30 Jul Choosing the Right Ski Boots

Choosing the right ski boot.

So you may be asking why am I writing about choosing ski boots? Isn’t that the job of the boot fitter in the local ski shop? Well yes, it is. But my experience over the years of updating my own boots suggests that the advice given may not always be beneficial.

Here’s my story. About 15 years ago, I decided to get more serious about my skiing. I was told by an instructor that my ski boots may be letting me down and that I should look into a more high performance style boot. At that stage, I was a competent blue and black run skier with a total of 20weeks of skiing under my belt. This included some NZ Heli skiing, French Alps, powder in North America, and most runs in Australia. I could get down anything, but I was by no means  an expert. So I went to a local ski shop in Melbourne and was fitted in a high end pair of alpine ski boots that suited a slim foot. I had $130 foot beds fitted to $700 boots. The boots felt comfortable enough in the shop and I was reassured that these flash new boots were sure to improve my skiing. I can’t say that I felt any immediate improvement. The extra stiffness took some time to adjust to, and I did play around with some minor adjustments to the forward lean angle. 12 years, and maybe 15weeks of more time on the snow, a handful of extra lessons and changing over another 2 pairs of skis, my skiing did go up a level or 2. But, I seemed to be plagued by aching thighs. Not the front of my thighs burning halfway down the hill, it was the back of my thighs. They would ache terribly while sitting on the chair lift!. The sheer weight of the boots, bindings and skis, would compress the back of my thighs as my legs hung down. I realized I needed to go lighter in weight.

Dr Victor Wilk.

The only light weight option I could find were touring boots. 3 years ago, I got my first pair of alpine touring boots (Salomon MTN Explore) weighing 1.5kgs per boot compared to the 2.5kgs of the old boots. I also had some light weight touring bindings fitted to a new pair of Volki Mantra skis. Now, the new skis aren’t that light, and their a notch stiffer than my old skis, but WOW, the difference! No more aching thighs on the chair lift for a start. Everything was easier; getting my weight forward, edge to edge transitions, control over bumps and in deep snow. I had so much more freedom in my movement. Not only were my old boots too heavy, they were just too stiff for me to ski in. This could be because I only weighed 68kg. The flex rating of my new boots was 100 (medium stiffness for a mens boot) compared to the 120 of the previous boots. Often, there is a huge variation in the given flex rating for each manufacturer. I hadn’t given this much thought since, until I recently started looking into getting new boots fitted for my wife and boys.

I thought I’d do some further research into what the ideal flex / stiffness for a boot is.  I’ve been questioning the need for heavy rigid style plastic ski boots for some time. Reading through medical research, I couldn’t find any references comparing the injury rates of stiff VS soft boots. Why does a child weighing half as much as an average adult still require a heavy clunky boot weighing almost 2kgs each? Why do snow boarders get spoilt with soft flexible boots? How come they don’t need rigid plastic boots? Yes, they have 2 feet fixed on one plank, but they still need precise edge control and similar fore-aft and side-side balance to skiing. (As an aside – it used to be accepted wisdom to ride skis over 200cm in length. Now they are getting much shorter and wider and with more shape. I think snowboarding has influenced this evolution.)  When you look into skiing VS snowboarding injuries, we find lower limb injuries are much less common in snowboarding.

The accepted wisdom is that if you’re light weight and a beginner you get a soft boot. Intermediates get a medium flex boot to transfer energy more quickly from the boot to the ski, but still soft enough to allow them some forward flex. Expert skiers get a stiff boot, supposedly for ultimate control. In Melbourne it is almost impossible to buy a soft flex mens ski boot. In the end, I had to get my Salomons imported directly, as the only ones available here were the 120 flex rated boots. For women the boot flex ratings start at about 80, but most boots sold here are in the stiff category.  Interestingly, I found while researching on google that there is very little discussion on this point. Most bloggers encouraging people to go stiffer.  The only other voice out there on the internet echoing my views is an orthopaedic surgeon in the USA.  Here’s an excerpt from Dr Ken Stone MD;

