Deep Dive: Estimating CdA from Public Strava Data at the 2026 Dutch TT Nationals

The 2026 Dutch National Time Trial course was ideal for a bit of data nerding. The opening part of the course consisted of a long, straight section with smooth tarmac, wide roads, no corners and almost no wind. In other words: about as good as you can hope for when trying to compare riders using public data.

Using the Strava segment “NK tijdrijden 2026 - eerste deel” (≈4.60 km), I estimated CdA for riders who had public power data available and compared those values with the official TT results. It turns out to produce some interesting insights: not only into how aerodynamic efficiency varies between riders, but also into the relationship between power, aerodynamics and final performance. It even provided some useful context for my own ride.

One small caveat: there was a slight tailwind of just a few km/h on this section of the course. On the other hand, the opening part of the segment was on slightly rougher surface than the remainder. Rather than trying to perfectly correct for every variable, let's assume these effects roughly offset each other and focus on comparing riders under the same conditions.

Unfortunately, most of the podium riders did not include their power data (as always..., maybe they should try Grassdune🤔). But we do have some data for some of the podium riders in MU23 and top10 results in ME.

So let's dive in! I provided the results, sorted by CdA, for each category below. For reference: Remco Evenepoel's CdA (small rider!) is estimated at 0.16 and Filippo Ganna's CdA (big rider!) just below 0.19.

Men Elite
- Ard Stuiver recorded the lowest CdA in the dataset (0.173), despite finishing 21st. A good reminder that aerodynamics alone do not determine the final result: power production remains equally important.
- Maarten van den Berg stood out by combining a top-10 finish (7th) with a decent CdA (0.192) while also producing 386 W on the segment. This is arguably one of the strongest combinations of aerodynamics and power in the dataset.
- My own ride (15th, 0.195 CdA) was encouraging from an aerodynamic perspective, knowing the background on this bike build 😆.

Men Under 23
- The CdA values at the front of the U23 field are remarkably consistent. Jarne van de Ven and Michiel Mouris both estimated at 0.179, while riding over 400 W, illustrating how closely matched the top riders were.
- Ruud Nagengast posted the lowest CdA (0.175) despite finishing 17th, again showing that excellent aerodynamics cannot compensate for differences in power output over a full time trial.
- The U23 category has the highest concentration of riders combining sub-0.20 CdA with 400+ W, highlighting the depth of aerodynamic and physiological performance in this field.

Women Elite
- Very little data on top riders unfortunately
- Quinty Van Klink recorded the lowest CdA of the entire analysis (0.171), despite finishing 24th. Like the men’s field, this demonstrates that a low CdA does not automatically translate into a top placing.
- Sveva Klok appears to have one of the strongest overall combinations, pairing a top-20 finish, 257 W, and an CdA of 0.191.

This won’t replace a wind tunnel anytime soon, but it is fascinating to see how much information can be extracted from public ride data. Think again why many riders hide it. I'm digging my own grave here.

If you enjoy these kinds of data nerding articles, let me know!