… and matching equipment to skiers in general.

I bought a new pair of boots the other day in an end-of-season sale. The process was not without interest, and started me thinking about how the industry manages to sell us over-specified gear by applying the wrong parameters to our requirements.

First off, boots are usually categorized into beginner, intermediate, advanced, and expert (within separate ranges for men and women). Leaving aside peripheral features such as walk mode, cuff adjustment (wrongly called canting by most manufacturers), ramp angle adjustment etc, the main differentiator is the flex index. Typically, beginner / intermediate boots are < 80, advanced 80 to around 110, and expert 110 to 150 or more. And the higher the category, the higher the cost.

Now, as an instructor, I’d probably be classed as “expert”, so I need a stiff boot in the range 110 upwards, right?

Wrong.

I have it on good authority that flex is measured by a machine which applies a force to the cuff sufficient to distort it forwards by a standard number of centimetres relative to the shell (the final figure being an average over a large number of repetitions). Now the magnitude of the force is the rate of change of momentum (F = dp/dt = mdv/dt). So the force I can apply to the cuff is related to my mass (weight), and my velocity. The velocity here has two flavours – there is the velocity I can produce relative to the boot (ie due to my power), and there is the velocity at which I am skiing (relative to the ground – which comes into play the more sharply I turn and the more ruts I hit).

Let’s assume I’m around 10st in weight (not far wrong). The above analysis suggests I need a flex index around a third less than for someone who is 15st. Also, the slower I ski, the lower flex index I need. The correct flex is somewhere between not being able to move the cuff at all (too stiff) to moving the cuff so far that the 3rd buckle on a 4 buckle boot mashes into the top of the shell or the 2nd buckle (too soft). Within that range, it’s down to personal preference. So where a 15st racer might find a 130 flex right, I would probably be fine with a flex in the range 80 to 90 for what I want.

And what do I want in fact? Well, I need a softer flexing boot that’s comfortable enough to allow me to stand around all day when teaching and which allows me to demonstrate technically correct skiing at slow speeds. But something that’s stiff enough to support me at higher speeds and in the rough stuff. So I ended up with a flex 80 boot this time around. My old boots, veterans of 6 full seasons, were 90. So I ended up being classified as intermediate / advanced on the boot-fitting record (presumably in case I sue the shop for selling me a boot which is too soft for my ability level).

And if I wanted to race? Well, I’d probably have to buy a stiffer boot just for racing.

The moral of the story is to look at your physical characteristics and your skiing preferences, rather than buying the stiffest boot for your ability. If you get a boot that is too stiff, it will compromise your dynamic balance and your overall skiing performance.

What if you get a boot that’s too soft? Well, the news isn’t that bad. With modern skis, we are told to balance right in the middle of the boot, right in the middle of the ski. So you really don’t need all the support that a stiff boot gives you (but you do need some – see Toe, arch heel?). One of the favourite exercises on instructor courses is to ski with the top buckles of your boots undone, and the power strap loosened, just to show that you are balanced correctly on your skis. You can ski without any support from the boot! Try it, it can be quite educational.

And while we’re on the subject, don’t be tempted to buy the stiffest top-end racing skis unless you are both powerful (ie large mass), and ski at racing speeds. Yes they look cool, but they won’t do your general skiing any good at all.