In the real world, very few riders have the ability to maintain a speed of 50km/h for a length of time as they are simply not fit enough. The reality is on the open road, wind does not come in from a perfect angle, it's speed changes and things like street furniture (hedges, kerbs, passing cars, rider rocking from left to right) upset the airflow over the rider. Modeling this type of situation is called transient analysis. It is technically more difficult to carry out transient analysis both in CFD and in a wind tunnel. Most wind tunnels are not geared up to carry out transient analysis.
Wheel manufacturers are now using a weighted analysis of yaw angles and speeds to give an overall rating for their wheels. Bare in mind they can adjust their weighting to make their wheels look better!
A superior method of analysis is to carry out a transient analysis in a wind tunnel. This requires a wind tunnel with Horizontal and Vertical Louvres to add Swirl to the air before it hits the bike and rider. This allows a much more realistic estimate of drag to be estimated as it simulates road conditions.
- There isn't a ton of information on the "protocol" i.e. what yaw distribution was used. (scratch that, now included)
- There is some illusion made by the author to measuring "transient drag" instead of "steady state" drag.
- No tire information is given (scratch that, now included)
- The power differences between 30 km/h and 50km/h look about right
- Other than the occasional oddball, the ordinal rankings look about right based on depth.
- I'm guessing the "Bontrager 60mm" are the new Aeolus XXX 60mm rims as the D3 profile was not offered in a 60mm depth.
- I find it interesting that both the Bontrager and the (presumably) Aeolus XXX performed so well. They are both very similar in shape which is a somewhat "new" shape. I tend to believe the data that Trek Bontrager produces so that gives me some confidence in the ordinal results shown here.
- Flo wheels did not do well in this test which makes me wonder which version of their wheels were tested. The 45 is obviously the carbon model.
...I'll go get my popcorn.