August 2004 eTECHreport - Welcome!
Common Sense Points to Use in Fitting
New Models (updated)
SAY “HI” TO A REAL HYBRID
(by Matt Mohi)
An Overview of What’s Changed in
Because clubmaking and fitting are technical subjects, it is all too easy to get caught up in the ‘minutia and details’, and in the process not be able to “see the forest for the trees.” As many of you know who have followed, read and learned from my golf equipment and fitting research over the years, I much prefer to use a “practical” or “common sense” approach when it comes to advising what combination of head, shaft, grip and assembly specifications are going to make the most difference in shot performance for the golfer. The following is a collection of some of the common sense points of clubfitting that clubmakers can keep in mind when things become too complicated in a fitting session with a golfer.
Since TWGT completed work on the first ever system for truly matching the Moment of Inertia of all clubs within the set, several hundred clubmakers have invested in the program and have been using it in their custom clubmaking. In complete honesty, not one clubmaker has reported to us that a golfer for whom they MOI matched their clubs has not liked the difference MOI matching made in the swing feel of all of the clubs in their set. Not ONE!
We know there are thousands of clubmakers out there, all of whom have a desire to build the best custom clubs possible for each golfer they serve. MOI matching is without question one very good way to achieve that goal. Look at it this way. If we or any other clubmaking company were able to magically develop a head or a shaft that automatically hit the ball much farther or straighter for all golfers, there is no doubt thousands of clubmakers would all immediately begin offering that head or shaft to their golfers. While MOI matching is not going to add 30 yards or ensure hitting 14 fairways and 18 greens per round, it can definitely improve the percentage of solid, on-center hits for all golfers – and it will bring a more pleasing sense of feel to all golfers with all of their clubs.
MOI matching has long been recognized among golf equipment engineers and technically minded clubmakers as being superior to swingweight – it will make all clubs in the set swing with precisely the same effort from the golfer and with the same swing feel. Thus what it offers to the golfer is the chance to play the game with greater swing consistency.
MOI matching is not a TWGT discovery. All we have done is to recognize its superiority to swingweight matching of clubs and develop a system to finally allow clubmakers to build real MOI matched clubs. Please do not think of our MOI matching system as being a “product” that we are “hyping” as if in competition with any other company’s products. It is real science that is proven to make all clubs in a set swing with precisely the same effort from the golfer to deliver the same exact swing feel.
You may ask the question, “If MOI matching is so superior to swingweight, why don’t the big brand name companies do it?” Major manufacturers of standard made golf clubs do not and likely will not offer MOI matched clubs because MOI matching is individually custom fit to each golfer, same as length, driver loft, or any other fitting specification. In other words, one standard MOI cannot fit all golfers. The major manufacturers can never build every club they make to custom specifications, thus they would never offer MOI matching in custom form.
• If you have not yet considered getting into MOI matching
in your custom clubmaking, you need to.
We know that swingweight matching has been around for nearly a century. We also know that traditional methods of clubmaking can be difficult to give up, because we all dislike change to some extent. But MOI matching is superior to swingweight matching, it will deliver better clubs to your customers, and it will provide you with a valuable point of differentiation to enhance your clubmaking reputation in your local market.
I have to admit that I am somewhat of an equipment snob. While I enjoy the sense of accomplishment in pureing a muscleback 3-iron, that pleasure drops and fades (which perfectly mirrors the shot I hit most of the time) when I have to reach into my pocket at the end of a round to settle a bet! The reality is that I don’t have the same swing I did when I was a kid and was constantly hitting balls and playing golf without a care in the world. Ah, the good ol’ days!
While I have enjoyed playing the cavity backs in my longer irons, and admit to feeling more at ease over the ball looking down knowing that I have the forgiveness of a Cavity Back design, it finally dawned on me last fall that there was an even easier way to go – and it took only one swing to open my eyes.
