My blog is about downhill skiing. My site is for beginners to learn quickly and safely and for intermediates to update their technique or teach a friend. It highlights AlanR Ski Method, a user friendly, safe, effective learning process for a beginner skier. Included are a video and manual. Included also are enhancements, observations, thoughts and tips, etc.
Sunday, 24 February 2019
How Skis Turn
Ski turning is a fundamental part of alpine skiing
sport. How well people ski is defined by how well they can make their skis turn in all conditions of snow
surface and terrain. So the questions how do skis turn and how do you make them
Ski design has evolved over many years with each year bringing in a new wrinkle to make skiing easier
or to explore a different form of skiing. This blog is about how all mountain
and recreational skis are designed to make skiing better.It is a engineers perspective trying to make
a very complex process easy to understand in common language. To this end, I will leave out all my coded technical
First, ski turning is a symbiotic relationship between
three main components, the skier, boots, and
skis. The boots and skis are chosen to
fit the skier so all can work together to make a turn.
The turn.The turn is made of 3 parts.The
first part is the transition or start of a turn.This is a dynamic process, moving forward in
a curve fashion.The perfect curve is an
arc of a circle that is split into 2 parts at the middle of the curve.It is not quite perfect since the arc is used to both change direction and
control your speed.Controlling speed is
the none perfect part.
The ski slides slightly sideways
through the arc roughing up the snow. A “carved” turn has the minimum amount of
roughing called side slipping and leave a very narrow snow path. On the other extreme
where both skis are in a snowplow or wedge shape maximum of roughing or side slipping occurs.
This latter form of skiing maximizes the amount of ski path width and side
slipping for a beginner. The ideal path of a turn has a uniform amount of side
slipping on both halves of the arc.
The ski.Here is where it gets a little tricky. Skis are made in many different
shapes and sizes for the many different uses.
All Mountain Ski
I will stick with the all mountain ski that can be used on both hard
packed and light powder snow. Newer skis are becoming wider under the foot and
little longer again.Basically, they are
narrow at the boot mounting in the middle and wider at the ends. This hourglass
shape makes skis unstable for moving in a straight line but helps to make
turning much easier (Figure 1). Also, skis usually have flexible ends that will
bend for a given load. The amount of flex will depend on what the ski is used for.I’m assuming the boot and skis fit the skier.
When a ski starts sliding it is like
turning on a switch, it becomes alive.As soon as it starts to move it gains kinetic energy with speed. The ski
must then be controlled.
To make a moving ski turn is a simple
You, the skier, must tilt your knee (figure 2) in the direction you want to go and at the same time press on the ball of your foot to move the
balance point forward (figure 3).
Ski Pivot Locations
This engages the front portion of the ski
tending to bend the ski (the darkened area on the ski in figure 1). The more
you press on your toe pad the more the ski will bend and turn on the forward
pivot point. This puts more pressure on the front of the ski and relieves some
pressure on the back. You can then control the size of the arc and the amount
of side slipping. Hence the shaded area showing the change in of the arc shape with the change in pressure, in the (figure 4). As the turn progresses the pressure on the
boot moves back to the heel and thus the pivot point.The transition starts again.
What is this kinetic energy that I
slipped in? Simply, it is the ability to do work. As soon as you start to move
you have it.You have to stop to get rid
of it.In skiing, you push snow out
around. This will either slow you down or if you push hard enough you’ll stop. You
can also use some of this energy to move your skis around by just pressing on
your skis at the right place and time. This is similar to riding a bicycle
where it takes very little energy to steer the bike. You use a small amount of energy,
in order to move a large heavy object, in a different direction.
The boot. I use a relatively soft forward flex
boot and like to keep my boots loose on hardpack snow. This allows my ankles to
bend but still have the side rigidity of the boot for making the ski’s metal
edge dig in. The boot has another function in that when clamped down in place
it will stiffen the centre portion of the ski. This function helps when skiing
on ice conditions. It also ads weight for kinetic energy.
The Person.How you stand on skis is most important in making
them turn easily and effectively. If you can shift the pressure on your boots
from toe to heel equally well, then you are centred on your ski. The easiest
way is to just move your boot forward and back under your upper body.Leaning and/or moving your hands back and
forth works. There are other ways to start a turn such as pushing on the middle
of the ski or on the boot heel. Pushing on the middle of the ski takes more effort
and time. Most people are taught to ski this way. Pressing on the heels moves the ski balance
point to behind the boot, also a way to ski. In the adaptive sports application
there are some people that can’t bend forward or get their weight forward, then
this is another option.
Remember this is about skis turning
not skiing.The person must add the
skills and timing to make turning happen.
Basically the ski is shaped and bent to follow a chosen path.