Drafting in Cross-Country Skiing Demystified

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Fabian Stocek, January 7 2025

In competitive skiing, strategy can often determine the outcome of a race, particularly in a mass start. We draw on extensive research from cycling, running, and skiing to highlight how drafting helps you to win or lose a ski race.

There are three main takeaways from this article:

  1. The faster you go the more drafting matters.
  2. The best place to ski in a line of skiers is 3rd.
  3. You can still benefit from drafting even if you're not directly behind someone.

Let’s now explain each of these points in detail.

The faster you go the more drafting matters

When you double your speed, air resistance increases by approximately a factor of four. Investigating the drag force formula, we can notice that the influence of the wind in the equation is squared, which is why aerodynamics matter so much more in cycling than in running. It's also why you benefit the most from drafting at higher speeds in skiing. A good example to illustrate this is the amount of power (in watts) required to maintain the same speed while cycling on a flat surface without extra wind.

The amount of power in watts a biker needs to exert to overcome the power from the headwind.
The amount of power in watts a biker needs to exert to overcome the power from the headwind. Fitted with a quadratic function. Data from: https://www.gribble.org/cycling/power_v_speed.html

The best place to ski in a line of skiers is 3rd

The optimal position in a line of skiers is third, where wind drag is significantly reduced. This advantage decreases only slightly in subsequent positions, but the ability to respond to attacks in a peloton also diminishes the further back you are. Skiers positioned farther back are also more likely to experience the "accordion effect" more acutely on undulating terrain, leading to significant variability in acceleration and deceleration as well as likelihood of an accident, which consumes considerable metabolic power.

Again, we can draw parallels from cycling: wind tunnel research shows that the power saved decreases significantly from the second to the third position, with only marginal gains beyond that. This research, however, mainly covers cyclists riding in line. In larger groups, substantial gains are possible toward the back of the peloton, where up to 90% of power can be saved compared to a solo rider at speeds around 50 km/h. In skiing, a benefit from a peloton typically occur only in large mass starts, such as many Ski Classics races or Worldloppet races.

Aerodynamic impact of cycling postures on drafting in single paceline configurations.
Data taken from Table 3 in: van Druenen, T., & Blocken, B. (2023). Aerodynamic impact of cycling postures on drafting in single paceline configurations. Computers & Fluids, 257, 105863.

A skier 5 meters behind another skier is still benefiting from drafting

Even if this seems impossible to many, the way aerodynamics work has a very large influence on the amount of energy we need to dispense. In biking the cycling federation has rules about where a camera motorcycle can ride around a biker. Research suggests that for bikers there are still some benefits even if a motorcycle is 20 or more meters in front of a biker. In running there are still relative power reductions even if running 5 meters behind another runner.

Interestingly, having a skier or runner behind the leader also reduces the drag on the front person. In skiing, the size of the athletes further influences drafting effects: a smaller skier benefits more from drafting behind a taller skier than vice versa. For example, a wind tunnel test on roller skis showed that a 1.57 m-tall female skier saved 10% of her metabolic power when following a 1.88 m-tall male skier, compared to skiing alone. These savings dropped to 5% when she followed another female skier. This highlights a substantial, often underappreciated advantage of drafting - and only some skiers know well how to exploit.

A picture of skiers double poling in a line

Other variables worth considering

  • Wind patterns can vary significantly, especially in open areas versus enclosed city settings, affecting drag differently.
  • Not all skiers have the same frontal area or drag coefficient during the race.
  • The lead skier often sets the cadence, which can influence the ski efficiency of those following.
  • During sprinting the sprinters gap can be utilized when a skier leaves the track behind another skier in the last minute in order to benefit the most from drafting and have a surprise effect advantage.

Key Takeaways

  1. Doubling your speed increases air resistance by approximately a factor of four, meaning drafting becomes increasingly beneficial at higher speeds.
  2. The optimal position in a line of skiers is third, where wind drag is significantly reduced. Further back, the reduction is only marginal, and it becomes harder to respond to moves in the peloton.
  3. A skier positioned 5 meters behind another skier still benefits from drafting.

If you are interested in the detailed insights behind this blog post and would like to learn more about our internal research, please feel free to reach out via our email contact@archinisis.ch.

Sources and Further Reading