When we received the first testing samples of Tom’s redesign of the long iron hybrid, the 321Li, I quickly agreed to participate in the human side of the testing. I hurried through my regular warm-up routine and wasn’t fully in the groove when I took my first swipe with one of the 321-3 iron test clubs with the GI-335 graphite shaft. The ball soared way up high into the air – so much higher than my conventional 3-iron that I had time to turn to Tom and yell “Winner!” before the ball hit the ground.
Immediately, I knew that this club was in the “VERY easy-to-hit” category. Apparently a lot of clubmakers have found the same thing because the 321 hybrids’ success this year for clubmakers has proven that our initial experience was correct. I am convinced that if there were an award for the golf industry’s “Club of the Year”, no question the 321 hybrid with its matching GI-335 graphite shaft would give everyone a run for their money.
Headweight for True Long Iron Length and Distance
Clubhead Rear Center of Gravity (CG)
The 321Li vs. Other Hybrids
The first thing that really struck me was the strong lofts of the assembled OEM hybrids. We know that loft is the primary determinant in how high a ball will fly and strengthening them only makes this more difficult for the golfer. Additionally, the .370” tip minimizes how the Center of Gravity of the head affects the shaft bending. This isn’t to say that this club doesn’t produce good results for golfers, but it really isn’t a replacement for long irons as much as it is a toned down fairway wood with a larger tip diameter, which from an ease of hitting standpoint makes no sense for most golfers.
TWGT believes strongly that the purpose of a hybrid is to truly replace the conventional long irons with clubs that blend smoothly in with the other irons. Making hybrids as this major OEM does confuses the issues of distance between clubs.
Fitting the 321 Hybrid Long Irons
Hitting conventional long irons properly requires the following swing mechanics for success: 1) a higher than average swing speed ( >80mph with the 5-iron) to generate more backspin to help keep the ball in the air. 2) Never allowing the clubhead to pass the hands before impact. 3) Keeping the head down and well behind the ball at impact. Obviously, these are swing moves that only the most skilled ball-strikers possess. Therefore, most golfers can and should replace their conventional low-loft irons with the 321 hybrids.
The most common sense way to fit the golfer for the 321 hybrids is first to determine what is the longest iron that they have the most confidence in hitting. Generally speaking with low handicap players that would be the #4 or even the #5. With middle handicap players that may be the #5 or 6-iron. With high handicap players it usually is the #6-iron or even the #7-iron (hmmm, does that mean Tom has a 321-6 in the works??). After all, TWGT is all about making shotmaking as easy as possible. With the stronger lofts that the golf industry has moved to for all iron sets today, even conventional 5-irons are tough to hit solid and high a high percentage of the time. Thus clubmakers should know to advise hybrids up to the point of the golfer’s longest conventional iron with which they have the most confidence in hitting.
For the length, the 321 hybrids should be assembled to continue in the same 1/2” length increment increase up from the longest conventional iron they will retain in their iron set. With the weight bore in each 321 head, building to the same swingweight as the other conventional irons is easily done.
If you are performing real MOI matching using the TWGT MOI Matching
System, you will build the 321 hybrids’ MOI to match the
same MOI you determine is best for the golfer’s irons.
Last month one of the posts on our TWGT Clubmaker Forum posed the question, “What would you update and change the most from your 1997 book on fitting?” While I chuckled to myself at first when I thought about the new book I’d have to write in response to the question, I was immediately hit by how much things have changed in the world of shaft performance and fitting techniques.
I realize that in previous editions of the TWGT eTECHreport as well
as some of the issues of our print magazine, TWGT TECHreport, we have
written a fair amount about some of the more modern aspects of shaft
analysis, shaft design, performance and fitting. Because this is such
a hot topic to so many clubmakers, I wanted to offer an overview of
some of the most important changes in shaft fitting over the past
2-3 years all in one place, so that you will have a single reference
as well as another jolt to help you adjust your shaft thinking.
1. The Shaft’s Main Contribution in the Club is to Total Weight, Launch Angle and Feel, with a Minor Contribution to Dispersion.
