This story was selected as one of the 15 best GolfWRX stories of 2015!

How a golf club feels is usually a very important attribute for golfers, especially better players, and there are clearly very big differences in feel across clubs. However, there are a lot of misconceptions about what really causes a particular feel.

It is important to note that the golfer defines what feel means to him or her and whether a club feels “good” or “bad.” The following is my attempt to explain a bit more about where feel comes from.

What are we actually feeling?

It’s probably best to start with a quick summary of what you feel when you take a swing. It’s basically a combination of two things: the sound created by high-frequency vibrations in the club head due to impact with the ball — typically a few thousand Hertz — and the vibrations that travel up the shaft, through the grip and into your hands. Those vibrations are much lower, typically tens to hundreds of Hertz.

Much of the sensation that is attributed to feel is actually the sound of the head. Any club has a distinct natural frequency and therefore a sound “signature.” Furthermore, off-center hits change that sound slightly and give a player the ability to discern the mishit, or what you would call feedback. We ran a test about 10 years ago that involved players hitting shots while wearing noise-cancelling headphones, and it became very difficult for them to distinguish any differences in feel from shot to shot or club to club.

The vibrations felt in the hands after impact are still an area of active research for us, but since they come up the shaft and through the grip they are actually more a function of those two components than the head. We still offer the Cushin insert, which dampens vibrations in the shaft after impact and helps a lot of golfers for whom those vibrations can cause pain and injuries. Also contributing to feel is the force felt in the hands during the swing and this is basically a function of the club weight and flexibility of the shaft.

These days in our player tests we will ask for feedback on how a club feels with regard to the weight and balance as they pick it up, how it feels during the swing, and also how it feels and sounds at impact. They can all be quite different.

What can be difficult for a club manufacturer is the range of sensations people want to feel. Some players want a lot of feedback to let them know they didn’t catch a shot in the middle of the face. Some don’t. Some like a powerful sound, others like something a bit more muted.

Do forged clubs really feel better?

There are some significant differences in sound and feel between most forged blade irons and most cast cavity-back irons. These differences, however, aren’t the result of manufacturing technique. Take a look at Figure 1 comparing the frequency response (basically the sound signature) for a forged 5-iron versus a cast 5-iron of exactly the same design from a paper titled “The Comparison of Forged Heads to Cast Heads for Golf Clubs” written by the Mechanical Engineering Department at Virginia Tech University. The conclusion of the paper was that for clubs with a similar material and a similar geometry there isn’t any real difference in sound or feel between forged and cast club heads.

We ran a similar experiment that has become semi-legendary over the years in the engineering department. We made S59 6-irons using the same basic material and geometry in cast and forged versions. A test was conducted with 15 of our tour staff and only one player was able to successfully identify which iron was forged and which was cast.

It’s about material and geometry

So if it’s not the forging process that leads to the soft feel, what is it? The properties that really affect the frequency of vibration are mass and the elastic modulus of the material. Elastic modulus is essentially the force needed to permanently stretch or compress a substance. This is similar to, but not the same as hardness. Within reason, harder and softer metals won’t necessarily sound much different — it depends on the elastic modulus. Titanium alloys can be made to have a similar hardness as steel, but a much lower elastic modulus. On the other hand, many of the different types of steel used in golf clubs have a somewhat similar modulus, but vary quite a bit in hardness.

The other property I mentioned, mass, makes the biggest difference in irons. If we’re comparing two 7-irons, the total head mass is likely to be very similar, but the placement of that mass will change the sound significantly. Figure 2 shows toe views of a typical cavity iron and a blade iron. It’s not hard to imagine that the iron with perimeter weighting (the cavity back) will vibrate at a different frequency to the iron with more mass in the middle of the club (muscle back). It’s the geometry of these clubs that differentiates their sound, not whether they are cast or forged.

The historical context

Clearly, the perception is still out there that a forged club feels softer than a cast club. Even here at PING we did an experiment recently where we took two identical S55 irons and etched “forged” on one of them. In the test, one in three players reported a softer feel from the club that had forged written on it, so just the word “forged” creates a particular thought in a golfer’s mind. The reality is that both forging and casting technology in golf have come a long way in the past few decades, and the lines between what manufacturers can do with forged and cast products have become very blurred.

I do still run into a lot of golfers who have the perception that cast clubs are harder and therefore can’t be bent for lie angle. They must have not seen PING’s 10-degree color code chart, which made its debut in the 1970s. The point is that perceptions take a long time to change.

The best thing golfers can can do is keep an open mind and actually experience the feel of different clubs themselves.