|
|
Did you come here from a link on another website? See page bottom for latest version of this page.
"The story goes that an Olympian world-champion ski racer was out skiing with
his son. Son had on a pair of kid's skis with Mickey Mouse graphics, and Son was
horsing the skis around the turns with lots of body movements and arm swinging.
Dad said, "Now, Son, let Mickey do the work!" It is said that at the
end of a ski day, your skis should be tired from working, not you. In the snow/skis/skier system, note that "skis" come between"snow" and "skier". Once on a given area of snow, the skier can't do a lot about its character, and the skier is pretty much stuck to the skis by the boots and bindings used at the time. So if the skier is to influence what is to happen, it has to be by somehow positioning the skis so they will interact with the snow and make the skier go this way or that, and faster or slower. We all know generally what skis look like, but take a close look. "What is the most important part of the ski?" is a question sometimes asked in ski instructors' exams when they try out for certification. That is a loaded question. Anyone who has broken a ski tip (or feared to) while out in the woods will say the upturned end, or shovel, is the most important, for it allows the ski to run up over obstacles instead of diving into them. Skiers may not notice some other features. When skis are placed on a flat surface, like a solid floor, most skis arch upward in the middle, their
bases touching the floor only near tip and tail. This arch is called camber, or base camber. Why are they made this way? When you stand on the
middle of the ski, you flatten it to the floor and your weight is then evenly
distributed along the ski's length instead of just mainly under your foot as would
otherwise have happened. (It's the same principles engineers apply when they pre-stress
bridge spans or heavy-load truck beds; these arch upward, too, until loads flatten them.)
Note the lengthwise bend of the tipped skis, especially the skis on the outside of the turn.
Skiers also may know that the sides, or edges, of the skis are crucial. A ski that's base is flat on a snow slope will slide where gravity pulls it, directly down the slope When a ski is tipped on its side, however, its edges indent the snow, keeping the ski from sliding directly downhill--and if we are on it perhaps getting us to slide where we want. The edges are even lined with more-or-less squared-off steel to help the skis bite into the snow better.
Some advanced skiers might not notice another ski characteristic, one expert skiers should know about . Look down on a ski's top surface from above. Notice the ski is narrower under the foot area than at its tip or tail. This is sidecut or side camber. Why is the ski made like this? Setting the ski on the floor again, bottom down, first lift up one side of the ski. This will put the ski at an angle to the floor. Now, keeping the ski angled to the floor, and ensuring the tip and tail don't slide on the floor, press downward on the ski's middle, causing the ski to bend until the lower side of the ski touches the floor. If you followed these directions, and your ski is normal, the ski's line of contact on the floor will be an arc. The more you tilt the ski to a higher angle with the floor, the more of an arc you will get when you press the middle down again. Now do the same thing but on a rug. While still holding the ski so the arced edge presses against the floor, push the ski forward and watch the ski track along its edge in an arc. This shows how a tilted ski can turn us more or less depending on its tilt and therefore how much it can bend into an arc. (Be careful not to cut the rug!) If your rug has a bit of depth, it will be like snow in that the higher the ski is tilted, the more of its weight is put on a smaller area, increasing pressure on the edge of the ski and causing it to bite into the rug--or snow--more deeply. What about ski dimensions? Why are they long and wide? And how long and wide
should they be? Simply, a long ski tends to run straighter whereas a shorter ski
can be turned more quickly. A wider ski will hold you up so you sink less deeply
in
soft snow. The trick is getting the length and width that optimizes the effects
you want for given situations. In the recent past there was a trend to use wider skis. A good discussion
of why this has developed is posted on a website operated by the Ski Monster, as
But now for an
alternate view:
Depending on the
snow one is on or
in, one may or may
not need extra
flotation from a
wide ski. On groomed
snow it will take a
little longer to
move a wider ski from
one edge to the
other and even
though materials
have improved to
provide better
torsional stiffness,
a less-wide ski will
still have greater torsional stiffness
than a wider one. So
decide on your own
what you would like
and consider a
narrower ski for
most groomed- or
