[jmessner]

What does HK mean in 2-E and 2-M-1 regarding a "prestressed" shaft? He seems to imply it's bent but I'm not sure in which direction. Also, the way I read it he is saying this condition will reduce Impact Deceleration(?).

The reason I ask is I've been into clubmaking a lot longer than TGM and on the face seems to conflict with my understanding of the physics of impact. For example, Cochran & Stobbs in "The Search for the Perfect Swing" showed that there was basically no influence by the player or shaft during impact and that the exiting ball speed is determined solely by the clubhead speed just prior to impact (assuming square contact etc.). This doesn't jive with the idea of "resisting impact deceleration" so I'm missing something.

Maybe I'm reading it too literally - he could be just trying to emphasize not quitting and reducing throwaway and such but he uses rather specific scientific terminology so I'm not so sure.