There have been a few myths that have surrounded what the shaft contributes to the performance of the shot. In no way can the shaft add or enhance swing speed, nor can it cause significant changes in accuracy. First and foremost, the shaft is the primary determinant of the total weight of the club. Therefore, it is very important for clubmakers to think of shaft weight first when they are trying to achieve a much lighter or heavier total weight in the clubs to meet the strength and tempo requirements of the golfer.
Second, it has a medium contribution to the launch angle, and from that, the trajectory of the shot. However, the loft and the CG position in the clubhead are the primary specifications to consult when you wish to make a significant change in the height of the golfer’s shots. The shaft can enhance the desired trajectory by a small amount (1-2 degrees in launch angle) when the overall flex is fit traditionally to the golfer. What I mean by “fit traditionally” is that yes, it is possible to fit a golfer with a much too stiff, or far too flexible shaft and see more visible changes in shot height. Traditional fitting for the flex involves identifying an accurate swing speed range for the shaft, and keeping the golfer’s swing speed measurement within the range as stated for that shaft.
The shaft does not have a significant effect on shot accuracy. In
other words, the torque of the shaft can cause a slight change in
accuracy but not more than a single digit change in dispersion yardage.
Of course, if the torque is over 6-7 degrees and the golfer is physically
strong with a powerful, late release of the wrist-cock, accuracy could
be affected in a very measurable amount. But then too, this has to
be a common sense part of torque selection for the golfer. There are
PGA Tour players who use shafts with torque of 4 to 4.5 degrees and
do not suffer from misdirection problems. Thus for most golfers of
average-to-stronger swing ability, keeping the torque no less than
3 degrees and no higher than 6 degrees is a safe credo of fitting
that will never cause shot performance problems.
2. Butt Frequency Cannot Be Used to Rate the Stiffness of a Shaft,
nor as the Chief Determinant of a Shaft’s Swing Speed Range.
I will be the first to admit that yes, it sure would be easy if we could say that in a driver of 45” length, 250cpm is an R, 260cpm is an S and 270cpm would be an X. Sorry about that, but thanks to pushing the envelope of the shaft’s whole bending stiffness design, it is not possible to judge the flex of a shaft by its assembled club butt frequency only. Some shaft design companies, TWGT included, have begun to specifically manipulate the stiffness of the center, center and tip, and/or tip section areas of shafts so as to offset or enhance the butt stiffness of a shaft to achieve differences in the launch and feel characteristics. As a result, and just to cite one example, there are shafts today with an assembled driver butt frequency of 230-235cpms that are definitely considered an “R flex”, and not an L or A flex as the old averages for butt frequency used to indicate. Same thing with irons as well.
From this, it is also not possible today to accurately “calculate”
the swing speed rating of a shaft from the butt frequency. Again,
I confess to having helped develop the first ‘tables’
that compared butt frequency to torque to conveniently reveal a swing
speed rating for any shaft. Such tables are worthless today because
they are not based on true engineering formulas for bending characteristics
of shafts. And modern stiffness engineering of the entire shaft is
not properly taken into account either. In the end, swing speed ratings
today have to be created from real player testing, taking into account
differences in swing mechanics and shot performance of golfers.
3. The Player’s Swing Mechanics Which Specifically Relate to the Bending of the Shaft are Extremely Important to Reference in Shaft Fitting.
While shaft fitting principles of the 90s did begin to recognize the importance of comparing different golfer swing mechanics to shaft design features, not nearly enough importance was placed on this aspect of shaft fitting. Today, when you think about the performance contributions of the shaft being chiefly club total weight followed by shot launch angle, it is vital to know which moves in the golf swing dictate what type of shaft design.
The most important factors of the golf swing that relate to shaft fitting are (1) Swing Speed, (2) Golfer strength and tempo, (3) Transition from Backswing to Downswing, (4) Position and manner of wrist-cock release, (5) Position of hands/wrists at impact.
Swing Speed is still the starting point for eliminating shafts that are not suitable in terms of the shaft’s swing speed rating, provided the swing speed ratings are reasonably accurate in their estimation from the shaft maker or shaft seller.
