Dear JET,
Most of what I do emphasizes the human body in action over a basis of good physics, and putter fitting is matching the tool to the body and its action. That is to say, a putter cannot simply be fit to a setup posture -- it has to be fitted to a stroke action and the body that makes it. So, a "well fitted" putter will be one that acts with sound physics and that is consonant with the golfer's stroke action and his body making the stroke. Some of these same notions have been discussed before on this
Forum post. The following discussion is organized in terms of 1. Sound physics, 2. Sound technique, and 3. Individual body features.
1. Sound Physics:
Putter head weight: The modern tendency is towards higher mass in the putter head and a higher total mass in the putter than in recent years. A typical putter head from the last decades of the last century weighed about 325 grams, and the overall putter weight (shaft plus grip) came in around 490 grams. Today, putter heads are creeping well above 350-375 grams and total putter weights are over 500 grams. The "Heavy Putter" tops out at 885 grams for total weight. The greater the mass of the putter head, the more "send" the same stroke gives the ball in comparison to a lighter putter, so a shorter stroke is used for the same putt on the same green in comparison to a lighter putter used with the same tempo on that putt. Also, the greater weight (mass) has a positive physics effect by increasing the inertial tendency of the putter to resist slight nervous mis-movements emanating from handsiness in the stroke and by increasing the tendency of the putter to resist lifting in the stroke.
Loft: The standard dogma is that balls on today's green sit perched in a small cup-like depression of grass and the putter needs to launch the ball up and out of this cup with approximately three degrees of loft. (I question the geometry implied in this image, as only the grass directly in front of the bottom dimple of the ball really matters, so it is more an issue of whether the grass poses a "ramp" or "wedge" at the start of the putt, and on today's tight bent-grass greens, there is not much of a "ramp" at all for the ball to "climb out of.") What I believe is that there is a desired "minimum loft" at impact that launches the ball on a specific green with the least hopping or bounding, with the quickest roll, with the least skidding, and with the least backspin. This is really "dynamic" loft, as your stroke technique may add or subtract loft from the putter design by the way you make the stroke motion and where in your stance the ball is played. Assuming you add nothing to the putter design so the "dynamic loft" matches the design's loft at address with the sole of the putter flat to the surface ("static loft"), there is probably one loft that best coincides with any given green condition. Bermuda greens and shaggy greens take more loft, whereas tight bent-grass greens take less. It's not a good idea to decide loft by rolling putts on a tight indoor carpet or synthetic surface and then taking that putter to your "average" public course -- the fitting needs to be specific to the courses and greens that you play. Here's a related
Forum post on dynamic loft as it relates to center of gravity for launch aspects.
Hosel and Face Balancing: The Rules permit bending of the shaft for the final five inches into the putter head, and metal machining technology allows crafting putter heads with the hosel all out of a single slab of metal, as opposed to drilling a hole into the metal head and inserting the hosel into the hole. The end result is a variety of hosel configurations, from "goose-neck" putters to rear-end hoseling to hosels that attach on the toe end of the putter. The physics effects of hoseling does not yet appear to be all that well understood, and appears to me to be a rich area for innovation in the next few years. Today, usually, if the shaft aims at the putter's sweetspot, regardless of bending in the last 5 inches, the putter will have "face balancing." This means balancing the putter at a point about 10 or so inches up the shaft from the head will result in the putter face aiming flat and straight up, like a waiter's tray. Ping putters from the 1960s and 1970s were balanced with head weighting and heel hoseling so that the putter head hung down at a 45 degree angle, toe-down. This is a game-improvement feature for use on the older greens of yesteryear, in which golfers used more of a gating chipping-like stroke on the shaggier greens with more loft in the face. The balancing favors the toe end of the putter, and in the strokes used then, this extra toe mass "helps" the putter fan open going back and then fan closed coming forward, sort of like swinging a pocket watch sideways on a short chain. Scotty Cameron has made this game-improvement feature one of his signature design components so that his line has heel shafting and 45-degree hanging toe-down weighting, and writes about his theories and designs for "toe flow" on his website. Logically, designing the putter to do something EXTRA that the golfer is not personally causing seems a little risky to timing and accuracy. Scotty Cameron recently joined the market trend toward center-shafted, face-balanced mallets with his very successful Red X2 putters, and these designs are completely inconsistent with the "game improvement" toe-flow designs of his writings. There are other balancing schemes as well, including the dynamic balancing of the putter not as perched on a fulcrum in the abstract but as actually used in the setup and stroke, such as Floyd Bernhardt's Positive putters, and the 360-degree perfect balancing of the Puku Belly putters by Simon Moore in which the putter face balances and remains oriented in any angle. For me, I prefer NOT to use a game-improvement design, as I don't really want any partners "helping" in my strokes.
