Sunday, November 4, 2018

Analysis of Boot alignment cannot be done properly without movement understanding.

Determining how to evaluate and change bow-legged skiing!

Skiing October 30th, 2018
Looking at this photo you might think everything is progressing well? However, if you look further at different frames of the same turn it's amazing how everything changes. 

After you read the whole article come back and compare this photo below to the others in the Yellow jacket. This photo is from last season where my alignment was set to my satisfaction.



(below photo) If we look at this frame which is slightly before, higher in the arc, than the one above, you can begin to tell there is something amiss. The outside ski isn't rolling over onto the edge, the knee looks bowed out. My hip angle is out of proportion with my lower body angles.

(below) This is same turn or arc, but it isn't finished to my satisfaction yet, I'm already bailing out of the turn, too early. "Why?" Again, what is obvious is the knee angle and the space between the knees. Also from a movement standpoint, this release is forced and too early.


Now compare this photo, to the one above, whcih was taken only 2 days before. The skis are still arcing, angled and still in the arc, the finish is balanced.

Now let's look at the process of identifying alignment in a scientific and measurable way. The photo (above) with the Black Jacket is from 2 days before and with no boot changes. The turn is more rounded at the bottom and still arcing. 

What is happening here and why are there such differences between the angle and the quality of the arc?

Let's dig deeper. First, these photos demonstrate how alignment affects your skiing. I'll explain how and where these problems originate and how to evaluate them.

The only difference or changes from the Black jacket day to the yellow jacket day are the skis. I change clothes when doing these tests to make sure I don't confuse one day to the other. 

Without real in-depth investigation, most initial analysis can be misleading. At first look, you could easily think the boot angle is too strong, or the footbed is wrong, the cuff is too close to the leg, or the ski base bevel is too flat? So which is it? 

It's obvious I know what I want from my skiing and for the turn. This is demonstrated by the first photo at the top of the page. I made the corrections and adapted my body for something under my feet that wasn't right,. Every skier will make adaptive movements to try to correct wrong alignment. In most cases the skier doesn't know they are adapting because they are so used to do it. Therefore a complete evaluation must be done if reasonable angles and ski performance is to be acquired. If you compare the top of the turn and the bottom it is obvious something isn't right in this case. 

Some might say, "well you screwed up, you are too far back on your ski, you are not levering or tipping the ski over enough" and so on. Unfortunately while right in this analysis, it's not the cause.

There is nothing wrong with addressing what you might say is a bad turn. This is done by addressing the movement quality of the skier first. In this case, I can eliminate the movement issues because this isn't my normal skiing. I have the advantage of also knowing that this feels terrible and that it hurts my knee. So how does one narrow down the real issue and correct it?

We already eliminated the movement component. Now let's address the boot sole angle or boot canting angle. Indoors this is measured by aligning the knee center to the center of the boot sole at the toe lug of the boot. Since I know this is done and correct based on previous measurements and my boot sole angle wasn't changed; the problem is somewhere else. Sure if you only saw the photos in the yellow jacket it would be reasonable to assume that that boot sole angle was too strong because this type of leg angle is common for skiers with a bow-legged skiing stance.

Ok, now we have eliminated the boot sole canting as the major issue. We can move to the cuff angle or cuff position relative to the distance or gap on either side of the lower leg. Too strong or too much pressure from the cuff can keep the shin looking outside or bowed at the top of the arc. However, when the foot, ankle, and leg try to tip the ski, a strong cuff set up will immediately drive the knee under the body in the loaded phase of the arc. This isn't the case here. Too strong a boot cuff determination can be confusing because at the top of the arc (where the ski is relatively unloaded) it appears totally different from the bottom of the turn, where the ski should be bent. Going back to the angles in the black jacket; everything here is right, and no changes were made to the cuff so we can rule out the cuff as the problem. 

There is one more place in the chain of events that has an influence on alignment and that is the footbed. An over-strong or high arched, rigid footbed can make the knee look outside and bow-legged at the top of the arc. This type of footbed can also make the ski run out or go straight halfway through the arc. So it can't be ruled out, it needs to be investigated. Since I know I don't have a rigid, high arch footbed I can also eliminate that issue. So I've checked all the boxes except one, the ski tune. 

The lesson here is the interrelationship between the indoor measurements and skiing performance. If you don't have a complete protocol for all the areas of measurement and where alignment of the boot and foot can influence skiing, you will struggle setting up a skier properly. The boot sole, boot cuff, foot and ankle positions in the boot have to be measured and optimized consistent with perfect performance. The process needs to be consistent and measurable or you will be all over the map with your alignment results.
On the other side of the equation, the final test and confirmation have to include the on snow skiing tests determining skiing results as I have done here with the photos.

Now to what caused the problems for my left-footed turns. Well first you can't judge by one turn. This same problem has to show up on almost every turn in a run if you want to be certain about your evaluation. 

The conclusion

In this presentation I allowed the least obvious of the alignment influences to take hold so I could demonstrate that you can't leave out anything that might influence your skiing. This particular alignment challenge shown here boils down to skis and ski base preparation. 


How do I know? I know where all the boot angles stand from the indoor measurements. The only thing that changed between the two days was the skis. I know that the skis I used on the first day where everything was very close to being right for my skiing have a 3-degree base bevel. They have a mild side angle tune. The second day I was on a race slalom ski with a 1/2 degree base bevel with very sharp 3-degree edge angles. The solution, or change to make in this case is, flat file the base, take out some of the side edge sharpness and all will be right. 

In the end, you have to consider all the places where alignment can influence your skiing. This is what we do at Harb Ski Sytems, where we have established the protocols that work indoors and on snow. 


2 comments:

Erik said...

You typically ski with a 3 degree base bevel? Isn't that a lot? I thought that you and Diana generally recommended between a 0.5 and 0.75 base angle. Or am I confusing something?

Harald Harb said...

Yes, 3 degrees is too much, but it's a great way to test your ability to manage your movements. The ski I was on isn't one of my skis, it was a demo that had not been tuned since last season. How do you get the ski to hold with 3 degrees? You have to counteract your hips and reduce the tendency to drive the knee into the turn. It's not ideal on ice as everyone knows. However, my Dynastar race slalom comes in very flat. it hooks everywhere and keeps the angle building difficult to achieve. Typically I ski a .75 to 1 degree on hard snow. I hand tune the base bevel into my Dynastars until they feel right.