High balance point makes shaft easier to swing for more power, control

A current buzzword in the golf equipment industry is "MOI".  New driver heads, as well as other club heads, claim to have "high MOI", making them easier for players to hit straight. 

High head MOI helps on off-center shots by yielding less twisting of the head, producing less side spin. MOI stands for Moment of Inertia, which is technically defined as a body's resistance to angular acceleration about an axis.  As an object gets larger, or heavier, or as the weight is distributed farther away from the center of gravity (CG), the MOI increases.  When used to describe a golf club head, the MOI is measured about the vertical axis through the CG of the head. 

To better illustrate MOI, think of an ice skater spinning in a circle. If the skater's arms are pulled close to her body, she has a low MOI, and her rotational speed is fast (because there is little resistance to rotation).  But when the skater's arms are extended, she has high MOI, improving her balance, and slowing her rotational speed. 

As MOI is increasing in golf club heads, it is placing more and more load on the golf shafts.  Driver heads have traditionally weighed around 198-200gm, regardless of how big they are.  The first metal drivers were about 145 cubic centimeters (cc).  With this small size, the CG of these heads was quite close to the shaft axis, and the MOI was low.  As the heads started to grow in size, even though the weight of the heads remained the same (198-200 gm), the CG of the heads moved farther away from the shaft axis, and the MOI of these heads increased. 

Now that driver sizes are maxing out at the USGA stipulated limit of 460cc, traditional shaped driver heads have an MOI of up to 5000 gm-cm².  But the USGA has set a maximum MOI limit of 5900 gm-cm², so head manufacturers still trying to increase the head MOI by using different head shapes to reposition the weight.  Also, many of these new geometry heads are being made slightly heavier (203-204 gm), which again increases the load on the shaft.  These changes increase shaft loading in all 3 important directions.  It affects the shaft performance in torsion (twisting around the shaft axis), bending in the swing plane (affecting the effective loft of the club), and in the drooping plane (affecting where on the face the impact occurs).  So it is imperative that a shaft is designed to handle this increased load.  Additionally, the extra few grams of weight now being used will make a club with a slightly higher swingweight, unless somehow offset by the shaft.

The new UST Proforce HMOI shafts were designed specifically for the added rigors of new "high MOI" heads.  With all of the benefits that you get with these new heads, you want to make sure that the shaft has been designed to work along with the head. 

• § The Proforce HMOI has been stiffened throughout the shaft to be able to handle the extra loading of these MOI heads. The tip section is exceptionally stable in both torque and flexure to minimize the effects of twisting, lag, and droop, providing solid impact for improved control and shot dispersion.
• § The Proforce HMOI shaft has a higher balance point to offset the extra head weight of the new heads, often referred to as club heft. This balance point shifts the weight of the shaft farther into the hands, allowing the club to maintain a standard swingweight, even with a heavier head. For example, this allows the 73-gram shaft to swing like a 60-gram shaft, while allowing a strong, aggressive swing at the ball.
• § The Proforce HMOI shaft increases the MOI of the "entire club" about the club's center of gravity.You might ask why this is good, since higher MOI decreases rotational acceleration. While the club has a higher MOI through its CG, it is not rotating about its CG. The club is actually rotating about a hinge near the butt end of the shaft, so we should be concerned with the MOI about that location. The extra weight in the hands provided moves the CG of the club closer to the hands, which actually makes the MOI of the club "about the axis in the hands" to be similar to a standard weight driver head with a standard balance shaft. So the higher balance point makes it easier to swing faster than a typical mid-to-lightweight shaft.

The test results (remember - the lower the number the better):

Proforce V2 75 @ 45 inches D-3 = 2889

Proforce V2 HL @ 45 inches D-3 = 2855

Proforce HMOI 73 @ 45 inches D-1 = 2844