Dear Anders,
To give the short answers first (for those readers not interested in the details):
a) both "face balanced" and "toe hanging" putter designs cause the same problem of toe flaring open by itself (due to poor physics) off the target line AND out of the stroke plane -- I like a "heel-balanced" putter design;
b) typically, under 2 degrees is preferable to 3-4 degrees, on today's smooth, true, tight green surfaces.
c) about 360 grams and up to perhaps 400 to 425 grams is very good for most golfers;
d) aim lines need to be much simpler and more intelligently designed for the visuo-spatial brain processes that support spatial awareness and physical action in relation to targets and space on the greens -- the designs available today are not well informed on visual science.
BALANCING SCHEMES
Face-balanced putters and toe-hanging putters differ only in degree, not in kind. Both designs tend to make the toe flare open in the backstroke, out of the stroke plane, and not simply out of the target plane. The toe-hanging putter has a greater tendency to do this, inherent in the more severe physics of the mass imbalance, but a "face balanced" putter also does this to a lesser degree. This physics reality is CLEARLY not appreciated by golf instructors or players and even by almost all designers, so perhaps they will learn something of great commercial value by looking into these issues with a desire for clarity.
What I really "like" is a "reality balanced" putter, which ends up being a "heel-hanging" putter.
If you take a "toe balanced" putter and position it at the top of your follow-thru and then let it freely swing back to its own top of backstroke position, you will see it swings severely open at the top. That's due to the extra inertial of the extra mass in the toe end of the face: this extra heaviness won't stop as soon as the lighter heel end, so the toe crashes thru the wall of the train station and the toe goes farther than the heel, flaring open out of the target line AND the stroke plane. The "face balanced" putter does the same to a lesser extent. Why is this? Because the center of mass of the putter swinging on a tilt is not the same location as when the putter shaft is balanced on the finger level with the ground to "see what sort of balancing the putter head has". Finger balancing and the balancing during the swing are simply not the same, and what you want to know about is swinging or so-called "reality" balance -- what are the balance physics and inertial effects during a stroke, not when the putter shaft is poised on your finger.
But if you invert a "toe-balanced" putter (flip it heel-away, toe-near, underside of grip now on top) and suspend it at the top of the follow-thru and then let it swing to it's natural position at the top of the backstroke, you should see a putter that NOW swings squarely back and thru, sans unhelpful "toe-flow" causing the putter to open out of plane and off line. Interesting, huh?
To see the differences, visit these short movies at Positive Putters. Out of the nearly 600 current putter manufacturers, fewer than ten utilize these balancing principles in their designs (and none of the so-called "top" designers use anything other than the balance schemes that cause problems).
If you have a toe-flaring putter design, and don't like having to correct the putter face when it flares out of the target line AND out of the stroke plane (and that includes 99.9% of all golfers today), then you probably would like to know what is required to "prevent" the inherent physics from doing damage. All that is required is managing the extra mass, which is on the same order as about one fourth of a golf ball or less for the extra mass out of the proper balance towards the toe / away from the heel. Handling this requires a very modest increase in grip pressure, so there is a MINIMUM grip pressure to use every stroke, otherwise you are allowing the bad physics its head to mess with your stroke and cause unnecessary problems that need fixing. Golfers who think "feel is in the fingers and the less grip pressure the better" don't seem to know what is actually happening in the stroke, so again it's a case of the tail wagging the dog. These golfers are putting unmindfully in reaction to unhelpful physics, and this in effect trains these golfers non-consciously how to manipulate the putter to get some sort of success. That's fine, but skill without knowledge equals streakiness, with fall-offs from performance without the know-how for immediate self-correction. These fall-offs can last months or years. Ask Mike Weir (4 years) or KJ Choi (5 years) or Joe Durant (15 years), who all experienced great ghastly gaps between stellar putting rounds without the slightest clue how to fix the problem.
LOFT
The guiding principle is: the least loft required by the usual surface speeds and conditions you play is best. On today's greens (vastly improved since 1980 over the past), that is around 0-2 degrees, and 3-4 degrees is too much loft. Players using putters with too much loft unmindfully tend to change their strokes to overcome the adverse effect, by delofting the putter at address and dragging the putter low and level thru the impact area and similar idiosyncratic dynamics. That is the tail (putter design) wagging the dog (golfer's stroke). Good luck to that dog becoming a masterful "wagger" of his tail.
