Gear Guide Ski Boots: Let’s Talk About Flex, Baby

July 11th, 2023
Former Olympian and World Cup downhill racer Jono Brauer knows how to flex his boots and for Jono the boots need to be stiff. Photo: Thredbo

Mountainwatch | Krista Sturday

Skis might be the most exciting piece of equipment a skier buys but boots are undoubtedly the most important. I was once told by a person far taller than me that the boot doesn’t make the skier, but it sure can break the skier. And they are right.

Choosing the right boot depends a lot more on your anatomy than people realise. And this all comes down to the flex. Boots should offer you somewhere between 70mm to 100mm of forward knee movement once the boot is engaged. So, picking boots by colour, or the features you read about in a gear guide, is unlikely to work for you.

One of the biggest boot issues seen in people presenting to on-mountain boot shops (where people are in immediate pain) is from being in a boot that is too soft and flexible. This can present with sore calves, burning balls (of the feet), not feeling in control of the ski, or even arch cramps. Put these people in a stiffer boot, and the problems go away.

Most skiers sit happily somewhere on the bell curve. We weigh between 50 and 100kg and most of the time we ski between 30 and 60 km/hr. Except for professionals (racers, instructors, ski patrollers) and seasoned ski bums of your flavour of choice, we all benefit from a relatively stiff ski boot. If it’s your first week ever on skis, you need a softer boot that will allow you to experience the correct ski position while skiing sedately on a beginner slope. Once you’re in control – back on the bell curve with the rest of us.

Ray Wills from Orthoski working with a customer to ensure she has the right boots with the correct flex. Photo: Charlie Brown

The boot can’t tell how technically gifted you are as a skier, but it does know how much you weigh and how fast you’re going. It doesn’t know that you ski like an out of control Muppet (Kermit the frog is my spiritual ski guide he’s present, is kind-hearted, and is totally committed) but it can tell how enthusiastic you are on your ski. I’ve got a husband who skis like Animal – yells a lot, hits anything in sight and wears a crazy look on his face – we don’t weigh the same and yet the number on our boot flex is the same (different boot brands measure flex differently).

Getting your technique right is a combination of getting you in the correct position on the ski and getting the right message to your skis. The first step towards either of these goals is infinitely improved by having a correctly set up pair of boots. Getting the flex of the boot right for you is essential in achieving this. After that, you’re left with no excuse but to get a lesson to pass on the correct message to your ski.

So, if boot brands measure flex differently and your anatomy is pivotal in selecting the right boot, how do you pick the right one? Find yourself a great boot fitter who works on-mountain and knows their anatomy. There’s no shortcut. Unless you can put up with burning balls.

For more information onhow to buy the correct boot for you, head to