Thursday, June 17, 2010

C.O.R. (Coefficient of Restitution) is a measurement of how lively the face can be before it is deemed illegal by the USGA.

What was the COR of the old wooded heads? What is the COR of a one piece stainless steel cast iron head today?

.830 is the legal COR limit meaning that a golf ball shot out of an Air Cannon at the face of a clubhead at 100mph cannot rebound back any faster then 83mph or it is deemed illegal. Now they have a CT test (Characteristic Time) which is just another way of measureing face flexture.

Wooden woods with their array of different plastic to paper fiber to metal face inserts and normal 1 piece stainless cast irons both have a COR in the area of 0.770

In the history and evolution of COR as a performance factor in head design, designers didn't really become aware of COR all that much until around 2 yrs after the very first titanium driver heads came out in the early to mid 90s. Actually the first reason companies began to use titanium to make their driver heads was to enable them to make the head size larger than had been possible with 17-4 stainless steel, not because of the COR capability from titanium's strength to modulus relationship.

Titanium has a much lower density than steel (4.5 g/cc vs 7.6 g/cc) so this enabled designers to push the size of the driver head larger. Size was a big factor in driver design back in 1993-94 because Callaway had started this trend with their original stainless Big Bertha. When BB came out, it pushed the size of a driver from 160cc to 200cc and triggered Cally's marketing campaign of "bigger is better".

So the industry got into all this huff about making larger and larger drivers. And from that moving into Ti for the head material allowed them to do that.

It was only after a year or two that the industry started to take a look at the Ti drivers and realize, "hey, I guess this does hit the ball a little farther - wonder what is doing that?" And from that, then the industry found that titanium's strength to modulus relationship did have an effect on the COR, and from that, an increase in the smash factor for more distance.

Then from that point on, it became a matter of figuring out how to make the Ti heads so the faces could be thinner to keep pushing the COR up while still making sure the faces did not cave in, break or fail.

Also, In the 70s prior to the metal wood era, you would see companies use face inserts made from different hardness materials and saying the metal face insert hit the ball farther than the old paper fiber insert because it is so much harder.

Same thing happened in the early days of the stainless woods - they all were saying that the move to steel woods would bring more distance because steel was harder than wood.

Even today, with much better engineering knowledge in the equipment side of the business, you will still see such claims about harder being better, as in the case of maraging steel face woods you still see marketing departments try and push with totally false claims.

But in reality, what really happens when the face gives a little (pushes inward at impact with the ball) is the ball stays more round and doesn't flatten out as much at impact, thereby retaining more of its energy. Remember when you were a kid and "Superballs" were introduced? When you bounced them on pavement they bounced really high because they didn't flatten out at impact. Now drop a half inflated basketball on the pavement. It won't bounce back because it flattens out and loses all its energy. So a hard clubface that doesn't budge at impact will make the ball flatten more and the ball won't leave the clubface with as much speed therefore less distance.

Wednesday, June 16, 2010

Why will I play better with custom fit golf clubs?

The Performance Factors of Clubfitting from Tom Wishon:
"After spending over 30 years in golf club design and clubfitting research, I am absolutely convinced that every golfer can play better and enjoy the game more by being accurately fit into golf clubs which are custom built to offset the swing mistakes and enhance the correct swing moves of each individual golfer.

Since 1981, I’ve taught thousands of clubmakers the correct principles of custom fitting. In turn, I have received countless phone calls, letters and emails from clubmakers as well as their clients who realize the best set of golf clubs will never be bought in standard form, off the rack from a golf retail store.

Real improvement through custom clubfitting requires consultation with a trained clubmaker who knows how to translate each golfer’s need for game improvement into direct changes in the specifications of the golf clubs which address each area of improvement.

In Common Sense Clubfitting: The Wishon Method, we teach clubmakers that all of the possible game improvement desires of golfers can be summarized in the following ways:

•I want more Distance
•I want to improve Accuracy
•I want to improve shotmaking Consistency
•I want to change the Trajectory of my shot pattern
•I Want to Improve the Swing and Impact Feel of my Golf Clubs

There are a total of 23 different design specifications which can be altered and customized to come up with the right custom fit clubs for any golfer. That’s a lot. Actually that’s too many for any clubmaker to have to think about trying to fit for each golf club in a set. Through my 30+ years of fitting research I have discovered which of these 23 different design specifications will visibly address a change in the golfer’s Distance, Accuracy, Consistency, Trajectory and Feel with their clubs. And that’s what we teach custom clubmakers – to focus on the golf club specifications which will result in the greatest amount of positive game improvement in Distance, Accuracy, Consistency, Trajectory and Feel for each individual golfer and find the golf club specifications which will make that happen.

There are two types of golf club specifications the clubmaker needs to know.

"A" Effect Fitting Specification: An “A” effect golf club specification will create the most visible and noticeable change in Distance, Accuracy, Consistency, Trajectory or Feel. When an "A" effect specification is changed, even by a moderate amount, the golfer should experience a visible change in that game improvement factor the first time they hit shots with the club.

"B" Effect Fitting Specification: This is a golf club specification that will create a performance change which typically will be less than an “A” effect specification for Distance, Accuracy, Consistency, Trajectory and Feel. A “B” effect specification will typically display its effect visibly ONLY if that specification was poorly matched in the golfer’s previous golf club(s).

In short, the more "A" and "B" specifications which are addressed in the fitting, and the more those specifications are different from the golfer’s previous club(s), the more visible and dramatic the game improvement change for the golfer will be. That’s how real custom fitting is better than buying standard golf clubs off the rack.

