This was on the Wishon forum . . . I thought I'd post it for y'all's benefit and reaction. Tom Wishon is one smart cookie. Blake and Wishon need to meet someday! He's really close to speaking our language with the stuff below. Can y'all say extension of the lever assemblies???
The benefit of a shorter driver and woods can all be substantiated by physics and can only be overcome by those few golfers who are blessed with a superior athletic ability.
It all revolves around MOI - in this case, the MOI of the whole club as it rotates around your spine in the swing and how the longer length can create enough of an increase in the load on a golfer to potentially cause breakdowns in the golfer's ability to repeat a swing move and swing consistently.
As you may know from reading here, MOI is equal to mass times the length squared. Therefore, the greater the length of the club, exponentially that longer length is really multiplied because length is a squared quotient in the MOI formula. So the longer the club, the more load the club is putting back on the golfer. And if the golfer does not have the inherent athletic ability or swing ability to be able to keep this load small from a higher MOI club, what can happen is a breakdown of the golfer's ability to keep the club on plane, on path and within the realm of proper/decent swing timing.
Granted, we are talking about the average golfer here, or rather in my off the cuff opinion, possibly 70-80% of the people who play golf. Here's the specifics - In a proper swing, we are taught to create a wrist-hinge angle (can't write the word wrist c**k because of the bad word filter on this forum software!) at the top of the backswing, and then to hold on to that angle as long as possible on the downswing before releasing it to hit the ball. The reason why this is a proper swing fundamental is because when you do this, the club and its headweight is CLOSER to the spine, i.e. the axis of rotation for the MOI of the whole club in the whole swing. So with the wrist hinge angle held intact during as much of the downswing as possible, the distance the club is away from the spine is shorter and there is less load on the golfer from the club, and the golfer will achieve a higher swing speed.
When you begin to unhinge the wrist-hinge angle, you start sending the head mass farther away from the spine of rotation - more LOAD on the body from the club in other words. And with avg golfers, this load can cause you to shift planes, shift swing path, and of course unhinge the wrist-hinge angle too early - all of which are BAD things in the swing. The longer the club to begin with, the more potential for this all to happen to break down the swing.
Even though the total weight of a shorter driver built to say, a D1 swingweight, is higher than a D1 driver at a longer length, remember that in the MOI formula mass is not a squared quotient as is the length. So the body can easily accept a little more mass but not so easily accept a longer length when it comes to the load brought back on to the golfer by the longer length. And the only thing that can counteract this is pure athletic ability of the golfer to inherently have the swing mechanics and coordination to adapt to the higher load of the longer length club. If you don't have that built into the swing/body, the physics of this says you are risking a breakdown of the swing.
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