Wikipedia:Reference desk/Archives/Miscellaneous/2019 January 13

= January 13 =

Skis
Why are skis so long? Wouldn’t shorter ones provide more agility? Temerarius (talk) 15:47, 13 January 2019 (UTC)
 * The dimensions of skis vary depending on specific intended use. Read Ski for more info. ←Baseball Bugs What's up, Doc? carrots→ 18:10, 13 January 2019 (UTC)


 * Ski length varies a lot, depending on the use, the size of the skier (height and weight) and fashions of the time. Skis also vary by shape (they're not just parallel-sided planks), width and stiffness (in several axes). 'Agility' isn't really the goal, or at least the right term for it. For one thing, skiers are often travelling fast (or want to) and aren't turning especially sharply (at speed, most turns will be large radius, long and sweeping). A skier wants their skis to do everything for them: to be agile, but also to be fast, to be stable at high speed, and to be appropriate for their style of skiing and the terrain. Most of all though, they have to be able to control them: long skis need different techniques, and you have to have enough technique (and be in conditions where that technique is appropriate) to ski on long skis. A good skier can ski long or short skis, in most conditions; a beginner will be on shorter skis, and is limited in what they can cope with. Skill level is probably the biggest factor in choosing ski length. Ski stiffness also matters - I've had skis (a sadly missed pair of Scottish-made Vielhabers) which were long (207cm, and I'm a shortarse), yet skied like a pair 20-30 cm shorter for their suppleness and control, yet flew like their long GS size - multiple internal torsion boxes (a Victorian idea, see tubular bridge) and lots of clever tech gave a pair which bent in all the right directions, without being floppy.
 * Beginners start with short skis. Largely because beginner technique starts with the "snowplough" and similar manoeuvres, where the ski is tilted and pushes around great banks of loose snow. This is hard work! You have to be physically both strong and fit to do so (skiing badly is harder work on the muscles than skiing well - although skiing fast turns tendons and ligaments to beef jerky). A shorter ski is just easier to shove sideways through a bank of snow.  Many instructors teach on a shorter ski than they would choose to ski for themselves, just because it's less work to demonstrate these early techniques  (and they weren't planning on skiing fast).
 * In the 1970s in France (and in one famous UK book), there was also a fashion for a deliberate short-ski learning technique known as 'Ski evolutif'. This put beginners on very short skis (and a gentle slope, or else they died) and taught 'advanced' techniques (e.g. carved turns) from the outset. Learners would change skis each day, going progressively longer as they improved.  There was even (early 1980s) a brand of ski called the 'Scorpion' which was of similar length, but with the bindings mounted near the rear (you ski through your toes and the front of the ski - the back end is largely decorative), had the sides cut to be convex and were 'extremely agile'. Mind you, they were totally unstable at any sort of speed, so it wasn't a fad that lasted.
 * The parabolic ski appeared in the '90s and was extremely concave at the sidecut. Also pretty short. This were hugely popular in the US, especially with people who couldn't ski, and they were rather limited in their ability to handle poor snow conditions, especially traversing on steep sheet ice. No-one has yet managed to make it down a Scottish hillside on a pair, owing to their inability to ski over either rock or heather (they handle OK on mud).
 * Freestyle skiing is probably the home of the short ski. Top-notch skiers ski a slope that's made of lumps and bumps, with the emphasis on agility rather than speed. Success is about demonstrating precise control, not racing the clock. Some aspects of this are timed, but even then, success comes from control, not just well-streamlined cojones.
 * When skiing gets faster, from slalom to giant slalom to downhill to jumping and flying kilometre, the skis get longer, wider, stiffer and more damped. This is partly to make them go faster, partly to be more stable when at those speeds. No-one can ski (or at least out-turn a supertanker) on skis that size for a 'typical' alpine skiing piste.
 * There's also Nordic skiing and, if anyone still does it, Telemark skiing. These use a binding where only the toe is fastened down and the heel is allowed to rise. This allows you to put your skis in positions not possible with Alpine bindings, giving techniques which allow useful turns on extra-long skis without needing the thighs of Hercules. Although again, there's a trade-off for stability at speed.
 * So, modern kit for beginners and once-a-year skiers is short and bendy, and will turn on a sixpence. But you won't go so fast, and if you did, you'd fall over. Nor can the modern short and deeply sidecut skies grip well on hard ice. Now I need to go and pour gin in my knees and dream of past glories. Andy Dingley (talk) 18:13, 13 January 2019 (UTC)