Dario Cologna’s Quietly Dominant Season

Cologna won the World Cup overall, but I always feel like he’s sort of in the background compared to other top skiing personalities. Doing well in the World Cup overall rewards not just speed, but showing up at tons of races and skiing fast. For instance, let’s check out his won/loss record versus the next several skiers on the points list. First, distance and sprint combined:

This looks pretty dominant to me, with the exception of Petter Northug, who skipped a good portion of the season. That was partly intentional on his part, to prepare for the Vasa, but then he got sick and missed a bunch more racing. So Cologna certainly deserves the credit for actually showing up and performing, but I’d still probably put more money on Northug, head to head.

Of course, we can break this down into distance: Read more

Points In Europe vs North America

If you hang around skiing in North America long enough you will eventually hear people talking about point differences between races in Europe and North America (or the US in particular). One of the most common forms of this is the complaint that penalties (and hence points) are artificially high in the US, compared to Europe.

While I’m certainly sympathetic to criticisms of the vagaries of FIS points, I’ve always felt this complain was a bit short on data. It’s certainly plausible that race penalties are systematically lower in Europe, but that doesn’t necessarily mean that the differences are in some sense “wrong”.

The most direct way I know of to examine these sorts of issues is to isolate individual skiers who raced in North America and in Europe in a given season, and compare their points. If the North American races are seeing artificially high point levels, you would expect the average skier’s points to be systematically higher in North America than in Europe. (If FIS points worked perfectly, they’d be roughly the same.)

Doing this raises some sticky questions of which racers and which races to include. Since this is most often raised among North American non-World Cup level skiers, I think it’s most instructive to restrict ourselves to just that category of skier. So we’re only going to compare points from non-World Cup level events.

Here’s our first graph:

Each dot represents a single skier. Specifically, the difference between the median FIS points for North American races minus the median FIS points for European races. (Obviously, only skiers who competed on both continents are considered.) Clearly, this shows that there is a lot of variation from skier to skier, as we would expect. Someone might be killing in the US, travel to Europe and get sick and race very poorly, or vice-versa.

But it’s the blue trend lines that we’re really interested in here, since they are what will measure systematic trends. Given the scale of these plots, it’s a bit of a challenge to interpret. So let’s redraw just those four lines on a common scale:

Remember, the y-axis is North American points minus European points. If North American races systematically have higher points, we would expect these trend lines to be solidly above zero. And some of them are! Or at least, they have been in the past.

The line that stands out as the most different here is the men’s distance line. For a while it flirted with approaching zero in the mid-00’s, but has spent most of its time at around -20 FIS points. This means that US/CAN men, on average, get FIS points that are around 20 points lower in North American than in Europe. This is the exact opposite of what we’d expect if North American races had artificially high FIS points.

The other three lines have generally been above zero, sometimes by quite a lot, sometimes just barely. But all three have dropped dramatically over the last 3-4 seasons. This past season, the only one still above zero is women’s sprinting.

The other thing to note here is that FIS points for sprinting only captures qualification speed, nothing more. Any differences in competitiveness in the heats would not be captured here.

A Few End Of The Year Numbers

Just to follow up on a few tweets over the weekend…

Skiers from 10 different nations had podium results in men’s events, and only women from 7 different nations did the same.

The nations with the most podiums are in stark contrast. For both the men and women, you of course have Norway in the lead. They had 9 different men reach the podium 32 times, and 7 different women reach the podium 67 (!) times.

Behind Norway you have Switzerland (tied with Russia) each with 20 men’s podiums. But “the Swiss men’s team” is actually just Dario Cologna, one guy. Similarly, the second most women’s podiums went to Poland, i.e. Justyna Kowalczyk.

Interestingly, the numbers for biathlon are a bit different. There, 8 different nations had podium winners in men’s events, and 11 different nations for the women. Amazingly, none of the women’s teams had more than 2 different women with podium results. For the men, the Russians had 6, while the Germans and Norwegians each had 3. (Granted, I think the biathlon schedule has fewer starts in it, though I could be wrong.)

The season isn’t quite over, but across every FIS race I collected so far this season, Justyna Kowalczyk is leading with the most number of starts (including stage races) with 42. Of the ten with the most starts, 8 are women. The two men are Devon Kershaw and Alex Harvey. (Obviously, this is a silly statistic, because there are tons of races that are not FIS sanctioned. But we’re allowed to be silly every now and then.)

The largest FIS penalty this season was 211.20. (The largest I have recorded is 246.40). The largest FIS points earned this season was 2643.82.

