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The Torqued Wrench: Aero is everywhere

  • By Caley Fretz
  • Published Apr. 25, 2012
  • Updated Apr. 26, 2012 at 12:35 PM EDT
Wind tunnel testing yields solid aerodynamic data, but can't account for real-world variables

Testing athletes

When a rider is added to the equation, the test subject is no longer static. That places more emphasis on field testing. Again, engineers run up against a dilemma: The more dynamic, the less useful the lab setting of the wind tunnel becomes, yet real-world testing struggles with the inability to control major variables, like wind and rolling resistance. That’s why many manufacturers and pro teams simply use both.

“When you add a rider, and use equipment with that rider, you treat that as a system, and we do perform that testing that on a track.” D’Aluisio

The velodrome allows D’Aluisio to account for small changes in body position that only crop up under high workload.

“At 40kph, (the riders) are plenty comfortable. At 45kph, their position changes. You can watch it change. At 50kph, they’re digging. At that point, we really see how the riders look when it’s most important. You can’t get that when you only use a wind tunnel.”

Ketchell also uses field-testing regularly with his athletes. He explained that when dealing with pro riders, time constraints are always a concern. Since there simply aren’t very many good wind tunnels around, field-testing is often the only option.

“There isn’t a lot of time in pro cycling, between races and training camps and media events. It’s a logistical nightmare to get to facilities and do testing. If you go to do testing, you take away from the rider’s time to train. That’s why we have developed better ways of testing in the field.”

That includes a device he calls the “BAT box,” which measures as many of those pesky real-world variables as possible, including wind speed and direction, temperature, humidity, and barometric pressure. This data, along with power figures, allows Ketchell to calculate drag. The result is a sort of portable wind tunnel.

“I built the BAT box to use in those circumstances when we can’t get to a wind tunnel, but need to test,” says Ketchell “We can test all the riders when we go to a camp in January and create a baseline, then test them throughout the year and see how injuries or new equipment affects the system.”

“When you’re in the wind tunnel, you can’t always get a feel for how the bike rides in certain positions,” he added, echoing D’Aluisio. “With field testing, done properly, we can.”

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Caley Fretz

Caley Fretz

Tech Editor Caley Fretz can usually be found chasing races along the backroads of Europe or testing bikes and gear in the mountains outside Boulder, Colorado. If you can't find him there, check the coffee shop across from VN World Headquarters.

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