Probably the most often asked gear question here at Epic is "What length of ski Xshould I buy?" I got somewhat intrigued by the constant repetiotion of the same arguments and I decided to look into the correlation of ski sizes and body parameters. I also noticed that in the past companies offered skis in 5-6 lengths, nowadays they tend to offer them in three sizes, essentially the equivalent of S,M, L sizing the clothing companies offer. My thought that those sizes roughly correspond to people sizes and the companies themselves adjust the length of those three sizes to compensate for the particular nature of the skis that they make. Unfortunately, unlike jackets, a misfitting ski is harder to spot, so it helps to look at the numbers. Thanks to many of you, I got some data points from a brief survey thread, so after an evening of looking up the lengths that those skis come in, I threw them down on a graph (points are slightly dithered to avoid overlap). Here is what it looks like (trendlines and areas drawn by me by eye):
A few preliminary conclusions:
1. There is a definite trend, and fairly significant clustering. As Philpug pointed to me, Salomon was onto something when they cam up with their PR sizing in the past.
2. The weight is a more important factor than height, so that should be a primary parameter for choosing the ski size.
3. There is a fair deal of confusion on the boundary between sizes L and M- seems that some people are too timid to buy into the larger size that their body type demands even though they fall very close to the trendline (surprisingly, there is no clear correlation with ability, at least as stated in the surveys), and some people listen to their ego more than to their body measurements. There is also evidence that older sizing by height is still prevalent (notice that all the red symbols that are spilled over to the MED size area are above the trend line. The two red dots near the SM area belong to someone who looks like a young racer, so he is definitely an outlier.
4.Indeed the ski size roughly correlates with the size of your ski jacket (Euro fit:-).
5. I would strongly support sizing based on this type of analysis. In fact, if your demo suggests that you need to buy a ski in a size that does not fit this chart, then you are probably looking for a wrong ski for your level of skiing/fitness. In other words, if you feel like you can only handle a ski that is a size down from what the chart suggests, then you are not strong enough for that ski and you may look into something softer and more forgiving. If you belong to the M group and feel like the M size ski is too floppy, you need to get a more aggressive/stiffer model rather than a longer ski.
6. I'd say it again, the defining parameter should be your weight, not your height.
Now, flame away :-)