“What we realize now is that the new ski shapes make skiing so easy that stiff, heavy boots make less sense than ever. The ankles can now be used to turn the skis. This means the softer the forward flex, the more feel for the ski is possible. And importantly that with dorsal flexion the skier is able to manipulate her center of gravity more readily to maintain pressure over the arch and metatarsals as opposed to the heels. This can only occur, however, with new materials. Because it is not stiffness the skier wants it is reactivity, how fast does the boot return to its optimal shape after being flexed? It turns out that if the polyurethane is replaced with specialized nylons—such as Grilamid or thin carbon fiber skeletons—the ski boot can be made 75% lighter. It remains stiff in lateral positions but super reactive in forward and back motions. All of a sudden, the skier becomes a dancer, with quick, light motions driving their skis anywhere on the slopes.”   (https://www.stoneclinic.com/blog/once-you-go-soft-you-are-never-going-back )

I’ve been on the lookout for these “new” boots, but haven’t seen any yet. Alpine Touring boots are as close as you can get, and fortunately we are now seeing a greater proportion of these in ski shops that can still be used with alpine style bindings.

So off we go to get boots fitted for my wife and son, both are at an intermediate level, but improving. It has been interesting observing the fitting process for new boots in 3 different retail outlets, with all offering different advice. Browsing on google also yields varying advice. Boot fitters are mainly focused on finding a good fit, usually erring on the tight side, because in high performance you want absolutely no movement inside your boots. But is that the most important thing for your average recreational skier? A boot that is too stiff will result in the skier leaning too far back. In ski racing this is offset by having a boot with more forward lean putting the skier into an aggressive forward stance position all the time. There is a lot of misinformation out there as to how much flexibility you need in your ankles and almost no assessment on whether you can actually reach that range of movement once inside your boots.

Incorrect ankle mobility assessment

Here is the wrong way to assess ankle mobility from a YouTube video. In the clip, they measure the range of active dorsiflexion (pointing toes up) of the ankle with the knee straight, which is only measuring about half of the flexibility of the Gastrocnemius muscles of the calf. But when skiing we put our weight though our ankles, increasing this range through passive forces and also with bent knees. Here they are suggesting a range of 15 degrees of foot dorsiflexion.

Correct ankle dorsiflexion assessment.

Here is the correct way to measure ankle dorsiflexion. This is the simplest of 3 methods described in orthopaedic textbooks, and as it turns out, is also the most reliable. It is the easiest to use at home or at the ski shop.

• Stand with your foot flat on the floor with your knee bent.
• Measure how far you can move your big toe back from the wall without lifting your heel off the ground.

The average distance for adults is just under 10cm. With ski boots on, this is helped a little by the ramp angle inside the boots, usually about 5 degrees, but offset by the stiffness of the boots. The forward lean of the lower leg here measures about 40 degrees using a goniometer.

So how do you assess the right stiffness / forward flex in your boots?

A simple test is to stand up in both boots done up firmly with the toes of the boots against a flat wall.  You should be able to bend the knees and easily touch the wall with your knees.

Side view standing relaxed in boots with gentle pressure on tongue of boots

Side view this time all the weight on one boot and measuring the distance from the wall – you should achieve at least 5cm.

Side view bouncing up and down in both boots – you should easily reach past the vertical line from front of boots

How much ankle movement do you need to ski?

The skis. Skiers that lack ankle mobility rotate their knee inward, putting their foot into a more pronated (rolling the ankle inwards or flatten the foot) position. This flattening of your arch inside your boots can lead to pain in the foot and also the knee. The range of motion can be improved by raising the heel inside the boots – also known as increasing the ramp angle. With the assistance of an average 4 to 5 degrees ramp angle inside your boots – you only need about 25 degrees more dorsiflexion.

Most boots already put you in a position of about 15 degrees forward lean, which we can measure with an inclinometer.

The purpose of these angles is to keep you in balance and with a good centre of gravity. If you are out of balance you will struggle with your skiing.

So now is the time to get out your boots. Try them on and see what sort of mobility you have in the boots. It is also the time to start getting fit for skiing. With the advent of Covid and lockdowns, it has been hard to exercise, but to ski effectively you need to be strong and fit. If you need some help and advice about your injuries or equipment we’re here to help. I’m very interested in any feedback from experts in the ski industry about anything I’ve written above.

Happy skiing!

Written by:

Dr Victor Wilk (Musculoskeletal Medicine – MBBS Grad. Dip. Musculoskeletal Med. Masters Pain) in conjunction with Bruce Gilmore (Physiotherapist / Gym Rehabilitation – BPHTY (Physiotherapy))