WEIGHTING
The overall weight and its effect on the overall center of mass of the golfers arms, hands, and putter as a unit is more important than swingweight, and the overall weight should be matched to the golfer's body and strength and stroke timing primarily and also to the typical greens and conditions played. In general, heavier putter heads promote more inertial stability in the stroke, making it less likely that the fidgety golfer will adversely alter stroke path (the threshold force required to change the stroke path of a heavier putter is higher and so more forgiving of little fidgets.) But there is a range, and simply heavier and heavier is stupid. About 360-370 grams in the putter head is approximately "normal" for most guys, and 450 grams is just "too danged heavy", resulting in too-tight grips and poor muscle patterns and biomechanics activating the backstroke (snatching the putter head back off the ground, usually across the target line resulting in a loopy stroke path). Also, the center of mass of the system should probably be closer in to the body than typical with conventional putter designs, as this makes the golfer less "handsy" in the action and more consistent and accurate for line and touch.
Incidentally, contrary to current "old wives tales", a lighter putter is not better for a faster green. A lighter putter results in the need for more velocity and force at impact compared to the usual weight, and this in turn generates either a change in the golfer's timing or a LARGER stroke than usual and in any event a faster stroke. The implicit notion seems to be "lighter is more sensitive, and slicker greens need more sensitivity for distance control". That's a bit confused. The "usual" heavier putter does very very well on fast greens (think Augusta National) and the myth of requiring extra "sensitivity" or even "less blunder-bussing" to control distance is simply a fear-induced fantasy. It's similar to believing in the boogey-man lurking in the dark woods just outside your family's yard -- understandable but not particularly rational, since you've never really seen the boogey-man in person. So take a look!
If you putt with a light putter and a regular not-light putter at Augusta National, this is the effect for the same 20-foot downhill putt: A) the light putter has a larger-faster stroke that results in FORCE 10.102 whereas the usual not-light putter has a shorter-slower stroke that results in exactly the same FORCE 10.102; or B) the lighter putter is swung with a shorter-even-faster stroke to generate FORCE 10.102 while the usual not-light putter requires nothing out of the habitual ordinary. In any case, the 20-foot downhill putt requires FORCE 10.102 and none other for optimal results. In addition, the lighter putter is easier to fidget out of square due to less inertial stability than the usual putter.
Similarly, changing the weight on a putter head in an attempt to "regulate" (not attain) an accurate sense of touch for different surface speeds is just not the right approach. Some golfers (including very prominent golfers on Tour) fiddle around with the lead tape on their putters in an effort to "regulate" different greens to their stroke habits, instead of just accepting the differences. Typically, these golfers note exactly what SIZE backstroke makes a 10-foot putt for touch on a Stimp 11 green, and then when they migrate to a Stimp 9 or 10 green, they "fiddle around" with more tape until the SIZE of their 10-foot stroke on the slower green is EXACTLY the same as it was on the Stimp 11 green. This whole enterprise is AGAINST paying attention to the reality of the green and to the natural timing and movement pattern that takes its cue from the reality of the green speed. This CAN'T be good for the golfer over the long haul.
AIM LINES
Aim lines are being designed out of vast clouds of ignorance about visual processing for spatial awareness and physical action, and practically all designs are frankly goofy. Optometrists and amateurs and veteran designers all get some small "notion" of what is "best" and then are off to the races trying to justify what they have come up with, but no one seems to have good common sense or any reasonable fund of neuroscience about how the brain uses vision for body action in space.
No putter manufacturer that I have ever heard of designs aim line(s) and then markets the proof that the design helps golfers aim better so that at the end of the process the laser shows that the golfer positioned the putter face exactly where intended some substantial distance off to the side, AND the golfer knew that before the laser was activated, AND this aim also works well with the stroke that the golfer habitually produces so that the putts ALSO go where the putter face aims, AND this aim line design is equally effective for a wide range of golfers. Such proof would probably strongly imply that the designer actually understood / knew how the aiming process works in the brain and what is important and what is not.
This great silence on the matter of scientific proof of the efficacy of manufacturer's efforts to design good aim lines is all the proof I need to conclude that none of them have the least idea what they are trying to get accomplished or how to do it. For example, most companies offer several choices about the aim lines in their various models: Does that make sense, if one is better for human visual processes than another? If instead the notion is that "whatever works for you is best" guides the design process, what do you suppose the designers are doing when they offer the world of 40 million individual worldwide golfers three or four patterns to pick from?