packed-snow And has this wide-ski craze been partly a fad? Read this from Ski for September 2015, page 46 "The Rise and Fall of the Fatties": "There's mounting evidence that superfat powder pigs have had their day...'There are still a lot of fat skis sitting on retailers' walls from two and three years ago', says Fischer's Matt Berkowitz. Skis with 80- to 90-mm waits remain the hottest sellers, and the fastest-growing segment is 101-110 mm." Another view indicates fat skis may put undue stress on knees as compared to narrower skis. See "Your Fat Skis Are Killing Your Knees: exits" for a report. Illustration from Unofficial Network. HOW YOUR BALANCE MAKES SKIS WORK. While learning "How Skis Work", we kept the skis on a flat floor. That's not where we use skis, however. We use them on hillsides. To make the skis work the way they are designed to, then, we must at times position our bodies to produce the same forces as in the flat-floor example. Our forces must be centered on the skis and perpendicular to them, no matter how the skis may slope or tilt. Imagine the gyrations we must do in our bodies to always have our main line of force perpendicular to our skis--especially when the skis are tilted. If the skis are flat to the snow and going down a steep slope, for instance, our bodies must be tilted forward from vertical. If the skis are tilted to the side, our lower legs must also tilt to the side, and somehow we must keep from falling over. To assume such positions is not possible while standing still in normal gravity mode. Only while we are moving and new forces of motion come into play can we manage to place ourselves in seemingly gravity-defying postures. Perhaps this is a little like a car going around a curve at high speed; the road-builders often bank up the roadway on one side so the car tilts inward from vertical but stays more nearly perpendicular to the road surface, and is less likely to fly off the curve's outside. And so when we speak of balance in skiing, we are not talking of the more usual balance against just gravity, but a much more complex and dynamic type. Learning these new balance positions and experimenting with them constitutes both the joy and the frustrations of learning to ski. For those who enjoy motion, the journey is always fun. For some, however, who do not overcome a distaste, or even fear, of sliding, the journey will be more limited. One beginning skier confided to her instructor, "It's the sliding part I don't like." There is a lot of humor in her utterance, yet most skiers in spite of their efforts to overcome, at some point will find that it's fear of "the sliding part" that ultimately limits their advance in skiing. That skier inadvertently gave the name of this skiing web manual. SHOULD WE EVER BE OUT OF BALANCE? "No!" says conventional wisdom. But consider how we learn to walk: moving a foot forward does not get us to walk; we have to also tip forward as the foot is moved forward, starting to fall while at the same time swinging the leg so the foot gets under where the weight is going, thus moving a support forward so we don't fall. With practice we got so good at this most have forgotten how this works but we can watch toddlers to remind us how we walk. At first, beginning walkers may swing a foot and its leg forward without first tipping their tops forward, causing them to fall backwards. Watch runners: their upper bodies are ahead of their lower bodies and they are tilted forward, with their legs rapidly moving ahead from behind--especially true as they accelerate, less so when they are at speed. On skis, therefore, if we simply remain balanced against all the forces upon us--gravity, deflection of skis against snow, and perhaps wind--our skis will keep doing what they have been and so will we keep doing what we have been. To change our direction or speed, we must rearrange the forces on our skis by changing the rotary force we apply to the skis and/or how we tilt or pressure them. We make these changes ourselves. If we do not make the changes, the ski will respond to whatever other forces, tilts, and pressures occur anyway and we may be surprised at results. As our skill to do this rearranging increases, so also does our ability to manage ourselves on various ski slopes and snow textures. And consider this advice from Dave McCoy, founder of Mammoth Mountain Ski Area in California, a race coach, and father of several Olympians. He is telling how he coached Jean Saubert (at the time a would-be Olympian and later an Olympian): "...we taught her how to ski on all parts of the ski...forward for better control, better cutting and braking...and on her centers for extra balance and precision on rapid turns...on the backs to accelerate, shoot the skis out of turns and away from the gate, yet still catch her balance..."--Skiing Heritage, July-August 2015, page 26. [Editor--Jean Saubert raced on different skis than the ones we use today, but we can still get similar effect from modern skis by repositioning our balance proactively. We do this by repositioning our weight, levering against the skis in our stiff ski boots by using our muscles in the feet, legs, and core or even moving a hand(s) and/or arm(s) and/or head forward or back or to the side. Your editor once skied in a race camp with Jean when she was returning to her sport and even beat her-but only after she had been out of the sport for years.] The wise skier said, "In skiing, there are things (positions, movements, pressures) that we create and things that we allow; we should not create those things we could and should allow."  "SKIING
IS A SLIDING SPORT"--a skiing web manual: Skiing
Web
Manual Contents
Why Read
This Skiing Web Manual
That First Skiing Lesson
A Little Skiing History
Motion in Skiing
Conventional Skiing Wisdoms
Skier Excuses
Fear in
Skiing
Conditioning for Skiing
Equipment and Technique
Skiing Equipment
HOW
SKIS WORK
How
to Develop Balance on Skis
A Skiing Turn Simplified
The Final Skiing Skill:
pressure management
Tactics for Terrains and Snow
Textures and Racing
Skiing Tips and Tales--a potpourri
Exercises for Developing Skiing Skills
Children and Skiing
Age and Skiing
Gender & Skiing
Culture & Skiing
Skiing Ethics and Slope Survival
Slope Safety
Skiing
Environment Videos and Apps Glossary
Acknowledgements
SkiMyBest Website Contents
This "How Skis Work" page last modified April 11, 2024. Did you come here from a link on another website? For latest version of this page, copy to your browser: http://www.SkiMyBest.com/skihowsk.htm. Copyright © 2016, 2017. William R Jones. |
|
For a fun demonstration of how and why this works, see the one-minute video
