Wind Tunnel Testing Key to Time Trial Success
Great performances against the clock are essential to any rider’s hopes of winning the Tour de France, and when you have to ride 32.3 miles (52 kilometers) as fast as you can, all by yourself, it pays to look for even the smallest ways to save energy, deliver more power, and slip through the air faster.
Cyclists have been testing equipment and riding positions in wind tunnels for about 15 years. Greg LeMond did it before winning the 1989 Tour by just eight seconds in the final time trial. The U.S. Endurance Track Team pushed the science of wind tunnel testing forward prior to the 1996 Olympics by spinning the wheels and cranks and having riders pedal against resistance while in the tunnel. Aerodynamics have become so important that modern cycling teams hoping to win major time trials and stage races make an annual pilgrimage to the tunnel to test new equipment and tweak riders’ positions on their bikes.
Last winter, several of my coaching staff and I joined the Discovery Channel Pro Cycling Team, some of their equipment sponsors, including Giro helmets, and the computer gurus from AMD for a few days of wind tunnel and velodrome testing in San Diego, California. We put team members George Hincapie, Paolo Savoldelli, and others in the wind tunnel to optimize their body positions on the bike. One of the biggest things to remember about aerodynamic testing is that the best position for cheating the wind may not be the best for producing power on the bike. To do well in real-world competitions outside of the tunnel, George Hincapie has to be able to pedal at full speed, breathe deeply, steer, look where he’s going, and continue doing all of that for an hour.
To find the best riding position, we put George on his time trial bike, started the fans, and checked his drag numbers (which provide a measure of air resistance) as he pedaled at a prescribed power output that mimicked race pace. In addition to looking at the numbers, we also checked with George to see how he felt. Then we’d move his saddle, his aerobars, or his arm position on the bars, and repeat the process until the drag numbers were low and he felt comfortable enough to ride like that for an hour.
Now, as much as I believe in science and numbers, I also know that races are won in highly unscientific conditions out on the open road. To prove that the changes we made in the wind tunnel would yield faster racing performances, we had equipped the Discovery Channel riders’ bikes with SRM power meters that have the same telemetry feature as the ones several riders are using in the Tour this year (Check out http://www.srmdataserver.de/Telemetry/ during the stages to see live power data from select riders.).
As we sat on the infield of the velodrome at the ADT Event Center in Carson, California, watching power output data in real time on AMD-powered laptops, it was clear that Hincapie, Savoldelli, and their Discovery Channel teammates were faster than they had been just a day earlier, even though their fitness was exactly the same. It was also clear that Hincapie’s winter training had been very productive; he was more powerful than he ever been at a February training camp.
So, what does all this mean for tomorrow’s time trial stage? Well, the first half of the stage is likely to be ridden into a headwind, where a better aerodynamic position can save a great deal of time. Then, when the riders turn into what is likely to be a tailwind run to the finish line, they’re going to need to be able to produce maximum power, and stay in control of their bikes, to maintain very high speeds. Every rider slows down in the final 9.3 miles (15 kilometers) of a long time trial, and the winner is often the rider who slows the least. Developing an aerodynamic riding position that is comfortable enough to stay in for more than an hour allows a rider to remain strong as his rivals fade.
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