ST does not measure clubspeed it is calculated (with good accuracy). It measures ball speed with high accuracy. I therefore extracted my data and calculated bsCarryEfficiency, bsTotalEfficiency, csCarryEfficiency and csTotalEfficiency.

The PGA tour measures carry and total efficiency comparing clubspeed to carry and total distance.

For carry efficiency the 2017 range is 1.918-2.616, my average across my ST data is 2.4

For total efficiency the 2017 range is 2.391-2.936, my average across my ST data is 2.63

Fig 1 |

Having watched numerous youtube videos of various professionals I noticed a number of them were posting driver data with significantly greater carry distances than myself despite a similar or lower ballspeed. Spin rates and launch angle were similar so the distances should have been comparable. I therefore looked at other launch parameters and once again found myself looking into Spin Axis:

Fig 2 |

__Skytrak, Trackman, GC2/GCQ__Going back to my youtube comment I decided to add some extra data; I added my trackman data from my recent Skytrak vs Trackman test, and manually captured data from youtube to see how the data compared. All of this data was produced on GC2/GCQ from various pros and also some amateurs:

Fig 3 |

__Returning to Spin Axis__I then decided to reproduce the spin axis chart with the additional data and see how it compares:

Fig 4 |

Figure 4 shows the efficiency vs spin axis plot for the 3 data sets and I this this illustrates a few things:

1. The TM efficiency data is comparable to ST except the spin axis values are generally smaller. This was already noted in previous testing.

2. The range of spin axis measurements for ST and GC2/GCQ are comparable (more extreme than TM) so perhaps the ST isn't exaggerated compared to GC2/GCQ? Much more data would be required to prove this.

3. The GC2/GCQ is significantly more generous in its carry calculation, to the tune of 10 yards at my average ball speed of 155mph.