Frankly, golf equipment manufacturers, designers, optometrists (Nike hires one to help design putters), and dilletante wanna-be putter designers should probably either learn something about how the brain works in aiming, do a little testing, or "take up bowling." The one thing they won't stop is the marketing hype to accompany whatever they have managed to come up with for aim line(s). Without getting too deep into the science, suffice it to say that marks (not necessarily "lines") to help with aiming need to be vastly simpler and more intelligently designed for spatio-visual processing in conjunction with physical action than heretofore.
David Edel (www.edelgolf.com) stands alone among putter designers today in actually INVESTIGATING this issue, along with help from the empirical testing and experiments ("studies") carried out by David Orr at Campbell University's Professional Golf Management program (www.orrgolf.com). (Incidentally, his data "sample sizes" shame those of other golf "scientists" as well as probably all sports science studies for putting in academia.)
David Edel putter fitting session
David Orr presenting findings of his studies at MIT golf technology conference
According to my understanding, Edel and Orr have been learning that the aim line in isolation is not what determines accuracy of aiming or lack thereof, and that the total features of the putter design all make separate contributions, such as the shape of the putter head, the appearance of the shaft as angled into the head, the hosel design, the prominence of features in the interior appearance of the putter head, and many other contributing factors. And this is BEFORE taking stock of the golfer's personal biases for vision and stroke action, which also affect the aiming process. The general thrust of the investigation is to find understanding for practical application of WHY one putter design pattern would work better than another with a specific golfer's set of biases, resulting in a science-driven, principled, knowing way to "fit" putter designs to golfers, including optimizing the aiming process by an integrated approach to the golfer AND the tool.
This effort parallels and complements my own researches into what actually happens in the body, vision, and brain when a golfer looks at a putter and aims it. Hopefully, our parallel efforts are converging and mutually supporting and informing, as they appear to be so far. The final word, I suggest, is that aiming putters is at the beginning of its first-ever serious learning curve.
OTHER DESIGN FEATURES
Numerous other design features (your "etc.") promise the world and deliver anthills, as usual. Using real "investigative" science, not the dumbed-down "ranking / sorting" science usual in sports science academia or the "to measure is to know" delusional science of most golf technologies, engineers and club designers Werner and Grieg tested isolated design features of putters against a simple criterion: does the feature help the golfer have fewer strokes per round, and if so, what is the magnitude of the effect? (See their book for detailed data and testing protocols: How Golf Clubs Really Work and How to Optimize Their Designs).
Their studies concluded that, yes, all design features make a difference, but the magnitude is so miniscule compared to the golfer"s basic variability for reading, aiming, stroking, and controlling distance, that the effective helpfulness of the design features were all "swamped" by the larger variability golfers have in their skill (this includes pros). The design effect versus the need to control variability is typically on the order of 1 to 10 or 1 to 20, with the design feature helping only 10% of the need while the golfer is coming and going another 4 to 10 times that much left or right, long or short, etc. For example, a so-called "better" MOI design does not necessarily help a bad golfer get better, and a bad golfer may well do better using a "poorer" MOI design for any number of reasons. The helpfulness of the "better" MOI design might reduce distance control errors by perhaps 4 inches on a ten or twenty foot putt but the golfer cannot consistently benefit from this because he is off distance by plus or minus 4 FEET (48 inches) over 90 percent of the time. This same "swamping" of design benefit runs thru all the designs about equally. None of them matter enough to get excited about, in comparison to what the golfer can accomplish for improvement simply honing his skills at reading, aiming, stroking, and controlling distance. There are no magic bullets, so golfers need to have a good cry, grow up, and learn how to putt without constantly chasing design fads.
Frank Thomas, regarded by quite a few as a scientist -- he's fond of declaiming "To measure is to know", said in a radio interview with respect to his personal offering of a putter design (which, incidentally, has nothing interesting for aiming): "I wracked my brain for a long time trying to come up with something innovative for my Frankly Frog putter design, and all I could come up with was the color green." (Edwin Watts Better Golf Podcast with co-guest Scotty Cameron and host interviewer Fred Greene). This is quite at odds with his public marketing that states his putter is the most scientifically advanced putter on the market.
So the message is: Marketing statements are not science, and may not even be truthful, and may even be deliberate misstatements of the true belief. Golfers should take this state of affairs as the "school for skepticism" that it is.
Cheers!
Geoff Mangum
Putting Coach and Theorist
Geoff Mangum's
PuttingZone
PuttingZone Clinics
Flatstick Forum
PuttingZone Channel on YouTube
PuttingZone Picasweb Image Gallery
Golf's most advanced and comprehensive putting instruction -- you're either in the PuttingZone, or not. Over 2.5 million visits -- 100,000 monthly from 50+ countries -- and growing strong.