[Daryl]

Folks - I swear I am not trying to shake your faith with this forward bending thing, but it is an artifact of the physics. I personally don't see how it materially changes the model that TGM proposes.

Just for the sake of completeness, I will add some references here because people may think I'm making this up.

1) Cochran & Stobbs, "The search for the perfect swing", 1968.
See Figure 32:5 Caption "How bending the shaft forward, as it always is just before impact, closes the face of the club....."

2)Jorgensen, "The Physics of Golf", 1994
See Fig 12.1, also last paragraph of Chapter 12 - "...I think the flexing of the shaft forward as the clubhead comes into the ball is a general characteristic of the golf swing. Photographs made with the use of a focal plane shutter must be ignored in this context. There are few photographs in golf literature made with stroboscopic light sources, but of those I've examined, all of them show clubs flexed in this manner."

3) Horwood (Technical Director Apollo Golf Shafts), "Flexes, Bend Points and Torques", Golf The Scientific Way, 1995 pg 103-108
See Figure 1 "Shaft Bending in Typical Swing" and accompanying text- "Although over half of the 2 second time interval covered by the trace in Figure 1 is taken up by the back swing, it can be seen that the shaft goes from being bent backwards (by about 3 inches) to being bent forwards (by about 2 1/2 inches) in the instant before impact with the ball."

4) Butler & Winfield (True Temper Sports), "What Shaft is Best for You?", Golf The Scientific Way, 1995 pg 113-115
See Figure 1 for deflection curves of a shaft. Accompanying text- "During the load up time, the shaft first loads or deflects anywhere from 2 to 7 inches for a driver. The shaft then unloads and kicks forward at impact."

5) Wishon, "The Search for the Perfect Golf Club", 2005
See Chapter 4 under Three Myths-
"Myth number Two-The second myth is that the clubhead sometimes(usually? often? always?) will "lag behind" just before impact with the ball. .....The release of the wrist-cock also applies something called centrifugal force to the club. That centrifugal force combined with the arms slowing down and the club speeding up causes the shaft to begin to bend forward. And because the arms DO slow down when the wrist-cock is released, the shaft HAS to bend forward before hitting the ball."

Excellent post. I can appreciate the amount of work you have researched. However these authors are merely stating observation, not science. They fail to explain why, or state anything other than conjecture.

There is one more Author to consider.

See 6-C-0 #2. There is a reason for that parachute.
6-C-2-A. If the Pressure Point pressure that produced the initial Clubshaft flex is maintained it will maintain the flex also.