Why is it so hard to do wind tunnel testing in a meaningful way?

Triathlon Forum
1

tldr; Build a new wind tunnel, invite press to visit for advertising on the tunnel and your new bikes, do ‘standardised testing’ at 7.5-degree yaw and 50mph and publish data that does not reflect the real-world difference between bikes.

So Boardman promotes their new wind tunnel by pushing data collected at 40 and 50kph at 7.5 degree-yaw. (https://www.cyclingweekly.com/fitness/bike-fit/watch-much-faster-time-trial-bike-really-434360). They then report getting narrower doesn’t offer significant aero improvements but getting lower always does and that as long as the fit is identical the road bike with clips and TT bike are within 4 watts at 40km an hour. Only at ‘higher speed’ does the TT bike start to offer real benefits.

Did anyone stop to think about the flow of air over the rider at 7.5-degree yaw? Or that the relationship between rider speed and wind tunnel speed becomes complex as you move to higher yaw angles? Or that optimising bikes at 50pkh and 7.5-degree yaw is a not the correct way to build the fastest TT bike?

2

The way I see the article is it’s that rider trying some things and testing her assumptions, gaining some insight, rather than making statements about bikes in general. I don’t think they are publishing data, with all that this implies, they are just showing the different things she tried in a table. I think it’s pretty clear this isn’t an scientific experiment but an introduction to a wind tunnel.