A Visit to the MIT Wind Tunnel

Report by Crystal Anthony

As a triathlete, I must focus upon improving not only my cycling fitness but also my aerodynamics to better my bike performance.  Any cyclist competing in time trials also relies upon these two components.  Recently I had the opportunity to visit the MIT wind tunnel to watch some testing and filming for Bicycling Magazine and to suit up myself for a ride in the tunnel to see what improvements I could make in my positioning on the bike.

After a parking attendant directed me down an alley off Vassar Street in Cambridge, with some vague reference to “that’s where they do the airplane stuff,” I found Building 17 with a huge, hourglass-shaped white structure tacked on the back.  The Sports Innovations lab bustled with activity – several MIT aerospace engineer students, Dr. Kim Blair, some local bike shop fitters, Alan Cote from Bicycling Magazine, and the test subject from Hot Tubes all were  busy preparing for the testing.  Computer screens displayed real-time numbers measuring drag, and sprinkled around the computers were files, boxes of bike parts, a flying suit suspended from the ceiling, model airplanes and helicopters, an old school telephone, and many other things I really couldn’t identify.  The wind tunnel itself looked much as I imagined.  It was the size and shape of an empty jet fuselage, and it opened into a pool-sized, circular mesh-covered face which emitted a stiff wind and enough noise to require ear plugs.  The bike mounted onto concealed rollers on the floor of the tunnel, with a special apparatus to secure it in an upright position.  Cameras captured the bike and rider from many different angles.

Testing began with a short ride to achieve baseline data.  Then, by observing the various video feeds, the crew implemented several different position changes and retested the drag.  Changes involved modifying the bike itself (raising or lowering seat height, extending the bars, bringing the elbow pads in or out) but also modifying body position (having the subject tilt the head back more, rest hands on top of bars rather than grip them, etc).  Other wind tunnel testing involves comparing equipment – wheels, helmets, skin suits, etc – but was not the focus of the cyclist’s or my visit.  Another consideration when modifying position is the event in which the athlete competes.  Time trialists are more exclusively interested in being as aero as possible, while long course triathletes also consider comfort and conservation of running muscles since they will be out on the bike so long and also must transition to a run afterward.  While it is impossible to test for power and drag at the same time, another factor involved is of course the fact that modifying someone’s position for aerodynamic purposes could affect the amount of power he or she can produce.

One point that stood out to me was that a key factor in reducing drag is being able to stay in aero position as consistently and as long as possible.  That is, when finding a position and selecting equipment, it is important to make choices that allow for mantaining form and avoiding things like sitting up and twisting head around.  For example, if your glasses require you to turn all the way around to see behind you, and you are looking back every few minutes, that extra drag can add up.  Or, even if your position is amazingly aerodynamic, if it is consequently uncomfortable and you are frequently standing or fidgeting around, that can be detrimental in the end.  Finally, one last lesson I learned is that the stronger and fitter the athlete is overall, the more optimum a position that person will be able to ride.  For example, the rider who tested before me was a cyclist and therefore the focus was on making him as spread out and aero as possible.  However, his upper body and core strenghth were limiting factors and he was not able to maintain the position that the tunnel testing proved was most aero.  Finding your limiting factors and improving them can provide free speed by allowing you to maintain a more aero position.  Greater flexibility and more balanced body strength, allow you to obtain a more aerodynamic position over a longer period of time, therefore limiting drag and enhancing speed.  By using a sport-specific resistance training program that enhances strength without adding bulk, it is possible to improve performance and also prevent injuries.

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