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How is club head speed calculated

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  • How is club head speed calculated

    If skytrak doesn’t measure club head speed, how does it derive a number. Also I briefly noticed on the TruGolf demo it seemed to give club face data?

  • #2
    It seems to do linear regression. This works (roughly) as follows:

    (1) Given the data that ST really does measure (ball speed, ball trajectory, ball spin) find a big external data set (e.g. Trackman data set) where all this is measured AS WELL AS real club data.

    (2) Do a lot of data fitting on the external data set along the lines of (e.g. - a bit simplified)

    CLUB SPEED = A*ball speed + B*ball trajectory + C*ball spin (*)

    finding the "best" (in some average sense) values of the coefficients A, B and C that correspond to real life over a large range of values

    (3) When ST measures ball speed, trajectory and spin, calculate and display CLUB SPEED using (*) now that you know the values for A, B and C

    If you do it more carefully and in more details than I have roughly described here, then it's possible to back the actual coefficients out using EXCEL.

    This works pretty well and accurately for a whole load of "standard" shots, but for some less ordinary shots (e.g pitch with a 9 iron, low stinger under trees with 6 iron, belly sand wedge etc. etc.) then the results will be way off and can give smash factors < 1 or > 1.5

    Hope this helps - there are of course many more exotic possibilities than just linear regression.


    • #3
      Thanks, the was really helpful


      • #4
        When I compare ST calculated club head speed to skypro measured club head speed, the values only match approximately 60 percent of the time and can be off as much as 10 mph when conflicting. I believe ST will give most a general idea of their club head speed, but not sure why so much emphasis is still being placed on this data. In my opinion, ball speed is a more important value


        • #5
          Agree Lynchdpm.

          Since swing to swing, it is not accurate, it is not something one can use for specific feedback.

          Having said that, since club head speed is quite consistent in the short term, you can work out it out by taking your best ball speeds for a given club and dividing by ideal smash (ie. pro average). Tour smash (as well as carry, spin, ball speed etc) can be found at this link:
          For driver, we all know that it is just under 1.5 (1.48 to be exact). 7 iron is 1.33 and PW 1.23. For example, if your 7 iron ball speed is 115, divide by 1.23, and you get 93.5 mph club head speed.

          If swing by swing club head speed is important, I'd pick up a Skypro or swing speed radar.


          • #6
            We take in all the variables. But we can't tell where you hit the ball on the club face, so we can only assume that you hit the ball in the center of the face. For center-struck shots, our club head speed is very accurate. The more off-center the hit, the less accurate our calculation will be.