[Daryl]

Daryl,
Not sure why you haven't acknowledged Bernt's explanations of different RPM's for the left arm versus the clubshaft. I think he explained it clearly enough - If you have any left forearm rotation/upper arm rotation on the downswing - it will create greater RPM for the clubshaft than the arm.

I didn't acknowledge "Bernt's explanations of different RPM's for the left arm versus the clubshaft" because it's irrelevant.

Strap a board to your left Arm, Wrist and Clubhead. If they all stay against the board (Aligned) through the Impact Interval, they traveled at the same RPM. Strap the board to your left forearm, wrist and Clubhead and they travel at the same RPM.

Mike, do you "Understand"? RPM is not Turn and Roll. The Primary Lever stays Aligned regardless of the Turn and Roll. Maintaining the same RPM is necessary for Hinge Action but RPM is not Hinge Action. If the Left Wrist is Bent through Impact, I can still Hinge the Left Wrist however, the Clubface will be somewhere else. We need a Flat Left Wrist (RPM) so that anything the Wrist does, the Clubface will do likewise, and not something else.

The point to be learned here is that the Club, because of the Flat Left Wrist, must always travel at the same RPM as the Arms and reproduce the Hinging inherent in the selected Lag Loading procedure (10-19) per 4-D, 9-2 and 9-3, regardless of Clubhead Extension velocity. See 2-P and 7-18.

Thank you sooo much for the gracious Primer on the Left Wrist Vertical Cock and Uncock geometry - MPH. Why don't hold onto that thought while you learn about Horizontal Bend and Arch - RPM.

Maybe I'll buy you a "Taly" for your birthday. It's an RPM trainer. Right?