Dear RFT and Jay,
Strictly speaking, the "fluidity" of the stroke does not have a lot "directly" to do with the weight of the putter or the putter head. Clearly, there is a relationship, but let's discuss the body first, and then the body with a putter second.
Without a putter in your hands but adopting your usual putting posture at address, your hands meet in some fashion near your lap. If you move as you do in your normal putting stroke, do you make a "smooth" stroke going back? Do you then make a "smooth" stroke coming forward? if you do, then nothing really needs to change when you place a putter in your hands, even if the putter is ultra-lightweight, so long as the putter is not grossly too heavy for you.
In other words, if the question is the smoothness or fluidity of the stroke, the underlying reality that needs dealing with is in the body, first and foremost. The factor of the putter's weight can only be appreciated aright once you have a good understanding of the basic problem your body might have in making a smooth stroke.
If there is a difference between the motion you make without a putter and the motion you make with a putter, the usual culprit seems to be what changes in the golfer's mind about what he is doing in the motion. Without a putter, the golfer just moves his shoulders, arms and hands as a nice unit. His sense of the body from center outward ceases at the limit or boundary of the hands. He may think about moving the hands from here to there and back again, or he may not especially be aware of his hands and simply makes a motion of the whole assemblage. But when the putter is also in the hand, the boundary of the self is extended outward beyond the hands to the end of the stick -- i.e., the putter head. If the golfer tries to be aware of moving the putter head smoothly, instead of moving his body smoothly, he gets a problem. The sense of the putter head involves a sense of mass at the end of a stick that is usually significantly greater compared to the golfer's sense of the mass or weight of his hands.
To get a read on this difference, suspend one hand, gain an awareness of the hand as a separate part, and then move the hand back as in a backstroke, paying attention to whether there is a sense of dragging it away from its starting place. Then hold a putter in this same hand, suspend the arm with the putter head not on the ground, and make a backstroke, assessing what sort of tug effort is involved in this motion.
While the difference might not seem like much, this is not how the brain gauges the difference. First, the brain knows that the putter head is very much further out away from the body than the hand is. The torque required to move the mass gets greater the farther out from the moving hinge. (In this case, we assume the hinge is the shoulder.)
Torque is Force x Lever Arm, and the putter head is at least twice as far away as the hand ("lever arm" is twice as long from hinge to mass), so twice the force is needed to move the same mass.
Anthropometry measurements say that the human hand is typically 0.6% of body mass, so a 150 pound man probably has a hand mass of about 0.9 pounds. In grams, this is about 400 grams (16 ounces per pound in 0.9 pounds is 14.4 ounces, and 28.4 grams per ounce makes this 408 grams). Putter heads are typically 350-375 grams, so there is not a great difference in mass. So the relationship between the torque for moving the putter head versus moving the hand is nearly 2 to 1 -- twice as much "tug effort." Golfers personally may not be consciously aware of this, but the brain certainly is.
The effect of this difference in the brain and mind of the golfer (whether at a conscious level or a subconscious level) is to draw attention to the putter head as a mass, so that the brain treats moving the putter head like a problem rather than something routinely done all the time in an effortless / problem-less manner. This "problem on the doorstep" state of mind right before pulling the trigger to initiate the motion vest the brain's conscious or subconscious awareness in the putter head as a mass somewhat far from the shoulder. This encourages the brain to use muscles CLOSER to the putter head, and that means the brain has a built-in bias to "move the hands to move the putter head", rather than to "move the shoulder to move the putter head".
This has always been the case, and will continue to be the case. A good shoulder stroke is learned and executed despite this bias. "Dead hands" may be natural when moving the hands about in the air without a putter, bit when the hands are holding a putter, a "dead hands" stroke is not natural, even though it is superior.
Why would a "dead hands" stroke be superior to a "move the hands to move the putter head" stroke? The reason is basically biomechanical. In order to "move the hand", the brain uses a joint that is closer in to the center of the body than the part being moved (more "proximal" as the good folks learn in college how to jargon-up the plain issue so it looks more "scientific" and difficult). The joints to choose from are, in order, the wrists, the elbows, the shoulders, the upper torso as a whole. The usual movement of the hands by the wrists is only a "flapping" action that does not traverse sufficient space, and so gets disqualified for any reasonably ample putting stroke. The joint of choice then becomes the elbow. In order to smack yourself in the face, you "move your hand with your elbow", not your wrist, and not your shoulder. The elbows are biomechanically engineered to open and close in only one direction (closing: hand up at shoulder socket; opening: hand away from shoulder socket to the point where the arm is straight and no further). The elbow opens and closes in an opposite way to the knee (closing: heel up to hip; opening: heel away from hip until leg straightens).