Golfer strength and tempo is a major factor to consult in the determination of the total weight of the clubs, i.e. the weight of the shaft. It is also one of the factors contributing to the torque, as well as a final determination of the bend profile of the shaft.
Transition from Backswing to Downswing is important for selecting the shaft’s butt stiffness and overall stiffness purely from a standpoint of a bending feel that will be comfortable for the player.
Position and manner of wrist-cock release is all-important when it comes to the shaft’s contribution to the launch angle of the shot, as well as the feel of the shaft for golfer comfort and confidence. Golfers with a very early release rarely note a trajectory difference between different shafts, while golfers with a late release will.
Position of the hands/wrists at impact is an important aspect (along with the release) for predicting whether a shaft will or will not exhibit its launch/trajectory design for the golfer. “Flexing the wrists forward” at impact, in which the clubhead is ahead of the hands, will mean that all shafts will likely hit the ball the same trajectory for the golfer.
In short, ignoring the swing mechanics of the golfer in any shaft
fitting is a sure way to end up with a shaft selection that does not
perform or exhibit a feel to the golfer as hoped.
4. The Amount the Shaft Bends in the Beginning of the Downswing is Much More About Feel – The Amount it Bends in the End of the Downswing is More About Shot Performance.
Because golfers have to rotate the club 90 degrees on the backswing to make a proper turn away from the ball, all bending of the shaft at the very beginning of the downswing will be in a plane that will be 90 degrees perpendicular to the plane in which the shaft bends just before impact. If a golfer uses a shaft that bends a lot in the beginning of the downswing, it is very likely that the golfer will detect this action and may or may not prefer that feeling. But this bending action in the beginning of the downswing will NOT transfer to the plane that the shaft bends before impact. Thus there is no “load and unload” springing of the shaft.
All of the shaft’s bending just before impact, which is the action of the shaft that dictates the shaft’s contribution, or not, to the launch angle of the shot, comes from the golfer’s wrist-cock release. As the golfer unhinges the wrists, the arms slow down as energy is transferred to the club, which begins to accelerate in response.
This unhinging of the wrist-cock generates centrifugal force on the club, which is the means by which the shaft is able to bend forward before impact and thus contribute to launch angle. The later and more powerful the release and the softer the shaft’s overall flex and/or tip flex, the more the shaft can bend forward to thus increase launch angle. The earlier the release, the less powerful the release, and/or the stiffer the shaft overall or in the tip section, the less the shaft will bend forward before impact, and the less the shaft will contribute to the launch angle.
However, the shaft cannot bend forward any more than the distance
from the shaft centerline to the CG position in the clubhead. It is
because of this principle of physics that the shaft can only contribute
moderately to the launch angle of the shot.
5. The Shaft is Not The “Engine” of the Golf Club or Shot.
The shaft may be considered the “transmission” of the club, because without it, there is no movement of the ball. But in no way is the shaft the most important component of the club or the shot. It is the “transmission” because it transfers the energy and bending capability from the golf swing to the club. If you had to choose one component to be the “engine” of the club, it would have to be the clubhead. The reason is because the clubhead has far more control over the ball speed, the launch angle, the spin rate and direction of the shot than the shaft.
If a golfer changes shafts and finds that they cannot hit the ball as well with the same clubhead, it is primarily because of the change in the golf club’s feel, total weight, and weight distribution/balance/MOI. What confuses the issue so much to lead clubmakers to believe the shaft is more important than it really is? The answer is, the overall aspect of “FEEL,” which is comprised of the golfer’s many perceptions: from how much they feel the shaft bend, to the overall weight, balance and MOI of the club, and how that affects their swing motion and timing.
TWGT is absolutely committed to helping clubmakers unravel the mysteries of shaft fitting. While we have discovered a number of areas of shaft performance that have been new and informative, we know there is still work to do to present differences in shafts that are going to be clear and concise for clubmakers to be able to perform shaft fitting with more confidence. To that end we remain committed, and will continue to offer truthful information, not hearsay or myths, to help guide your shaft selection for golfers.