Jessie Diggins and Young Talent

Earlier this week I tweeted a little nugget I stumbled across: that Jessie Diggins now owns around half of all top 30 results for US skiers 21 years old or younger over the past two decades. In contrast, the most any single Norwegian contributes over the same time period is around 10% of all their top 30 results by skiers 21 or younger.

That fact illustrates two things to me: (1) Jessie Diggins may be the best talent the US has seen since in a long, long time, and (2) the US is really quite bad at developing skiers at younger ages. Usually, our best skiers are well into their late twenties or even thirties.

Among young World Cup skiers, how does Diggins stack up? Well, of her 16 starts, she was in the points over half the time. This is well behind the likes of Krista Lahteenmaki, Maiken Caspersen Falla and Heidi Weng. But it was better than Finn Hagen Krogh, Gleb Retivyhk, Petr Sedov and Hanna Kolb.

This all got me wondering what the age breakdown has been more generally for top thirty finishers, so I made this following graph:

(The handful of bars that don’t reach all the way to 100% are due to a small number of skiers, mostly Russian, from the 90’s who I don’t have a year of birth for.) Not surprisingly, the under-21 crowd is more strongly represented among the top sprinters.

Quantifying Technique Speed Differences: Sprinting

Like last time, we’re looking to quantify somehow the average difference in speed (in sec/km) between classic and skating. Only this time we’re focusing in on sprints. Organizing the times for the heats is a bit of a challenge, so I’m only going to consider the qualification round. So essentially we’re just looking at speed differences over much shorter distances.

Following the same general procedure to fit a model for the sprint races, we get the following results:

Again, happily, freestyle is faster than classic. Note that I’m not really considering the course length for sprints, so I’m essentially assuming that the differences between a 1km race and a 1.8km race aren’t going to be too meaningful. Recall from last time that the men saw a difference of between 8-14%, the women between 5-12% with the longer races tending to see a smaller difference between skating and classic, on average.

What’s interesting is that in this case we get a difference of around 8.4% for the men and 9.0% for the women. Given the differences we saw in 5-10km races on Monday we might have expected larger differences.

What I think is going on is that the speed advantage of skating is sort of non-linear in race length. For very, very short distances there isn’t enough time for skating’s efficiencies to have an effect. But when the races get really long, the increased efficiency in skating starts to be counteracted by physiological issues that will be more constant between techniques. So there may be a sort of sweet spot in between where skating makes a huge difference, but less so at the extreme race differences.

The strongest case for this I could make would be to consider truly absurd extremes. You’re not likely to see much difference between skating and classic in a 5 meter race. However, you also probably won’t see much of a difference in a 500km race. In the former, skating’s advantages never really get the chance to take effect, and in the latter the relative efficiencies of the two techniques probably may pale in comparison to the pacing demands of a race that long.

Quantifying Differences In Average Speed Between Classic/Skating

I received an email recently from a reader who pointed out to me that Marit Bjørgen completed the 30k classic mass start in Oslo this season in 1:26:09.8, last year at World Championships Therese Johaug did the same course, mass start, skating in only 1:23:45.1, which is only a difference of about 2.8%. Surely, skating is more than 2.8% faster than classic?

Now, there are all sorts of reasons why unusual differences like this could occur. Strange weather and snow conditions, obviously, is the major culprit. My memory for those things isn’t so good, but my correspondent assured me that the classic conditions for Bjørgen were not favorable, which should have made the gap much larger, one would think. (I’m also assuming that the course really is identical, which is another factor that I have very limited knowledge of, being many thousands of miles away with limited TV coverage.)

As a first pass, let’s just look at the average speeds for the winner of all recent women’s 30k mass start races:

Now we can see that the average speed difference does appear to be quite large, but that my correspondent happened to stumble across a particular pair of races that weren’t that different. But clearly I can’t stop here.

Before going any further, let me be up front that there are numerous important variables that influence average skier speed that I can’t control for simply because I don’t have the data. Weather and snow conditions, as mentioned above, but also the fact that I collapse race distances down to their “advertised” distance. For instance, if the schedule says it’s a 15km course, that’s what I call it. The PDF race results will typically have a more accurate number, but pulling data out of PDFs is just more trouble than it’s worth.

With those caveats in mind, I went ahead a fit a big complicated model. Well, it’s not really that complicated, but I’ll spare you most of the details. Basically, it models average speed among the top 30 skiers as a function of gender, technique, race type (mass start vs interval start), race length and time (to account for changes in speed between, say the mid-90’s and now). There were a little over 16,000 observations in the data set used for this model.

Then we can look at the model’s estimates for the average speed of skiers in various types of races. First, the men: Read more

Race Snapshot: IBU World Cup Mass Start

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