What is Waggle Factor

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Hi Frank,

You recently talked about wearing a glove and how it can affect the swing weight of a club, and I imagine wearing a watch might do the same? But my real questions are: What is swing weight? How does it affect the quality of the swing or the results? And how do I know/figure out what is the proper swing weight for me?

Thank you very much

– Brian

Brian,

To your first question; What is swing weight?

A great amateur golfer, Francis Ouimet, won various events which included the U.S. Open in 1913. He selected his clubs based on feel – an undefined term but most of us seem to have a general idea what it means. If you waggle the clubs in your set, they should all feel the same, i.e. have the same waggle factor.

Because Francis Ouimet was such a good golfer, his clubs – matched by feel-- were used to develop a balance system. This was done by hanging a weight (approximately 16 ounces) on the grip end of each club and finding a common balance point (fulcrum) from the butt end for each club. This balance point was 14 inches from the butt. Thus, the swing weight system was born in about 1920 and still used today. The swing weight is not described as the amount of weight needed to balance a club but by an alpha-numeric table such as D2 or C9 etc.

Swing weight is a questionable system for several reasons. First, it implies a dynamic measurement which it is not. Second, it can be abused by back weighting or adding weight down the shaft purely to get the same or desired number. Third, it is not very well understood.

Having said this, it must be noted that pure swing weight – variations in shaft length and head weight only – is a good first step in matching clubs, as this is closely related to the waggle factor a term I coined because it is so descriptive.

This waggle factor should be called matching by moment of inertia (MOI). This is a much better method of matching clubs as it takes into account the weight, length and is a true dynamic measurement. If you hold a club at the grip end and waggle it, you will experience a specific resistance every time you change direction back and forth. This relates directly to the MOI of the club about the axis you are waggling it i.e. the grip.

Now turn the club around, holding its head and waggle it. You will find the resistance to changing direction is reduced significantly. The MOI has changed and it feels different. Francis Ouimet, unbeknownst to him, was matching his clubs by the MOI method –  the waggle factor.

Most of us know, having mentioned it several  times in Q&As over the last year, that wearing a glove will alter (decrease) the swing weight of the club by about five points, but will not noticeably affect the feel of the club.
The glove will not change the waggle factor (MOI) measurably.

Brian, now that we are over that explanation, let me say that in general terms the higher the swing weight (pure swing weight), the heavier the head and the more resistance you will feel to swinging the club to generating the same head speed.

After about 400 years of trial and error we have found that a swing weight in the range of about D0 to D3 is a good number for most male golfers. Females generally migrate to about C6 to C9. This, in most cases, is because the shaft length is about 1-inch shorter than men but the head weight is about the same.

So Brian a good starting point for you – as for most men -- is about a D0 or D2.

I am sure we will soon be matching clubs by MOI, which uses a relatively simple scale and takes into account all those variables used in swing weight, but is a dynamic measurement and more meaningful.

Waggle your way around this one, Brian.

– Frank

 

Frank Thomas, inventor of the graphite shaft, is founder of Frankly Golf. Thomas is chief technical advisor to GolfChannel.com. He served as technical director of the USGA for 26 years and directed the development of the GHIN system and introduced the Stimpmeter. To email a question for possible use in an upcoming Let's Be Frank column, please email letsbefrank@franklygolf.com