Ski Design for the Olympics
Most of us aren’t Olympic athletes. But if we were, we’d be very much interested in the design of our equipment.
Time and again we’ve seen athletes push the limits or experiment with diet, training, technique, rest, schedules, and, of course, equipment, trying to find that smallest edge that can bring them from a fourth-place finish to a bronze medal, or even reach the top of the podium.
And speaking of “edges,” a lot of sports at the Winter Olympic Games rely on edges for the athletes to propel, cut, spin, twirl, flip, fly, turn, and slide across the snow, ice, and sky to impress judges or beat the clock. From the blades of a bobsled to the contour of a snowboard, advances in technology and design differentiation is clearly on display at the games. In these sporting events, where the conditions and objectives are precisely defined, one doesn’t seek robust equipment that works in a variety of places. Rather, one seeks an optimized design tailored to the exact attributes, such as height and weight, of the athlete and the predicted forces from their individual technique.
The following three skiing events demonstrate this principle beautifully, albeit briefly, as each uses a different shape, size, and weight of ski.
The Nordic events, which include cross-country skiing, relays, and the biathlon, (where skiing is combined with shooting), require long-distance, ski endurance efforts. As any long-distance runner would know, carrying extra weight during a race is a disadvantage. That goes for both bodyweight and equipment weight. Ignoring the obvious bodyweight factor, the weight minimization preference factors into the design of Nordic skis which are always long, thin, and as light as possible. But at the same time, the skis need to withstand the forces of the athlete’s weight, and the dynamic forces of the ski-snow interface at the ski’s edge so that the Nordic skier can push off the snow and propel themselves forward. More edge could mean more contact with the snow and possibly more power. But that requires a longer ski, which usually means more weight and potentially more contact surface resulting in more friction as the ski slides along the track. Thus, the length and shape of Nordic skis find the optimal balance between weight, length, and strength, while trying to minimize friction. These skis are also often very straight with little to no curvature as the sport doesn’t require fast turning. There are, of course, turns and bends along the track, but those do not characterize a majority of the race and are usually at a lower speed, with lower angles of incline or decline. Therefore, the added ski curvature and width to help at those rare moments wouldn’t be worth the weight.
On the other hand, Alpine skiing, subdivided into various events, such as downhill, slalom, and super-G, can make use of shaped skis. In all of these events, turning as quickly as possible is crucial to minimize the distance between gates (the red and blue plastic markers), while maintaining a high speed in order to cross the finish line in the least amount of time. For most of a downhill race, the forward motion is caused by the force due to gravity, and not by pushing off the snow as it is in Nordic events. Likewise, since sharp turning is a key element in downhill skiing, the turn radius of a pair of skis is a crucial factor to consider. Generally, the shorter the ski the tighter it can turn. But with a shorter ski, there is less of an edge to use (after all, it’s shorter!). So, to increase the total amount of edge, curves on skis have been added to keep the overall ski length down, but increase the edge length since it’s now no longer a straight line. But there are trades with downhill skis as there were with cross-country skis. Heavier skis have more potential energy that can be converted to kinetic energy (so should downhill skiers be heavier?). But is the additional friction worth it with a heavier and likely longer ski? And what about stability? Smaller or shorter skis are better for turning with a smaller radius but are less stable, because of the lower surface area contact with the snow. If you don’t have control during the turn, it’s all for nothing, and the number of crashes and “Did Not Finishes”, will increase. These are trades that must be optimized for the exact snow conditions at the Olympics. Perhaps even more so, if the snow is man-made. It would be silly to use Nordic skis for Alpine Skiing and vice versa. People do that but they don’t have gold medals at home. In contrast, athletes with medals optimize their ski design for the event in which they competed.
Lastly, in many Alpine skiing events, the athletes might take small jumps as they weave through the gates and soar over a temporary drop-off, but nothing compared to the Ski Jump event where the focus is solely on the jump itself. Ski jumpers have big, long, heavy skis. These skis aren’t really used for turning (at all) and so are very straight. There isn’t friction with the snow during the jump (yes, there is some air friction or drag), but there can also be lift. Thus, what’s unique about these skis is that the larger surface area can give a little more distance because of the increased time aloft due to the lift. Of course, the athlete needs to know about the angle of attack and optimize the roll, pitch, and yaw angles of their lifting surface for stability, but that comes as they practice and learn to control the in-flight portion. (In fact, the ski jumper will try to get some lift from their body shape and angle too, but let’s just focus on the skis). One might think that a heavier ski is always better due to the potential to kinetic energy conversion while the athlete is accelerating down the incline, but again, friction needs to be balanced against that benefit. Still, skis are heavier, longer, and wider to help with the landing as well. The same force over a larger area reduces the pressure at impact, and that is clearly a more stable and safer strategy.
The three examples above are classic examples of optimal design. This occurs when the conditions and external environment is well known and one can spend a lot of effort continually improving the quality of a product to respond to those conditions. Each of these three sports has even more dimensions not discussed above with numerous details that come into play with the trades between size, shape, and weight. For example, the material used, the stiffness or flexibility, and even the weight distribution along the ski length are important factors. Athletes will trade these with other attributes, including their own style, physical characteristics, experience level, and coaching strategies.
The above descriptions barely scratch the surface of the multiple dimensions in optimizing skis for an Olympic sport. As you watch the athletes hold up their skis in front of the camera (a small price to pay for being sponsored by that particular ski design company) while waiting for the judges’ score, please appreciate the countless hours and optimization efforts that went into the design of that exact ski.
After all, almost any product has more dimensions and trades to consider once one dives down into the details of optimal design. If you want an exceptional design, be prepared to get into the trades, details, and minutia. But know that sometimes, minutia is what makes all the difference between a chunk of silver and a chunk of gold.
