Swingweight Table From the table, the calculated force corresponds to a Swingweight of D7.8. Measuring the club in a Digital Swingweight Scale gives the same Swingweight of D7.8. The club used for this example is a TaylorMade 5 hybrid. The fact that a letter scale and a measuring tape can replace the Swingweight Scale, which has been utilized for almost a century, will come as a big surprise to the majority of golf club fitters. This ought to raise some concerns even for the die-hard Swingweight supporters. As the center of gravity does not enter any equations describing circular motion, the Swingweight of a body cannot be related to how a body acts under circular motion. Newton’s second law of circular motion states: Torque = Moment of Inertia x Angular Acceleration. There is, therefore, no relationship between Swingweight and how a golf club behaves when acted upon by a golfer. Ever since the Swingweight principle was developed in the 1920s, it has been the accepted method for matching clubs within a set, so they all feel alike when swung. In short, it is a measurement of the weight distribution of the club. And with the introduction of lighter shafts, grips, and club heads, the possibility of a wider range of Swingweights, and thus more inconsistency from club to club is greater. When Robert Adams was matching his set of golf clubs by waggling the golf clubs in a horizontal plane, he was in fact attempting to measure the moment of inertia of the club around the center of the grip. The moment of inertia around the center of the grip is henceforth referred to as MOIG. One can imagine how difficult it would be to adjust all 13 clubs until they all felt like having the same MOIG. There were no instruments available for measuring the moment of inertia at the time. Robert Adams made an instrument that would provide an indication of whether all the clubs in a set of golf clubs would have similar MOIG. The clubs used to develop the swingweight method all had similar wooden shafts. That is no longer the case. The Swingweight system is therefore even less useful today than it was 90 years ago.

There are a number of things that can go wrong in a golf swing. If the clubface is half a degree off, the ball can end up 20 meters off target. If the ball is hit 5 mm off the sweet spot, it will have a detrimental effect on distance and direction. The actions of, and timing of firing, the hundreds of muscles involved must be held in the subconscious memory of the golfer. One may think of this set of finely tuned actions as a software subroutine. Obtaining the required accuracy with one club, and embedding it in the subconscious mind, is an achievement. To create and memorize a different subroutine for each of the thirteen clubs in the bag is next to impossible. The golfer must also be able to differentiate the thirteen routines and call upon any one of them at random. With many years of endless practice, one may get close to mastering this at a subconscious level.

Even professional golfers at the highest level can win a tournament one week, and then miss the cut the following week. It is difficult to maintain the thirteen subroutines. Therefore, throughout the history of the game, people have tried to match golf clubs within a set so that they all will behave as intended, using one swing.  One subconscious subroutine could then be utilized for all thirteen clubs.  It is much easier to maintain one set of tasks rather than thirteen. Especially when they are so similar that it is difficult to tell them apart.

This discussion does not include the putter, the fourteenth club in the bag, as it uses a fundamentally different set of movement and does therefore not interfere with the subconscious skills of swinging the thirteen clubs.