MOI: Resistance to Twisting Pt.2

Twisting is absolutely the main feature of the golf swing. Your body, hands, shaft, and club head are all twisting, violently, throughout the golf swing. Golf club designers have to take these and many other variables into consideration. While the marketing departments focus mostly on the club head itself, there are two other areas to look at closely, when looking at Moment of Inertia.

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In part 1 ( ) we went over how MOI works and how to affect it within the club head. Part 2, we are going to look at the shaft and the completed club.


Players irons are workable and are smaller; whereas game improvement irons are larger and forgiving.

One of the reasons for this is the measurement of MOI. In part 1 it was shown how MOI is greater the farther the weight is from the center of gravity or axis point. The greater the MOI the more resistance to twisting, in turn the more forgiving a club will be.

Players irons are workable because they are smaller, which means the weight is closer to the axis point, the golf shaft. The closer to the axis the easier and faster it is to twist the club head. Because of this if a ball makes contact off center it will fly significantly shorter. With a game improvement iron that work ability is lost. While they range in size, game improvement irons are significantly larger, creating greater MOI when compared to a players iron. The greater MOI limits the twisting around the shafts axis providing more forgiveness.


When you have made a swing change have you ever noticed how it is easier to see this change with a 7 iron then with your driver? Again there are many variables with this, MOI is one of the major players.

The longer the club, the heavier the club, the greater the MOI. This should help you understand why the driver is more difficult to square up. With the driver having a greater MOI is has greater resistance to twisting then any of the other clubs. While the driver club head is more forgiving then an iron head as a complete club the driver becomes harder to square at impact. This is just a small look into what designers have to look at.

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Published by Bryan Montgomery

Marketing is My Game | Golf is My Passion | Family is My Life I enjoy reading and writing when I am not doing any of my other many activities of life. This is my outlet to talk about the game I care for so much, golf has been with me since I was a young child. And yet I continue to learn new things everyday. Hopefully I can entertain and bring some of my passion for the game for others. - Bryan -

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