I have a highly technical question for those who are up to the challenge. I have regular access to a Trackman and often use it for my own personal "fittings". Recently I have been playing around with my two driver heads- TSR2 and TSR3 both in 10* in the same shaft (HZRDUS Smoke Black 6.0). I was trying to see which of the heads was a better fit for me and tested each at 10* and at 9.25*. What I discovered was counterintuitive to what I previously believed.

In 5 of the 6 sessions where I compared a driver head in 10* and delofted to 9.25* (by way of Surefit adjustment), I found there was an increase in spin of between 100-250rpm. According to Titleist Club Fitting manuals, reducing the loft of a club should reduce spin (300rpm for every 1*, I believe). I have found this to be the case when comparing T100 vs T100s irons or comparing a 9* head vs a 10* head but it doesn't seem to hold true when loft is manipulated by the Surefit sleeve, at least in my case.

I am a 5 handicap and have a relatively consistent swing. When I compare the Dynamic Loft and Spin Loft numbers of the head in 10* vs 9.25*, I am more often than not seeing lower Dynamic and Spin Loft in the delofted head (9.25*) but it is resulting is higher spin for some reason.

I am curious if these result are consistent with with Titleist or club fitters have found. The only explanation I can think of is that when adjust the Surefit sleeve to deloft a driver, it raise raises the Center of Gravity which increases spin.