Length and Lie: From a physics point of view, the longer out from the body the putter head is located, the more rotational velocity the same body action is able to create. In other woods, the "sweep" of a long broom is greater than that of a short broom, with the same body action. The fittedness of the length has something to do with not getting too far from the body for body-control of the end of the tool (physically and visually), on the one hand, and something to do with body posture and comfort for control and consistency and accuracy of action, on the other hand. In my view, as the lie angle flattens, the sense of keeping the putter head "lifted" off the ground out away from the feet (as opposed to simply suspended from the arms and hands) increases. This increase comes with increased muscle tone in the setup, which can adversely affect how you move in the stroke. The physics of interest is the tendency of the putter head during the stroke to want to drop in toward the feet and the "fittedness" of your setup posture and muscle tone to resist this without special effort.
Moment of Inertia: Every putter head design is a specific distribution of mass in 3D space (its shape and density). Within the Rules for club designs, putter designers nowadays incorporate mass distributions that maximize the "moment of inertia" of the putter head in motion. The moment of inertia or MOI is the resistance of the putter head to twisting forces about a given axis of rotation. (There is a different MOI for different axes.) The axis usually of concern is the vertical axis up thru the center of gravity of the putter head, which is online front-to-back with the sweetspot of the putter face, for twisting forces promoting rotations of the putter head and face "open" or "closed" during the stroke. A high-MOI putter resists these forces and helps keep the putter head and face moving square and online, and also resists off-center impact forces that would twist the face during impact. Heel-toe weighting schemes in more conventional flange putter designs do the same as these big-headed high-MOI putters of today, but the big-headed putters take the issue to a new level.
Center of Gravity: Dr Norman Lindsay in England has done marvelous work studying the physics of the relationship between height of center of gravity in the putter head in relation t the center of gravity of the ball as it produces certain skid-roll results. This
Forum post goes into considerable detail. You will see that Dr Lindsay counsels a COG in the putter head that is low in relation to the ball COG, combined with certain loft designs, to minimize skid and backspin on the ball at the outset, and thereby to promote efficient roll and touch and direction. Others advise designing the putter head COG higher than the ball's COG, such as in the "Inverted Mass" design of the Aserta putters of Michael Bonneau. I think tis is an area that needs a little greater clarity, but I also teach a slightly upward trajectory of the putter COG thru impact in relation to the ball's COG in the meantime (as opposed to a level blow or to a descending blow).
Face Treatment: Some people counsel soft faces to increase "dwell time" of the ball on the putter face, and others counsel metallic faces of different metals for certain "feel" and sound properties. Harold Swash's C-groove and the Taylormade "nubbins" putters are example of treating the face in a way so that it makes the face react more definitely to the cover material of the ball. Again, Dr Lindsay has some great data about this from a physics point of view.
Back Weighting and Shaft Vibrations: The shaft of conventional putters vibrates at impact and afterwards in a pattern that cancels out low in the handle. below this "node," vibrations increase in amplitude and above this node the vibrations increase in amplitude, but right at the node, the vibrations mutually cancel one another out and the handle is "dead quiet." The function of backweighting in the Balance-Certified Golf scheme is to move the node higher up the handle. The idea is that conventional manufacturers inadvertantly create putters that put the golfers hands in the middle of the handle but above the node, and the BCG system corrects this by altering the vibrational pattern of the shaft so that the node relocates inside the hands of the golfer. The backweighting also affects the overall weight of the putter, and its swingweight sense of balance in the hands and sense of putter head motion. Grip weight can also alter the properties of the putter in a similar way.
Shaft Flex: Some pros mess around with the flex or swingweight of their putters, but in the physics, the motion is too slow and the relative masses of putter head and ball at impact are such, that the "flex" or swingweight doesn't matter much at all in the physics. I personally don't encourage this approach to feel and timing, so a standard shaft is fine by me.
2. Sound Technique:
As you can see, the above "physics" in the design features of the putter are dependent upon your technique. So the order of the day is good technique first, and good physics for sound technique second.