If you "use your elbow to move the hand to tug the putter head back from its static position at address," you MUST flex the muscles on either side of the elbow that closes the elbow. This closing of the elbow by use of these muscles typically a) directs the putter head out beyond or across the line of the putt, setting up a "loop" in the stroke that requires manipulation in some fashion to deal with, and b) creates a dis-coordination of motion between the shoulders and upper arms that at least complicates learning the feel of the movement and repeating the feel consistently, since it differs in degree with larger strokes versus smaller strokes. This is why Loren Robert's tip to start the backstroke with the lead shoulder shoving the putter head back is a really, really good one. If you want a smooth stroke, don't use the muscles of the forearm and upper arm on either side of the elbow joint to tug the putter head mass back from its resting place as a way to initiate and carry out the backstroke motion -- instead, start the putter back by dipping the lead shoulder to shove the shaft and putter back at tyhe start.
So, allowing the putter head weight to draw attention to itself in the brain is not really a good thing.
Why do golfers always yammer on so about swingweight? "Swingweight" is a made-up ratio that essentially asks "how fat is the diver at the end of the diving board and therefore how much does he bend the diving board given the length of the board"? It's all about the corpulence of the diver (putter head), when it shouldn't be.
In the full swing, "swingweight" may mean something because golfers believe it helps TIME the stroke back and thru. What is really going on is that golfers don't want to have different swingweights for different full-swing clubs. But there's usually only one putter. Why would golfers worry about and vest belief in the specialness and criticality of swingweight in a putter?
These golfers don't want to get away from "moving the hands to move the putter head." They like it. I suggest they simply don't know much about the alternative, which is focusing on the real source of smoothness and consistency in the body, not focusing on the "problem at the doorstep" of "moving the hands to move the putter head." Moving the putter with the torso as a whole is a LOT smoother than "moving the hands to move the putter head."
NOW, on to the second issue: What effect does putter weight have when you learn to like a "dead hands" stroke that uses the torso as a whole to move the putter head? The main effect is when the weight of the putter gets too much. Then the initiation of the stroke exceeds a good steady grip pressure, as this usually confy tonic setup "form" that unifies hands, arms, and shoulders into a unit is not sufficient to transmit the required force needed to heft the putter head back from its static address position. In other words, there is a point in increasing putter head mass where starting the stroke with a modest grip pressure just won't do the job, and EXTRA grip pressure (aka tension) is required. Then we're right back in the swamp of "moving the hand to move the putter head."
So, strictly speaking, there is no problem in the smoothness and fluidity of the stroke with the "lightness" of the putter, and the real problem crops up when the putter weight draws attention to itself or forces changes in the hands at the start of the stroke.
This is not to say that putter weight cannot be optimized to a specific golfer. Clearly, most golfers aren't well trained about these issues in physics, biomechanics, and neuroscience. So they are "bothered" by putters that are too light to them or too heavy to them, and golf culture promotes the belief in this made-up thing called "swingweight" so golfers follow the herd.
What to do about these guys? First, treat the mind by training with an ultra-lightweight putter until you REALLY get handle on what makes a stroke smooth or jery. Then, second, just in case you can't wrap your head around that, fiddle with swingweight and overall putter weight until it's not calling attention to itself.
I believe it is exactly backwards to want to "feel" the putter head with "lag" inertia at the start, lag "continuance" at the top of the backstroke, "lag" inertia at the start of the downstroke, and "release" of the putter head thru impact, and ALL that focus on the putter head. The body motion needs to be the focus.
So let's fiddle with the weight. If you want to "restore" swingweight to its former status before cutting a putter down, there is a
Swingweight Calculator to use. Input the distance from the balance point back to the top of the club and the total weight of the club and hit "calculate." If you do this for the original measurements, and then compare the calculation for a club with the new distance after cutting, you will see a big drop in swingweight. For example, a balance point to top measurement of 25 inches for a 19.7 ounce club compared to a 24 inch measurement and a 19.6 ounce club moves the swingweight from D2 to C0. There are 13 sweighweight points between D2 and C0 (to D1, D0, C10, C9, C8, C7, C6, C5, C4, C3, C2, C1, C0). To move the C0 back up to D2 takes a heck of a lot of lead tape. "For that purpose, one 4-inch-long strip of half-inch wide lead tape will increase the swingweight of any club by one point." You would need 13 such strips to move the C1 back up to D2.
In general, overall weight is more important than swingweight, especially for putters. (
See this article.)
Putter shafts are somewhere around 120 grams and up, and putter heads are typically in the range of 350 grams, and the grip might weigh 60 to 80 grams, so a ballpark overall weight is around 530 to 550 grams. When you cut down a shaft by an inch, you don't lose much mass (it's a hollow tube). So to keep the same "overall" weight is not that tough.
