Specialized’s latest aero innovation is not a bike, a wheel, a skin suit, shoe cover, or helmet; it’s a wind tunnel at the company’s Morgan Hill campus. The visually striking new facility will immediately become central to the company’s ongoing mission of improving aerodynamics across a broad range of its products, and makes the company the only bike brand with full control over its own aero testing.
In the past, like other bike companies interested in measuring their bikes’ aerodynamics, Specialized engineers traveled with their prototypes to test facilities including the A2 Wind Tunnel in North Carolina. To build a tunnel that could match A2’s precision, Specialized recruited Chris Yu, a PhD candidate at Stanford University in the field of High Fidelity Flow Simulation. Yu worked with longer-tenured Specialized employees Mark Cote, Chris D’Aluisio, and Chuck Teixeira to design and develop the tunnel. Between them, the four brought more than 20,000 hours of wind tunnel experience to the project.
Housed in a part of a warehouse that was once used to mold water bottles (and still houses a facility for screen printing them), the tunnel is about 30 metres long, with a test chamber that’s 9 metres long, 5 metreswide, and 3 metres tall—large enough, says Specialized, to test four or five riders in a team time trial formation. Like some other low-speed wind tunnels, Specialized’s facility has a “pull” design that uses six 75 horsepower fans positioned at the back of the tunnel to suck air through the horn-shaped inlet. Once inside the tunnel, air flows through an 20-cm thick hexagonal honeycomb that smoothes out turbulence as it accelerates toward the test chamber. Finally, before hitting the test subject, air passes through a mesh screen for further smoothing.
Specialized said it has tested air speeds as fast as 62 mph (100kmph), and that the tunnel is capable of even higher speeds—and of speeds as slow as 5 mph (8kmph). At the back end of the tunnel, a series of eye-catching carbon forms help to speed air out of the tunnel to avoid a build up of pressure against the back of the tunnel, which can distort data and has proven problematic in other tunnels with relatively small test chambers (aerospace tunnels have a much larger test chamber).
Like most wind tunnels, there’s a platform in the centre of the test chamber, to which fixtures are mounted for securing subjects. Specialized’s platform can rotate through 360 degrees to facilitate data collection at different yaw angles. Underneath the platform is a complex balance that works in a similar manner to your bathroom scale; the only difference being that instead of measuring downward pressure, it measures forces pushing against the test subject. Yu’s algorithm then uses that metric to calculate drag figures.
The company is tight lipped on the balance, which was designed by Chuck Teixeira, but said that they believe it will be as accurate as the system in place in the best wind tunnels currently used for cycling, and will exceed others.
The company plans to use the tunnel in two ways: First, product engineers will be able to quickly evaluate new designs—and the company hinted that anything from road bikes to downhill rigs would go into the tunnel. Second, Specialized will use tunnel data in conjunction with Computational Fluid Dynamics software, Specialized Racing Data Acquisition System (a bike-mounted telemetry collection unit), and Body Geometry Fit tools to help sponsored athletes achieve a position that’s both aerodynamically efficient and practical in real-world situations.
Not just for high-end athletes and engineers, lessons gleaned from the wind tunnel will eventually make their way to your bike shop through the company’s Specialized Bicycle Component University dealer education group. Even if you don’t have access to your own private wind tunnel, some lessons learned can be relayed to fit studios, so that you too can benefit from Specialized’s investment.