The two most important points for sound technique are 1) a setup with the gaze straight out of the face, and 2) a comfortable and balanced hanging of the arms and hands so that the shoulder-frame action proceeds from the top of the body without interference from the chest or upper torso. The key ends up being the extent to which the golfer combines torso bend forward at the lower back with top-of-back neck bend in setting the head. Whatever combination that allows the golfer to gaze straight out of his face down at the ball and the sweetspot of the putter while also getting his arms hanging out enough so that the upper arms don't come int conflict with the chest / pectoral region during the stroke is fine -- balance and comfort are definitely advisable in combination with these biomechanical features of a good setup. The head tilt and lower back bend that gets the upper arms clear while looking straight to the ball promote a) good beside-the-ball targeting, and b) straight putts with simple biomechanics. Some golfers like to bend the head all the way so that the axis of the neck is horizontal to the surface, the back of the head is flush, and the eyeballs are physically vertically above the ball with a straight-out gaze. Others find this degree of neck tilt too tight, and prefer a slight forehead-up setting of the face to the ball that (combined with the straight-out gaze) results in the eyeballs being back inside a bit from the ball. In bending the lower back and canting the upper torso forward, the golfer is balancing his weight in a new manner on his feet. If he maintains even weight distribution in his feet heel-to-toe, the forward leaning of the upper torso has to be counter-balanced by the rear end protruding backwards above the feet, like a high-rise crane with a counter-balance on the back end of the boom. A tendency to weight favoring the toes or balls of feet can help some people control and stabilize the top of their body a bit, as the very slight sense of tipping forward evokes a response in the lower body to set and hold against any falling forward, and this is a definite stability that some people like as opposed to a more casual, simple balancing on the feet with even pressure heel to toe. I like to teach a balancing into a stablized setup of the top of the body, with emphasis on moving the shoulder frame smoothly in relation to a fixed but rotating pivot at the base of the neck.
Some people, emphasizing the stability of the lower body, like a stance that is slightly wide. The idea is to widen the stance so that the lower body prevents the body's center of gravity (inside lower abdomen just below the navel and back in the body perhaps 4 inches for most people) from wandering about in a small arcing trajectory during the putting stroke. Historically, some very great golfers have used narrow putting stances, including Bobby Locke and Bobby Jones. And ben Crenshaw has a little flex action in his rear knee in the downstroke. personally, I teach that if you emphasize stability in the top of the body throughout the stroke motion without too much concern for how the lower body helps accomplish this, you are probably well served.
Some people teach a weight distribution with weight favoring either the lead foot or the rear foot. This is usually coupled with advice about hitting down or hitting up on the ball or using hands ahead or a forward press of a certain grip form. I think this is all very confused, and prefer to disentangle what the body does simply and consistently from the putter face moving thru the ball. In my teaching, a simple setup and motion that reliably moves the putter face squarely thru a certain zone beneath the neck and face is primary, and then when the ball is located in the forward section of this impact zone, the ball gets in the way of a good, straight stroke motion.
So I teach balanced feet, a neutral grip form, level shoulders at address, and a stroke motion that bottoms out at the same spot beneath the neck in the same place and with the same tempo timing every stroke, regardless of the size of the backstroke. All putts are the same basic motion, even if some strokes are larger. Because of this, I don't have a stroke that is well-suited to goose-neck putters or other putters where there is some assymmetry in the shaft, the hosel, and the putter face. I also don't prefer hosels that enter the putter head well back from the putter face, as in the stroke I teach the putter face and the bottom of the stroke need to correspond, and having the hosel and the shaft reaching this bottom only later is disquieting and disturbs my sense of timing.
Other teachers advise using a pronounced forward press and hitting down on the ball in a gating stroke motion with rolling open and closed of the forearms. In this sort of stroke, the golfer is advised to use a putter with LOTS of loft, as the technique dynamically will be removing all but about 2 degrees of loft for the impact. This technique often also promotes using a 'toe flow" design in the weighting of the putter. I don't think this is the best way to putt.
3. Individual Body Features:
Properly fitting a putter to your stroke also entails taking into account the characteristics of your body. The relative lengths of body segments, your overall body shape (especially in the torso and gut), the inertial or mass properties of body parts, and the relative size of body parts in relation to the putter all greatly influence a good setup and stroke as well as the response properties of the putter physics for feel, accuracy, consistency, and fittedness to the green.
