding or more room around the calf area provided that  the overall starting shape is within acceptable limits.  

Tune in next week for our article on understanding ski boot flex. 

Choosing The Correct Boot Size

The correct boot size is one of the most crucial things to get right!

While shape and flex are  important factors when choosing the correct ski boot, for this article we will focus on size considerations. Having the wrong size may lead to many problems and ultimately the premature need to have new, correctly sized boots fitted. Incorrect sizing from another retailer or boots purchased online is the number one problem encountered by our boot fitters.  

There are many considerations to be made depending on the shape of the foot and the skier type as well as personal preference, however, as a general rule, the boots must be as close to the correct size in length as possible. Ideally the skier will have just enough toe room to keep warm and prevent the toes from pressing into the end of the boots. Quite often your ski/snowboard boot size will be smaller than your shoe size.

When a ski boot is brand-new, the liners have not been fully moulded to the contour of the shell, and so it is very common for people to perceive the out-of-the box fit as too small. All good bootfitters will double-check the available room that your foot has by removing the liner and placing the foot in the boot shell. This enables them to examine the interface between the foot and the interior shell of the boot, taking into consideration not only the length, but also the width and height of the boot, as this ultimately determines the fit.

Other considerations:

1. Your foot size may change with added orthotic support. 

Your foot type can also have some bearing on the right size for you: Some people's feet can splay significantly without innersole support. The addition of a custom footbed/orthotic can often significantly alter the size of the foot due to splay-reduction to the point where a smaller size may be more appropriate.   This is a consideration any master bootfitter will take into account after assessing your feet.     

2. Not all boot brands and models have the same sizing standards! 

Most boot companies display the sizes of their boots in mondopoint, which is a standardised measurement system, however, there is slight variation from brand to brand and model to model which makes physical assessment of the foot in each boot a necessity. In some circumstances, you may have a foot which suits two different sizes depending on the different models. 

3. Ski boots are often made in full sizes

Ski boots generally change their shells in full sizes. Most companies make boots that go up a full size for each change in sole length (the actual length of the plastic shell from heel to toe), ie 26/26.5 = 305 mm, next size up 27/27.5 = 315mm, 28/28.5 = 325mm etc. This means that essentially there is little difference in half sizes in ski boots.  Some brands chose to split the half sizes, ie 27.5/28= 320mm, 28.5/20=330mm etc.