Shell fitting a ski boot should be treated like going to a tattoo artist: Don’t go into it drunk. No one has the same two feet, and no two people like the exact same fit. And while 10 percent want that über-snug race fit, the majority of backcountry skiers want a performance fit, one that will accommodate uphill flexibility, stave off hot spots and blisters, keep you warm and comfortable all day, and ultimately deliver the power and control you seek for the down. No matter your preferences, the single best thing you can do in your search for optimal comfort and performance is begin your search with a good shell fit.
Before getting started it’s important to always fit a boot with a thin ski sock. All liners pack out, however minutely, every day you ski. Beginning with a thin sock ultimately provides a longer lifespan for the liner. For its part, SCARPA uses the highest-end, thermoformable Intuition™ liners in their boots. Light, warm and very resistant to packing out, they provide the necessary support and comfort that maximizes the skiing experience.
But, if you put your foot in a ski boot with the liner inside the shell in a store, it’s no reflection of how the boot will fit once it’s molded to your individual foot. If you assess your ski boot fit in the store in a liner that’s not molded to your foot, often the result can be buying the wrong size shell, which won’t be apparent until later. Getting around that dilemma is easy with a shell fit.
Pull out the liner and stand in the shell with your toes just touching the front of the boot (with your foot weighted). Then lean forward and see/measure how much space you have behind your heel. The ideal range is somewhere between 14 and 30 millimeters of space behind your heel. In inches, that amounts to half an inch to an inch of space, respectively. In a perfect world, there would be about three-quarters of an inch behind your heel, but rarely is it an ideal situation. However, if your heel space is within those parameters, it’ll verify if you are in the right shell (or not). (SCARPA has a fit stick for dealers that reflect these measurements and make it easy to determine (in a store) if you’re in the right shell.)
Once in the correct shell size, the second step for getting optimal fit is molding the liners. Rarely is there a perfect situation in terms of shell – people are often at one end of the spectrum or the other in terms how much space you want when you do a shell fit. If you are on the edge of going up to the next larger shell size, your bootfitter should concentrate on packing down the liners in the molding process and helping you create more space in the places you want it. If you are on the edge of going to the next smaller size, the bootfitter should do the opposite: concentrate on packing out the liners as little as possible, and possibly using fit aids like higher-volume footbeds.
Truly, there’s no substitute for an excellent boot fitter and the knowledge they bring to the process.
And, regarding the note about footbeds: They are the last not-so-secret ingredient to superior fit and performance. For the same reasons you wouldn’t put crappy tires on a Porsche, consider upgrading footbeds to a more supportive or sport-oriented model.