I Want More Distance.
The “A” Effect Specifications on Distance:
•Clubhead Loft Angle
•Club Length
•Club Swingweight or Moment of Inertia
•Woodhead Vertical Face Roll (Driver only)
•Club Total Weight
•Shaft Weight

The “B” Effect Specifications on Distance:
•Clubhead Moment of Inertia
•Fairway woodhead Vertical Roll
•Clubhead Center of Gravity Location
•Full Set Make-Up
•Shaft Primary Flex
•Shaft Bend Profile Design
•Clubhead Face Design

I Want Better Accuracy.
The “A” Effect Specifications for Accuracy:
•Woodhead Face Angle
•Iron, Wedge and Putter Lie Angle
•Club Length

The “B” Effect Specifications for Accuracy:
•Clubhead Hosel Offset
•Shaft Torque (woods)
•Clubhead Moment of Inertia
•Club Total Weight
•Full Set Make-Up
•Grip Size

I Want to Improve Shotmaking Consistency.
The “A” Effect Specifications for Consistency:
•Iron, Wedge and Putter Lie Angle
•Woodhead Face Angle
•Club Length
•Club Swingweight or Club Moment of Inertia
•Full Set Make-Up

The “B” Effect Specifications for Consistency:
•Woodhead Vertical Roll Radius
•Iron and Wedge Sole Angle
•Iron and Wedge Sole Width and Sole Radius
•Clubhead Moment of Inertia
•Shaft Weight
•Grip Size
•Club Total Weight

I Want to Change the Trajectory of my Shot Pattern.
The “A” Effect Specifications for Trajectory:
•Clubhead Loft
•Driver Head Vertical Roll Radius

The “B” Effect Specifications for Trajectory:
•Clubhead Loft
•Clubhead Hosel Offset (wood, hybrid)
•Clubhead Center of Gravity Location
•Shaft Primary Flex
•Shaft Bend Profile
•Fairway Woodhead Vertical Roll Radius

I Want to Improve the Swing and Impact Feel of my Golf Clubs.
The “A” Effect Specifications for the Swing and Impact Feel of the Golf Club:
•Grip Style/Type
•Grip Size
•Club Swingweight or Moment of Inertia
•Full Set Make-Up
•Shaft Weight
•Club Total Weight

The “B Effect Specifications for the Swing Feel of the Golf Club:
•Club Length
•Shaft Primary Flex
•Shaft Bend Profile

A competent professional clubmaker will approach the custom fitting session by first determining which of the areas of game improvement are most important for each golfer – Distance, Accuracy, Consistency, Trajectory or Feel. Then by measuring the “A” and “B” effect specifications on the golfer’s existing set, the clubmaker can reference these “A” and “B” effect specs for the desired game improvement areas above, and know how much improvement IS possible for the golfer to achieve in an accurately fit set of custom made clubs. The clubmaker then proceeds to guide the golfer through a series of measurements and tests which combine with the clubmaker’s assessment of the “A” and “B” design specifications, to determine the exact specs for the new custom fit set.

That’s real custom fitting, and that is a major reason why custom fit is better than standard off the rack clubs every day of the week, and for every single golfer".

Monday, June 14, 2010

What's up with these really long length drivers these days? Can golfers really gain much distance from this increased length?

You may find this recent article by Frank Thomas quite interesting as he answers a viewers question on this very subject. For what it's worth, I don't swing a 46" driver any faster then a 441/2" driver. The last time I measured myself, I was actually swinging the 441/2" driver 1 mph no difference for me.

Posted: June 14, 2010
Hello Frank,

I was wondering if you could answer a question which has been of some concern to me recently.

I'm a Scottish pro and I give a lot of golf lessons. I noticed that many amateurs and even pros struggle with the driver compared to the likes of a 4 or 5-wood. Could it be that drivers are too long for many people to handle?

Yesteryear the driver was around 43.5 inches for a man and now some are 46 inches long.

Is there a maximum or minimum length that you would recommend for the average golfer?

All the best
– Iain


Driver length, has also been of some concern to me for some time only because it is being introduced for the sole purpose of increasing distance – the most powerful words in marketing golf equipment.

With today’s light weight and high strength materials; high MOI (Moment of Inertia), increased COR (Coefficient of Restitution), and advanced face design the is driver more efficient than it was ten years ago, and significantly more efficient than the clubs which were available to Jack Nicklaus in the 1960’s– his driver length was 42 ¾ inches long.

This efficiency is good for the game and golfers but if the length of the driver is increased one loses the benefits of the advances made in applying high-tech materials etc.

Iain, you are right and recognize what many teachers have experienced, i.e. that because of the increased length of a driver up to 46 ½ inches long – almost three inches longer than the 3-wood 43 ½ inches – it is difficult to control in spite of the all the advances in design.

We have learned, after many generations of club makers and millions upon millions of rounds played, that for every three degrees change in head loft, the length between successive clubs is approximately ½ inch – i.e. from drivers, to fairway woods and long irons.

Drivers used to fit this model for many years.

Yes, we are going to get increased distance but at the expense of accuracy and control.

My strong recommendation for the average golfer is to take advantage of the new technology along with being able to control your drives, score better and have more fun.

Jack Nicklaus had the opportunity to have a longer driver but as mentioned he selected a 42 ¾ inches. When Tiger did his best he had a 43 ½ inch driver. The average length driver on tour is about 44 ¾ inches.
So take your lead from the best in the world if you want to enjoy your game more and score better using the "Big Gun".

Iain, thanks for the question. I think it is going to help a number of golfers and may even have some influence on some manufacturers who are now negating some of the fine scientific work they are doing for the average golfer.

– Frank

Frank Thomas, inventor of the graphite shaft, is founder of Frankly Golf. Thomas is chief technical advisor to He served as technical director of the USGA for 26 years and directed the development of the GHIN system and introduced the Stimpmeter.