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View sample of Speedplay test. Result: Drag Coefficient (CDA) of 0.237
View sample of Shimano test. Result: Drag Coefficient (CDA) of 0.243
View sample of Look test. Result: Drag Coefficient (CDA) of 0.243

 

In recent wind tunnel testing, Speedplay has discovered the aerodynamic importance of clipless pedal choice. Our goal in the wind tunnel was to determine the extent to which pedals affect the aerodynamic drag of a racing cyclist and to convert the raw data so it could be easily understood. The first known wind tunnel test of clipless pedals, conducted at the San Diego Air & Space Low Speed Wind Tunnel, www.lswt.com , established a notable difference in the coefficient of drag when comparing Speedplay pedals to other brands.

Cycling component manufacturers have increasingly used wind tunnel test data to evaluate and improve their products. However, a major challenge has been to accurately simulate real-world racing conditions in the wind tunnel. This is because the testing of a single component by itself raises questions as to whether or not the component will perform in the same way when installed on a bicycle and used outside of the tunnel.

With this in mind, we mechanized a life-size, lower-half of a mannequin so the mannequin, rather than a person, would pedal the bike. A mannequin was used to ensure repeatability of the tests by eliminating human variance. We purposely used only the lower half of the mannequin in an effort to also eliminate as much “extraneous hardware” as possible from the test. By mechanizing the mannequin’s legs, we were able to test the pedals in a life-like setting with the headwind and wind turbulence a cyclist would typically encounter during competition. In each five minute test, the robotic cyclist pedaled the bike at a cadence of 100 rpm and at a normalized wind velocity of 30 miles per hour.

Speedplay Zero pedals bested the other two pedal brands by posting lower coefficient of drag scores on both 3-hole and 4-hole shoe sole mountings. While the two other brands posted the same coefficient-of-drag score of .243, Speedplay pedals produced a score of .242 (with a 3-hole standard mounted cleat) and a significantly lower drag score of .237 (with a 4-hole standard mounted cleat). The reduction in wind drag of Speedplay pedals on a 3-hole sole, when converted to time saved, results in an appreciable advantage of 5.5 seconds per hour. By contrast, the reduction in wind drag of Speedplay pedals on a 4-hole shoe, when converted into time saved, results in an incredible time advantage of 33 seconds per hour. We suspected that Speedplay pedals would prove to be more aerodynamic than the other pedals because of their visibly smaller frontal area, but even we were surprised by the difference when the pedals were aerodynamically optimized by a 4-hole mounting pattern shoe sole.

By using available data to put this speed advantage into perspective, the 33 seconds of speed gained when using Speedplay pedals is equivalent to the speed gained when switching from a standard front wheel to a deep-profile, aerodynamic front wheel. It is also double the roughly 15 second per hour advantage gained by switching from a standard front fork to a bladed aerodynamic front fork.

This aerodynamic advantage is of importance to a cyclist because it is easier to gain speed by reducing drag than by increasing power. The result is also good news for speed seekers who appreciate good value, since a change to Speedplay pedals is an inexpensive way for a cyclist to gain a considerable increase in speed.

 



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