The Measure of Classic Skis

Skis glide over the snow. Nothing prepares you for the wonder of it. The surprise, the jolt, the sudden slip, the return of that feeling that made you whoop and scream when you were little and still makes you curl up with pleasure. Surely those cave paintings from the Finnmark are a 4000 year old memorial to that feeling. Ancient man on skis sliding over snow grinning with delight.
We are more sophisticated now in the new millennium. I can
explain the mechanics of dry friction, of melt water lubrication and so forth -- but gliding is different from many physical phenomenon. Never do we come as close to being divorced from gravity as when we slide over snow or ice. Flying in an airplane is a complicated physical act but it is bland compared to sliding over snow.
So skis glide -- it is what they do, it is their nature. If they don’t glide, they aren’t skis. Cross country skis climb to the tops of hills and then they glide down. So they are a special, self sufficient kind of ski. Up and down big hills, little hills, across the flats. A human powered device for traveling over snow. Surely a marvelous invention -- on a
par with the wheel. Probably way ahead of it in deep snow.
Stone age man invented it and the concept remains the same. Functionally the same but with 4000 years of fine tuning. Improvements that inch closer and closer to frictionless flight
over snow.

Let’s take a look at today’s classic skis -- the grip and glide tools of snow. The ideal ski would glide friction free when it was supposed
to glide and would grip with perfect traction when it was asked. No overlap of functions. Grip and glide. We’re getting closer but still
a ways to go.

The Ski Research Group tests skis on-snow and in the lab (to see how we’re doing). And for over twenty years, those tests have documented steady improvements in grip and glide. Some of these improvements are technical -- better skis, better wax, improved trails -- but some are due to improved knowledge and understanding. Better data and better theory lead to a better (more efficient) match between skier and ski. In other words, “Skis that fit!

Friction is the friend and the foe of classic skiers. We need the traction of high friction from the kick wax to push against during the kick phase. And we need the slipperiness of low friction during the glide phase. Both of those conditions are dependent upon the distribution of pressure during the kick and glide phases.
To evaluate classic skis we measure that distribution of pressure and put numbers on the important factors. For grip the number is
called the Grip Factor (what else!) and for glide it is called Drag. Both numbers are measures of the pressure on the wax pocket.
The improvement in classic ski design now allows for selecting skis with a drag of 4 or 5 lbs. and a grip of well over .70. On page six,
we show pressure distributions for such skis. They are generally well matched and exhibit glide characteristics which approach
skating ski slipperiness.

To achieve such performance, it is not enough to just squeeze the skis together and measure flex and wax pocket. The pressure on
that wax pocket must be taken into account. To see how misleading flex alone can be look at the table on page three. A good example, 120.8 flex -- Magic ski (.74 grip/.00 drag) and right above it on the list, a ski with softer flex (117.5) but poor to inadequate grip. So, if you trust flex -- BEWARE!
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