A common and misunderstood topic of conversation among both guests and instructors, is whether to put your weight on the inside ski or the outside ski. I often hear percentages being thrown around with such precise amounts e.g. 90%/10% or 65% 35% etc. While this can be a good way of explaining a concept or feeling to our guests, are these types of percentage based tips an accurate way of explaining good pressure control in skiing?
To start with, when talking percentages, one can only really differentiate or recognise 100%/0% and 50%/50%, anything in between these figures is very difficult to regulate when skiing down a mountain. When it comes to accuracy of figures you have to imagine that the body is made of parts (legs, arms, torso and head) which make a percentage of the total weight of the body. Let’s say that just one leg on its own is 15% of the total body weight, this means just having both skis on the ground means you have at minimum 15% on both skis. This already rules out the possibility of 100%/0%. For this reason, the percentage ratio is kind of inaccurate. A skier is not really in balance until they have settled their Centre of Mass (COM) over/on an edged ski whether it be the inside or outside.
Let’s break this topic down into 2 types of skiing so as not to get confusing:
- Groomed Slow skiing (steered and carved turns)
- Groomed Fast skiing (pure carved turns)
Slow Skiing
When “slow skiing”, a competent skier can get away with almost anything as there are no major forces involved. We can all ski down the hill lifting either the inside or outside ski and through muscular effort stay upright. That said, I think we all agree that a skier must balance on the outside ski to turn efficiently. When performing a basic parallel turn I can tell you first hand that whether my inside ski is on or off the snow, I am balancing on my outside ski. I couldn’t for the life of me tell you an accurate pressure ratio between inside and outside ski. However, explaining to our guests that we need to put 100% of our weight on the outside ski is something that I think anyone can relate to and will most likely get a result.
Balancing over the outside ski (at slow speeds) is a major component of any turn, so much so that some organizations believe this is all that is involved to turn. Other organizations believe that weight on the inside ski is the way forward. While I mentioned above that we (as skiers) can do both at slow speeds, I think it’s less achievable for our guests to balance on the inside ski. A weighted inside ski leads to the breaking away of the outside ski, upper body rotation issues and edging problems (to name the main points). At the end of the day when making a turn slowly a skier must be in the correct stance, apply a twisting force to the ski (using only the legs), tip the ski on edge (for grip) and flex through the turn to help balance over the outside ski. Blending these movements can only result in the Basic Position or angulation that we all recognise as good skiing. Without the balancing over the outside ski, the twisting of the ski and grip become very difficult. Also, it is simply harder to balance on the outside of your foot than on the inside of your foot.
Fast Skiing
When it comes to “fast skiing” there are larger forces involved which means we have to understand the physics behind the turn to discuss inside or outside ski balance. Many people are focused on the movement we make to press or push on the outside ski, however when skiing fast, the power we excerpt is very small in comparison to the centripetal force created in a turn.
Simply put, to stay in balance with these forces, a skier must align their COM and their ski’s edge directly against the centripetal force pushing against the base of the ski. The physical strength involved to do anything else (and stay upright) would be too great. This makes any decision by the skier to pressure, press or push on one a particular ski rather insignificant (particularly in the part of the turn where the pressure is at its greatest).
So the question is: do we align our COM and inside ski’s edge opposing centripetal force, or our COM and the outside ski’s edge opposing centripetal force? We have to look at which leg is more capable of dealing with load when we are making a high speed turn.
As a skier moves inside a turn to gain edge angle, the skier’s inside leg must relax or collapse to allow the hips to continue moving inside the turn. This shorter inside leg does not have the strength to deal with these forces. Pressing or balancing on this short inside leg (particularly where force is at its greatest) would be extremely dangerous on the knee particularly if the skiers hits a bump or icy section. This only leaves the outside ski as a possibility.
As a skier moves in, the inside leg shortens (as mentioned above), while this happens the outside leg stays long. This outside leg is in a much better position to deal with the pressure that is produced through the turn. While muscular effort is still required, the skeletal system can start to help take some of the load. For these reasons one must align their COM and outside leg against centripetal force.
We must now talk about different parts of the turn as the above mentioned alignment is particularly crucial where the pressure is at its greatest (in, and just after the fall line).
Transition: through the transition there is not a great deal of centripetal force and weighting a particular ski will depend on the type of transition the skier is performing. A crossover will demand pressing on the uphill or new outside ski. A crossunder will require more evenly weighted skis or pressure on the downhill or new inside ski.
Initiation: Through this section of the turn, the skier’s primary goal is to move inside the turn to gain edge angle. The centripetal force is beginning to build up but can still be managed by the skier’s movements. It is this part of the turn that inside/outside ski pressure is situational.
If a skier is skiing on ice then balance needs to be primarily on the outside ski. When the conditions are good, a skier can play around with weighting the inside ski to aid with inclination and COM movement to the inside. The initiation will also be affected by the transition type.
Middle: Now we are starting to get to the point in the turn where the centripetal pressure is great. It is this part of the turn (regardless of inside/outside ski weight during the initiation) where the skier must align their COM over the outside ski as mentioned above to deal with this force.
Completion: This part of the turn the pressure is at its greatest. Not only are we dealing with centripetal force but also gravity. Just like the middle of the turn, it is crucial that the skier be on the outside ski to deal with the force.
To summarize this article, when skiing slowly, a skier must actively balance over the outside ski to stay in balance and perform the other skills affectively. When skiing quickly, a skier must align their COM with their outside ski against centripetal force - but only when the centripetal force is strong. At other times a skier can weight the inside ski to help inclination or transition. Playing around with this inside ski weight at the right time may just take your skiing to the next level.