MIKAELA SHIFFRIN AND THE SIDECUT FACTOR


A follower reminded me today that at the end of my post THE MECHANICS OF BALANCE ON THE OUTSIDE SKI (February 18, 2017), I said I was going to explain the 2 steps to balancing on the outside ski of a turn. I got sidetracked for the two reasons below. This post is an essential lead-in to the discussion of the 2-step balance process.

  1. The dynamics of my blog has shifted significantly since I re-categorized my posts. Where possible, I try to tailor my material to the interests of my followers as indicated by blog stats. Stats show me a hierarchy of the countries reading my blog posts and the posts of interest from the most read to the least read on a given day. As an example, the top post today is THE SIDECUT FACTOR.  This just happens to provide an ideal segue to a discussion of Mikaela Shiffrin and her use of the 2 step process of balance on the outside ski.
  2. Understanding and embracing a new paradigm requires a shift in perspective especially when it is commonly believed that an issue was explained and put to bed ages ago.

In his book, Ulimate Skiing, LeMaster says:

All skiers learn early on the importance of edging skills. Ask them how they edge their skis, they crank their knees in (to the hill).

After the higher, all-plastic ski boots took over from low-cut leather boots, I distinctly recall ski pros demonstrating how easy stiff plastic boots made holding an edge by driving one of their skis on edge with their knee or holding a ski on edge with one of their knees as they moved over the snow to demonstrate how sidecut made a ski turn all by itself. Voila, knee angulation was invented as a universal explanation for all edge hold.

If a ski pro or coach saw an elite skier hold an edge on ice, they assumed they were using knee angulation. If the alignment of the outside leg appeared more linear (less knee displacement) than lesser skiers, it was explained away as unique to that skier. Knee angulation was knee angulation. Edging and balance? Easy. It was all done with the knees. Except it wasn’t what elite skiers were doing and still isn’t.

Since Shiffrin’s dominance at St Moritz, I have spent considerable time studying video of the races. Properly analyzing what is happening in terms of mechanics and biomechanics requires good quality video. While the quality of race video isn’t excellent, is better than most.

Let’s start by studying a screen shot of Shiffrin about to enter the bottom of a high load, red gate (left) GS turn.

shiffrin-red-gate

The first thing to note is the angle of her outside ski with the plane of the surface of the snow. I am estimating the angle to be between 75 and 80 degrees. The low minimal spray pattern off the ski from the forebody back indicates that the edge is engaged and following the path of the shovel with no chattering. The shovel is locked and higher relative to the portion of the ski under foot. It is powering Shiffrin’s line. Shiffrin maintains this high edge angle into the bottom of the turn, below the gate, without the ski slipping. In some turns, Worely holds even higher edge angles than Shiffrin.

The spray pattern on Shiffrin’s inside ski is radiating from about the binding toe piece back. The spray pattern suggests that the portion of the ski underfoot, while controlled, is displacing towards the outside ski.

How is Shiffrin able to establish and hold such a high edge angle especially with such a linear alignment of her knee with the line of her outside leg?

Some would immediately claim knee angulation explains the ability to hold such a high edge angle. Others would cite LeMaster’s 90 degree Platform Angle which posits that a ski sitting flat in a notch cut into the snow will not slip. I agree. That is why curves are banked on highways and race tracks. At high speeds, race cars will stay on steeply banked walls. But it they try to run with on set wheels on the top edge, they will exit the wall. Except Platform Angle explanation won’t work because the piste is so hard that even the sharp edges of Shiffrin’s outside ski are barely penetrating the surface of the snow. So there can no be no platform angle under the whole ski.

In order to understand how Shiffrin and Worely are dominating ladies WC GS and SL, we need to start by looking critically at ski sidecut, especially what happens when a ski is running on the entire portion of the edge in contact with the snow. Start by reading THE SIDECUT FACTOR. After I expand on sidecut in my next post, it should become obvious why the first step in the balance process is essential to the second step and how the second step enables racers like Shiffrin to carve clean turns at extreme edge angles.

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