Tour de France Physics: Wind Tunnel Testing


Over hours of racing, even a few grams of drag can be the difference between the top of the podium and missing out. For manufacturers as well as for individual professional cyclists, hours of wind tunnel testing help determine optimum configurations of equipment and positioning. During a day of wind tunnel testing, a cyclist may complete dozens of runs, in which bikes, wheels, helmets, skinsuits, and positioning are all tested and tweaked to find the best combination of aerodynamics.

But wind tunnel results don’t always translate perfectly to the road, where buildings, people, cars and other cyclists may interfere with the freestream. And, as any cyclist will attest, the wind is constantly shifting and changing speeds as one rides. The Garmin-Cervelo pro team has developed a rig to measure wind speeds and angles experienced by cyclists in real world conditions. (The exact components used are unclear, but probably include some form of Pitot tube or 5-hole probe.) As more on-the-road data is collected, wind tunnel tests can be improved by placing greater emphasis on the most common wind angle conditions. (Photo credits: John Cobb, Flo Cycling, and Nico T)

This completes FYFD’s weeklong celebration of the Tour de France and the fluid dynamics of cycling. See previous posts on drafting in the peloton, pacelining and echelons, the art of the sprint lead-out train, and the aerodynamics of time-trialing.

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