A man with big hands would not want the same diameter putter grip as a person with smaller hands. A man with huge arms would not have the same feel and inertial properties or even "send" in his stroke as another person using the same putter with less massive arms. A tall person with wide shoulders and a large upper chest has different balance issues and more "sweep" for the same movement in comparison to a more compact, shorter golfer. A person with a larger, heavier head is likely to prefer a different head tilt than someone with a smaller, lighter head. More rotund golfers have different capabilities in making a shoulder stroke clear of intereference between the upper arms and the upper chest. There are many more aspects to consider.
In addition, different golfers have different developmental histories. A person's body postures and characteristic motion patterns reflect the person's physical development over the years, whether shaped by outdoor work and field / team sports or by more sedate activities like working at a desk or driving a truck. Body muscle and connective tissue form the skeletal structures in accordance with the developmental history. Many cross-dominant golfers, for example, such as a left-eye dominant golfer putting right-handed, has a bias towards setting up with the feet and shoulders slightly open at address, with the neck axis slightly angled across the intended line of the putt top-of-head nearer the target, and a head roll that lifts the left eye vertically up in looking down the line to the target in the same vertical plane that includes the line of the putt on the ground (in a way that kinks the axis of the neck out of perpendicular to the shoulder alignment and sends the chin slightly farther away from the left shoulder in the head turn). Other golfers by use of the arms in lifting and carrying weight have a more pronounced angle in their resting posture between the upper arm and the lower arm due to muscle tone. Golfers also differ in the way their hips orient -- with not very many golfers standing at address with square hip alignment. And so forth.
People are notoriously poor at aiming the putter face accurately at a target. Well over 90 percent of all golfers, pros included, misaim the putter face at address sufficiently poorly that a straight putting stroke would completely miss the hole in the 4-10 foot range. This means that they have a stroke motion that is not straight, but that pushes or pull the putts to compensate for the misaiming of the face. Some teachers basically accept the golfers poor aiming skills and try to match a gating stroke path and ball position in a unique combination for that golfer's misaiming tendencies. I personally don't believe that the misaiming tendencies of golfers in general are that definite and fixed, or that the golfer cannot be taught how to aim accurately, so I consider this an ill-advised bandaid approach to teaching the stroke, with incidental consequences for setup, motion, and putter fitting.
A putter fitting that does not take stock of these features of the body and the person's characteristic postural and movement patterns is not likely to be a very good fitting on a permanent basis.
In conclusion, a good putter fitting session is a lot more than asking you to get "comfortable" to a setup and then measuring the resulting length and lie and handing you a standard grip and loft and head design and weighting scheme at that length and lie. A good putter fitting session also does not simply ask you to make a few putts with different putters until the balls start going in the hole, and then make you a putter with the specs of the successful putter. This approach leaves open the issue of getting you to putt better on a consistent basis. in order to help your putting as much as possible in the fitting process, the fitter needs to know a lot about putting technique and how the human body performs in putting, so that he can spot these issues and know what to do or suggest to resolve them in an optimal way. A clubmaker or retailer who is not also a master putting instructor is not likely to have the expertise needed to get this fitting process finely tuned to the golfer's individual body and movement patterns in a way that promotes longterm sound technique and physics.
For example, there is currently NO putter fitting system on the market that takes into account the gaze direction out of the face. Poor gaze direction produces poor aiming perceptions, and thus poor aim, and thus poor stroke movement. Fitting a putter to someone without taking this into account with some degree of expertise about these consequential effects of gaze will only make permanent the golfer's flaws. You can have all the gee-whiz technology in the world in a putter fitting studio, and it won't do a lick of good for improving or optimizing the golfer's game in the long run without the expertise of a good teacher with sound knowledge of how the body works in sound, consistent, accurate, simple putting with straight aim and a straight roll on the ball out of simple setup posturing and movement biomechanics. This lack of coordination in putter fitting between the physics and the golfer's body and movement patterns should be changing shortly, as the paradigm in golf shifts more away from the deceptive "hard science" of engineering and robotics more towards the performance end of things by fitting the tool to specific human bodies with good technique.
In this connection, I think that technology like the Science and Motion Puttlab, in which the technology focuses attention on how technique and body action produces measurable results at the level of physics, is very helpful in putter fitting. The real "science" here lies NOT in the measurement or data, but in UNDERSTANDING the measurement in terms of the body action and training more effective body action.
Cheers!
Geoff Mangum
Putting Theorist and Instructor
Geoff Mangum's PuttingZone
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