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Trackman and the center of mass

Even among experienced Trackman users, there exists the misperception that Trackman tracks the "center of mass" for determining its reported clubhead data, such as path and clubhead speed. However, radar can't possibly weigh and balance the clubhead to determine the COG, so Trackman must be doing something else. According to the most recent Trackman newsletter, it purports to track the geometric center of the clubhead, which Trackman considers a reasonable approximation of the clubhead's center of mass (btw, center of mass and center of gravity, or COG, mean the same thing):

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Of course, analyzing the shape of an object traveling in excess of a 100 miles-per-hour must be quite a technological challenge, and our research shows that Trackman's reported clubhead speed is typically more consistent with a point located well towards the heel and not at the clubhead's geometric center:

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A notable exception was the Callaway FT-i: Trackman's reported clubhead speed was more consistent with the Phantom-determined clubhead speed at the middle of the clubface. A look at the clubhead suggests why that was the case: it's big, square and flat, with relatively sharp edges.

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Here is the clubhead speed data for the FT-i; in this case, Trackman seems to think the geometric center of the clubhead sits to the toe-side of the center of the face:

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More typical is what we saw with the Krank Black Rage driver, swung by long-drivers Geoff Olohan and Tyler Kellett (ironically, the clubhead is white!). Shaped like a stealth bomber, it is harder for radar to see.

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Here is Geoff's clubhead speed data:

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Looking at the Phantom v. Trackman clubhead speed data, it appears that Trackman has guessed that the clubhead's geometric center is somewhere between the center and the heel tracking dots, favoring the heel. The heel and center tracking dots are 1.5 inches apart, so let's say Trackman believes the club's geometric center is an inch towards the heel. Geoff hit one in that location and below is the post-impact photograph as well as a screen cap of the ProAnalyst tracking. Does that look like where the clubhead's geometric center should be or where the center of mass belongs? No. But that's what Trackman thinks!

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Jeff