Club Balancing – "Swingweight" and "MOI" Matching

I recently took a big step in moving toward being able to make better “matched” golf clubs for my golf club clients. I purchased a device called the “MOI Speed Match” system from Tom Wishon golf. Tom Wishon has long been a proponent of using MOI matching instead of Swingweight matching of golf clubs – particularly for irons.

MOI matching and Swingweight matching of a set of irons are based on the same premise – having the full set of irons feel the same when you swing them.

Swingweight and MOI are based on somewhat different principles….

SWINGWEIGHT – I believe the concept of swingweight has been best defined by Ralph Maltby of Golfworks – “the measurement of a golf club’s weight about a fulcrum point which is established at a specified distance from the grip end of the club.” Swingweight is all about the weight distribution between the head of the golf club and the grip end of the golf club. Increasing the head weight and increasing shaft weight make swingweight increase, increasing the weight of the golf grip makes swingweight decrease. A relative weight scale was developed to denote different swingweights – so a D1 swingweight is larger than a C6 swingweight.

MOI – this is an actual physical measurement that is made for a golf club, it has dimensional units of mass/(length*length). It is a measure of how easy or difficult it is to swing a golf club. Interestingly, the weight of the grip has little if any influence on the measured MOI of a golf club.

How do swingweight matched clubs differ from MOI matched clubs? If you have a set of MOI matched clubs, you will find that the swingweights of the higher irons are lower than the swingweights of the shorter irons. Some fitters actually attempt to approximately MOI match a set of clubs by “progressive swingweighting” – increasing the club swingweight by typically 1/2 swingweight point between clubs – for example, the 6 iron swingweight would be 1/2 point higher than the 5 iron swingweight.

Proponents of iron swingweight matching believe that you should determine the best iron swingweight – which produces the best performance – and keep that constant for your main irons – for example 5 iron through 9 iron. Most swingweight proponents I believe feel that the wedges should have a bit higher swingweights than the other irons.

Proponents of MOI matching believe that you identify the best iron MOI for the player and then build the full set of irons to that MOI. They also believe that if you have a set of MOI matched clubs, that you can ask a player to swing their 5 iron and 9 iron with their eyes closed and they will not be able to tell you which one they are swinging.

So why am I making a commitment to moving to applying MOI matching in all of my iron fittings? It is largely from feedback from some of the most influential clubfitters in the country and the world. I am aware of one fitter who has done more than 1,500 MOI iron fittings with excellent results, and of another who has done hundreds of fittings and had only 1 poor result. I also recently learned that MOI matched clubs are starting to make their way on the professional golf tours.

Having golf clubs that feel the same when you swing them to me is an edge that golfers should have available to them.

Tony