MyGolfSpy Labs – The Iron Fitting Study (Part 2)

In part one of this two part series we gave you an overview of what you should look for in an iron fitting, as well as some of the key elements of any iron fitting. In part two we continue that discussion, and provide you with data from PING’s research that reveals the quantitative benefits of getting properly fit for your irons.

Written By: Erik Henrikson, Ph.D.

Set-Makeup

Determining the longest iron a player should carry, as well as the number of wedges, is an important part of iron fitting to ensure consistent gapping throughout the set.  For many years the tendency was for a golfer to purchase a full set of irons, with a longest iron typically being a 3-iron. Nowadays with the availability of hybrids and higher lofted fairway woods, sets will now start with a 4-, 5-, 6-, or even 7-iron. The transition point from a player’s longest iron to either a hybrid or fairway wood typically comes from the player’s experience regarding their long irons. A fitter should discuss with the player being fit their confidence level with their long irons, and start to transition a player into some long iron alternatives to optimize performance and gapping in that area of their set. Looking at some nFlight fitting data, the most common transition point in a set of fitted irons currently is at the 5-iron. Although this is the case, golfers may find it best to transition at another point in the set. There are some charts available that can help fitters and players identify a good starting point for a set-makeup leading to good gapping. Below is the PING Set-Makeup Chart that can help identify the proper long-iron transition points for players of various club head speeds.

Grip

Field experience and PING player testing have shown that grip size can have a bit of an influence ball flight, as well as influence the confidence a player has as they swing an iron. Grips are available in a wide range of sizes. There are a number of grip fitting charts available (like the PING Grip Chart) that provide a starting point for the fitting process and offers high statistical probability of an optimal size recommendation based on some measurements of the hand a fingers. If available, it would be recommended to try a couple different grip sizes to determine any differences in performance or feel.

Weight & Balance

The model, shaft, and grip can all influence the ultimate weight and balance that can be achieved with a set of irons. A fitter may choose to alter the way a club is weighted or balanced in order to help optimize performance. As a player, you may also find that you prefer a certain feel and weight in your irons. During a fitting this should definitely be part of the discussion as you are providing feedback to the fitter. Two of the primary ways the mass properties of a set of clubs are characterized is by total mass and swing weight.

The total mass of a club is exactly that; the combined mass of all the various components (head, grip, shaft, etc.). Swingweight, on the other hand, is the relationship between the club head mass and the overall length and mass of the club about a fixed fulcrum point. The fulcrum point is 14 inches from the butt end of the club. Swingweight typically refers to the relative head weight feel and is measured in alphanumeric units such as C9 and D0; higher letter-number values indicate a heavier swingweight. Longer-than- standard clubs will increase the values of available swingweight, while shorter-than-standard clubs will decrease the value of available swingweight. Graphite-shafted clubs generally will have a lighter overall weight. Typically graphite-shafted clubs with heavier heads will be assembled to achieve similar swingweight ranges as steel-shafted clubs at the same length. Standard swing weights will vary by model, shaft type and club length.

Overall, swingweight can have an effect on performance, influencing the way a club is delivered. In general, heavier swingweights and total weights tend to fight the miss to the left, while lighter clubs tend to fight the miss to the right. Most equipment manufacturers have dialed in swingweights for their iron sets that are targeted to provide the best performance for the overall population, but weight and balance should be part of the fitting discussion.

Performance Gains

So what type of performance gains can one expect to obtain through an iron fitting? As mentioned above, PING’s nFlight software is used by accounts around the world and gives us a great window into the performance gains that can be had through a proper iron fitting. Pulling up the last 200 fittings conducted at PING shows that player’s averaged an increase of around 10 yards with a properly fit 7-iron compared to the gamer they were using when they came into the fitting. As you can see from the chart, most all players gained distance.

Diving a little deeper into the data, the factor the contributed the most to the distance gains that were seen was ball speed. The average increase in ball speed when comparing the fitted iron to the player’s current gamer was 5 mph, which can be attributed to some, if not all of the elements listed in the previous section.

The other element of performance that typically experiences significant improvement during a fitting is dispersion and consistency. Most launch monitor and fitting software includes a method for visualizing groups of shots with a particular club. Over the same sample of fittings, the dispersion area decreased by 30% on average when comparing the fitted club to the player’s original iron. Just to show how significant a 30% decrease can be, two dispersion ellipses from a fitting where the dispersion improvement was 30% were overlaid on a green to give some perspective. Imagine you had a 170yd approach into the green pictured. Which iron would you prefer?

There are clearly benefits to be obtained through a proper iron fitting. As a golfer who may be planning to get fit for their next set of irons (if you’re not, you should be!), a working knowledge of the different things to looks for and the elements you should see being addressed during a fitting will ensure that you get the most out of the experience.