To get the putter back to the same overall weight, add the same lead tape mass that got removed in shaft mass. Roughly speaking, 1 inch of a 30-inch shaft is 1/30th of the mass, or 120 grams / 30, or 4 grams per inch of shaft cut off. Adding 4-5 grams per inch cut off putts the shaft mass back and restores the overall weight to what it was before cutting. Or get a more massive putter head. Or add salt or powder down inside the shaft. Or get a heavier grip. Or use a back weight in the top of the shaft.
Now let's address what is a "good" overall weight. This really depends on the golfer's body, his stroke technique, and the greens he usually plays. Consider an average adult male using a conventional putter and stroke technique. He is about 5'10" tall, weighs above 150 pounds, and uses a 35-inch putter in the standard sort of stroke. Here are some
Human Anthropometric ratios of body mass to limb segment:
Segment = Hand
Definition = Wrist / knuckle II digit 3
Segment Weight ÷ Total Body Weight = 0.006
Centre of Mass ÷ Segment length, Proximal = 0.506
Centre of Mass ÷ Segment length, Distal = 0.494
Radius of Gyration ÷ Segment length, C of G = 0.297
Radius of Gyration ÷ Segment length, Proximal = 0.587
Radius of Gyration ÷ Segment length, Distal = 0.577
Segment = Forearm
Definition = Elbow / ulnar styloid
Segment Weight ÷ Total Body Weight = 0.016
Centre of Mass ÷ Segment length, Proximal = 0.430
Centre of Mass ÷ Segment length, Distal = 0.570
Radius of Gyration ÷ Segment length, C of G = 0.303
Radius of Gyration ÷ Segment length, Proximal = 0.526
Radius of Gyration ÷ Segment length, Distal = 0.647
Segment = Upper arm
Definition = G.H jt / elbow
Segment Weight ÷ Total Body Weight = 0.028
Centre of Mass ÷ Segment length, Proximal = 0.436
Centre of Mass ÷ Segment length, Distal = 0.564
Radius of Gyration ÷ Segment length, C of G = 0.322
Radius of Gyration ÷ Segment length, Proximal = 0.542
Radius of Gyration ÷ Segment length, Distal = 0.645
Segment = F'arm+hand
Definition = Elbow / ulnar styloid
Segment Weight ÷ Total Body Weight = 0.022
Centre of Mass ÷ Segment length, Proximal = 0.682
Centre of Mass ÷ Segment length, Distal = 0.318
Radius of Gyration ÷ Segment length, C of G = 0.468
Radius of Gyration ÷ Segment length, Proximal = 0.827
Radius of Gyration ÷ Segment length, Distal = 0.565
Segment = Upper limb
Definition = G.H jt / ulnar styloid
Segment Weight ÷ Total Body Weight = 0.050
Centre of Mass ÷ Segment length, Proximal = 0.530
Centre of Mass ÷ Segment length, Distal = 0.470
Radius of Gyration ÷ Segment length, C of G = 0.368
Radius of Gyration ÷ Segment length, Proximal = 0.645
Radius of Gyration ÷ Segment length, Distal = 0.596
Roughly, the "arm" from shoulder to fingertip is about 5% of the body mass, and for a 150-pound person that is 7.5 pounds for each arm, or 14 pounds for both. In grams, 14 pounds is 6,816 grams (6.8 kg) -- 12 times more massive than the putter itself at 575 grams.
What you want out of total putter weight is something to help suspend the arms and hands in a "dead hands" muscle calm and then help KEEP THEM SUSPENDED with steady tonic form during the stroke. As above, the main culprit is usually the muscles around the elbow changing the forearm in relation to the upper arm. So let's look more closely at that.
The upper arm is 0.028 x body mass while the forearm plus hand is less massive, at 0.022 (a difference of 0.006 or about 20% of 0.028 or one-fifth less massive). What would it feel like if the forearm plus hand were EQUALLY massive as the upper arm? Add 0.6% of your body mass to the forearm-hand and see. In the case of a 150-pound person this is 0.9 pounds. That is roughly one extra hand on each arm. I don't think it advisable to go much above this general range.
For illustration, we are talking roughly about the added weight of holding a tennis shoe or something similar, perhaps a full standard-size jar of creamy peanut butter.
So this range of 0 to 0.9 pounds is what we want to consider for adjusting total putter weight (0 to 408 grams). Since humans aren't usually able to tell the difference between two weights unbless the difference exceeds 10% (the so-called "Just Noticeable Difference" or JND from human psychometrics), the size of "chunks" to add or substract from total putter weight need to come in these 10% increments. Starting with a total putter weight of 500-gram, one could add 50 grams at a time and assess each step up to see if it helped calm down the elbow-activating muscles. There are probably only 3-4 steps to consider in this process, as after that you will be changing your grip pressure in response to a too-heavy putter. Where exactly any individual falls in this process depends on a number of factors, including their specific body characteristics, their strength, their sensitivity, their setup postures, their stroke movements, and then the sorts of greens they usually play.
Cheers!
Geoff Mangum
Putting Coach and Theorist
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