The science of skiing v snowboarding

By J.P. | WISŁA

AS LUCK would have it, with vast swathes of the Northern hemisphere paralysed by snow, Babbage finds himself in the one place where such conditions are a boon: a ski resort. So, in lieu of our usual Difference Engine column (whose author is taking some well-deserved time off, possibly on the snowy slopes of California), he has decided to investigate whether science can help adjudicate a perennial feud between two warring factions of snow-sport enthusiasts. Which is superior, skiing or snowboarding?

As physical fundamentals go, there is little to tell the two disciplines apart. Both rely on converting the potential energy painstakingly accumulated by mounting a hill into kinetic energy on the downward zip. As a rigid flat surface (or two) slides over snow some of the energy is lost due to friction and released as heat (a bit is also lost due to drag generated as the rider's silhouette cuts through the air). That heat, combined with the pressure created by the sliding surface bearing down on the ground, melts the snow underneath it. This forms a thin film of water which lubricates the bottom of the surface, explaining the eye-popping speeds attained by devotees of both disciplines.

Whereas the formulae governing the downhill run are the same for the two sports, their respective biomechanics differ considerably. First, it is easier for the novice skier to keep his centre of mass tucked away safely between the skis, thus avoiding falls, even when turning. The snowboarder, meanwhile, has constantly to worry about his mass centre straying beyond the board's edge. This is especially tricky when trying to change direction. As a result, bruised bodies are par for the course before a neophyte gets to grips with the basic technique.

Moreover, the fact that snowboarders bear down on a single surface or edge with their full weight, whereas skiers divide the load, appears to translate into the latter's better performance figures. Crucially, skiers go faster. The current speed-skiing record stands at just over 250 kph (156 mph) against 200 kph or so for a snowboard. As a result, they jump higher: 10.7 metres (35 feet) against 9.8 metres in a quarterpipe (as a concave ramp used for such antics is known). They also fly farther. The longest recorded jump on alpine skis is 112 metres, compared to a paltry 56 metres on a snowboard. That is before considering the whopping 230 metres or more attained by professional ski jumpers on "the mother of all jumping hills" in Planica, Slovenia. But since they use specially designed equipment and venues, the comparison hardly seems fair.

Snowboard buffs appear to have the upper hand along just one, albeit crucial, biomechanical dimension: that of of high-velocity tumbles. When a snowboarder trips over while hurtling at speed, his frame is kept intact on a single plane by dint of both legs being locked in place on one board. Nasty falls are not, of course, unheard of. But they pale in comparison to spectacular skiing accidents. As all four of a skier's limbs can move independently, there is more scope for the body to be put out of joint (literally) when it all spins out of control. To this Babbage, the sight of a hapless skier performing inadvertent cartwheels down a slope, flailing skis and poles lodged repeatedly in the snow, evokes images of the grisly practice of execution by dismemberment, with gravity rather than horses providing the ripping force.

Croppers aside, skiers do win hands down in all other aspects of ergonomics. That is not so much because skis are somehow inherently better suited to the whole winter-resort infrastructure. Rather, it is the other way around. Ski resorts (as the name suggests) predate snowboarding by decades. They were created explicitly with skiing in mind and have changed precious little since the modern snowy getaways (ie, ones with ski lifts) began cropping up on a large scale in Alpine countries in the 1920s. Witness all the flat patches of piste which gradually bring riders to a halt (either before another downhill section or a ski-lift queue). A doddle for skiers, who can push off with poles or use the free-skate technique, they are a nightmare for snowboarders. The latter are forced to unclip the back foot and push off with it, in an attempt to imitate the propulsion method used in skateboarding (a meagre attempt, one might add, since a snowboarder's front foot remains bound to the board at 90 degrees to the one generating the forward movement). Alternatively, they can take off the board altogether and leg it. Either way, the upshot is dispiriting, and made worse by smug skiers whizzing by unfazed.

Snowboard-unfriendliness culminates in the surface lift (like a T-bar, say, or a rope tow). These pull the rider up the slope without lifting the board off the ground, as do chairlifts and other aerial contraptions. On skis, where the rider faces forward, he slaps the tow between his legs or behind the bum and lets himself be whisked up, balanced and composed. On a snowboard, the torso's natural position is more or less perpendicular to the direction of motion. As a result, the contortions required to latch onto the tow often end in disaster. As the rider's centre of gravity strays beyond the board's edge, he duly flips over, is dragged for a bit, before being forced to admit defeat and remove himself from the path of an encroaching—and invariably poised—skier. This often happens a fraction of the way up the slope necessitating a despondent slide to the bottom of the lift where the whole ungainly exercise begins anew. It is a sorry spectacle.

Snowboarders do hold one, if small, ergonomic advantage over skiers. Trundling around the slippery path to the restroom in inflexible, moulded ski boots is far from comfortable. Snowboarding footwear, on the other hand, is just a slightly stiffer and heavier version of ordinary boots. Not only is walking in them perfectly pleasant, but this Babbage has actually driven a manual-transmission car (with a clutch pedal) wearing a pair.

Ultimately, though, the deciding argument may come from an unlikely quarter: cultural anthropology. Skiing originated as a mode of transport on snow-clad flats at least as far back as 6,000 BC. The downhill variety emerged only in the late 19th century, almost as an afterthought. It was not for another few decades that it took off as a recreational activity. (The simple explanation is that in order to get down a slope one must first get up it, which was far from easy before the advent of the ski lift.)

Snowboarding, by contrast, was born not of a utilitarian desire to get around, but of unadulterated hedonism. It was conceived from the first to be fun. And all things considered, it seems the more natural way to get down a slope. In an outtake from "Lines", a documentary about big-mountain snowboarding in Alaska, Mike Renquet, a legend of the sport, offers the following thought experiment. Imagine a caveman asked to choose how to get down a snowy mountain. Would he strap on two separate wooden slats and lean forward? Or rather stand sideways on a broader plank and lean back a little? Mr Renquet does not think the theoretical troglodyte would plump for the skis. Nor does Babbage. But then again, both he and Mr Renquet may be biased.