The Heli-Ski Blog

An Expert's Perspective on How to Fit a Ski Boot

Posted by Topher Donahue on Dec 20, 2011 8:20:00 AM

Buying ski boots seems like it should be easy, but for some reason when I start trying to decide which boots are the perfect fit, I always feel like Cinderella’s sister.

So for an expert’s opinion on how to fit ski boots, I tracked down Matt Carlson of Surefoot, the ski boot company that customizes Lange ski boots for the ideal fit and performance - a favourite brand among CMH Heli-Skiing guides.  Matt is a veteran moguls and aerials competitor who moved from the East Coast to Utah when he’d had enough of skiing on hard snow. 

custom ski boots heli skiing

He replied with what is certainly the best explanation I’ve ever heard on how to fit ski boots:

Generally, each level of skier ability requires a similar fit.  The goal should be to have a boot that is as snug as possible without being painful. Non-custom boots pack out very quickly, and will become much looser after just a few days of skiing.  Therefore, they need to be very snug at first.

Even though each level of skier needs a snug fit, there are a few different things each needs:

Beginner skiers needs a soft flexing ski boot.  Beginners do not have the balance of an expert, so the flex helps them stay centered in the middle of the ski.  A boot that is too stiff will result in the skier leaning back.  But there is a catch; often the softest boots are very poorly designed and are very wide.  Find a soft flexing boot that is not too wide, and not made out of poor quality plastic.  Typically the softest-flexing quality boot for men is about a 90 flex and for women is 75 to 80.

Intermediate skiers require a slightly stiffer boot to transfer energy quickly from the boot to the ski, but still soft enough to allow them some forward flex. Often the flex for guys will be 100 to 110 and women 80 to 90. The weight and height of this skier also helps to determine the flex.  The more leverage the skier has, the stiffer the boot the needs to be.  It is also more important for this skier to have a slightly narrower boot to transfer the energy quicker.

Advanced skiers have good balance and rely on their ability in order to stay centered over the skis.  Therefore, they can have a stiffer boot that will transfer the energy much faster and result in better performance.  This skier usually wants a narrower boot to transfer the energy faster.  Depending on the ability level, this guy will want a 110 to 140 flex and women 90 to 110.

For everyone: Ski boot companies save money by not making a 22-sized shell but just slide the 22 liner into the 23. If the shell is not the size of the liner, don’t buy the boot.  Most importantly the skier must not rent.  Rental boots are lowest quality of all ski boots and they do not help the skier improve or enjoy their hard earned vacation - plus they can be gross.

Custom orthotics:
If the customer is not getting a completely custom ski boot it is very important that they get a ski orthotic.

  • First of all, it must be specifically designed for skiing.  It will support the foot in the best position for skiing and result in more comfort and performance.
  • Ask the store what position they make the orthotic in.  All feet are different and one way of making the orthotic does not work for all.  Generally orthotics are made un-weighted, semi-weighted, or fully weighted.  If the store only makes them using one method, the skier should go somewhere else.
  • Find out if the ski orthotic will hold the foot in neutral - the best and strongest position for skiing.  If it does not hold the foot in neutral then they should not buy the insole.

Since all feet are different, the best ski boot is a custom ski boot.  But if that is not possible, then the skier must make sure the store has ski boots in several different widths.  Some examples are 98mm widths, 100mm widths, and 102mm widths.  If the ski shop does not have all these widths in various flexes than the skier should go somewhere else. The shop should also be taking very detailed measurements of the width and length of the feet to immediately narrow down the choices.

Ski racing –There are narrow and stiff boots available, but for children the flex still needs to be very soft.

Extreme cold – Some after-market liners like Intuition are great in the extreme cold, but they break down quicker and do not ski as well as other custom liners. Also find out what ski boot heaters are available.  The highest end boot heaters work very well - you get what you pay for.

Heat-molding a standard liner will improve the fit, but if heated the liner will break down faster.  Unless the liner is designed to be heat molded, it is usually best to just ski on it and it will mold to the foot the same amount heat molding will, but last longer.

The best is a custom ski boot with ski orthotic that holds the foot in neutral, a shell that is the proper stiffness and width, and a custom liner that fills in all the gaps between the foot and the shell.  A boot heater is always a nice way to top it off.

Of course the Surefoot Custom Boot is the ultimate for performance and comfort for everything from riding the lift at your local hill to a dream trip to the world's greatest skiing.

Photo of finding out if the boots fit in CMH Cariboos by Topher Donahue.


Topics: Product Information, Skiing, Gear, CMH Experts, Tricks of the Trade