Why Power (Watt/kg) Matters in Cycling and Cross-Country Skiing – And How Skisens Measures It

This rainy summer, many of us have been following the Tour de France, where Vingegaard claimed victory once again. He has no chance in the sprint and cannot match Pogacar’s explosive attacks, but he still wins because over time he produces the highest watts per kilo in the long climbs and in the time trials. Anyone who follows cycling knows that power (work per unit of time) is the single most important factor behind a cyclist’s success, and when climbing—where body weight must be carried—it is watts per kilogram that truly matters.

Growing Interest in Power Measurement in Cross-Country Skiing

Ski power, SkiErg performance and Vasaloppet correlations

In recent years, talking about watts in cross-country skiing has also become increasingly common. Even though the ability to measure skiing power is still limited, the concept is frequently discussed—appearing for example in the Swedish Ski Association’s latest performance profile¹. Many skiers aiming to improve their Vasaloppet finishing time have also seen Erik Wickström’s table showing how 5000 m SkiErg results correlate with Vasaloppet performance². The relationship between SkiErg capacity and skiing performance is clear on a group level—but it is equally clear that the spread in the data is large³. One of the main reasons for this variation is that the SkiErg is far more forgiving of technical flaws than actual cross-country skiing.

The Role of Skisens in Measuring Real Ski Power

Why SkiErg improvements don’t always transfer to snow

At Skisens, we love the SkiErg and consider it an excellent tool for tracking ski-specific strength and endurance. But to get the most out of SkiErg training, it’s crucial to regularly check whether your improvement on snow or roller skis matches your improvement on the machine. You can compare times, but that quickly leads to the inevitable question: did you actually get better, or were the external conditions simply more favorable that day? This is one of the main motivations behind our development of a power-measuring ski grip.

Calculating power without a power meter

If you don’t have power-measuring ski grips—or a bike with a power meter—you can still calculate your power output, provided you know the external conditions. You need rolling resistance, incline, and wind. In practice, this is nearly impossible to track consistently in training or racing, especially in flat terrain where air resistance dominates and even small wind shifts make a huge difference. Uphill terrain, however, is more manageable for anyone with a basic interest in mechanics. There are even enthusiasts who calculate Tour de France riders’ watts per kilo on different climbs⁴.

How Skisens Calculates Real-World Ski Power

Friction measurement, wind correction, and uphill power output

At Skisens we also work extensively with power calculations. We regularly measure on treadmills—where friction is known—to calibrate our sensors. We also perform outdoor measurements on certain climbs where we know the course profile. Our method is simple: we first ski the course with the Skisens grips to determine rolling resistance. If it’s windy, we add wind data to the calculation. Through this work, we’ve seen a clear pattern: strong cross-country skiers can generate equal or even higher power uphill outdoors compared to their SkiErg power. Less experienced skiers, however, rarely reach their SkiErg power output over the same duration.

Meet Skisens at Allum Hill Race – Real-Time Power Analysis

Live watt/kg calculations for every skier

On August 19th, we will be at the Allum Hill Race, organized by Sävedalens AIK in collaboration with Allum Shopping Center⁵. We have tested the rolling resistance of Skigo’s loaner skis and will use that data to calculate the real-time power output for all competitors under the day’s conditions. Come and race—discover whether you produce the same power uphill as you do on the SkiErg.

Guess the winning power and win a treadmill technique test

To make things more exciting, we have also measured the rolling resistance of the PU wheels used back when the race was known as “King of the Hill.” The course record in classic technique was 9:05, corresponding to approximately 3.7 watts per kilogram. With this year’s strong start list, we are expecting new power records.

Take a guess: how many watts per kilo will the winner produce, and what finishing time will that correspond to?
The closest guess wins a treadmill technique test.

1. https://www.skidor.com/download/18.4aa5445d186570d1523c393a/1677149887649/SSF_Kravprofil_A4_WEBB_uppslag.pdf
2. https://erikwickstrom.se/2016/12/30/5000-m-skierg-for-visst-led-i-vasaloppet-med-enklare-tabell/
3. https://erikwickstrom.se/2016/12/30/snittwatt-per-kg-kroppsvikt-pa-5000-m-skierg-vs-vasaloppsplacering/
4. https://velo.outsideonline.com/road/road-racing/tour-de-france/pogacar-vingegaard-and-victor-lafay/
5. https://allum.steenstrom.se/event-nyheter/event/allum-hill-race