Dear Donald,
Thanks ... a simple little question like this should only take a few ... YEARS to answer!
Seriously, it's important at the beginning to state the issues in the right order or we'll get lost pretty quickly.
First, what is topspin?
Second, what generates topspin?
Third, what does it do to help putting?
Fourth, is the trouble to get topspin worth the effort?
Your exact question is: "Do certain putters produce topspin as claimed?" Assuming a putter company claims that its putter "produces topspin," and this is taken to mean that every golfer using the putter on normal greens with the stroke that normal golfers all use will see the ball roll with topspin every stroke, the answer is fairly obvious. No matter what you mean by "topspin," the answer is "no" for several reasons. But first, "what is topspin."
"Topspin" is the rolling of the ball top-forward / bottom-backward in the direction of motion of the ball. In contrast, "backspin" is the rolling of the ball top-backward / bottom-forward in the direction of the motion of the ball. Also in contrast, "skid" is the mis-match between the rolling direction and speed of the ball and the lateral or translation direction and speed of the ball. Each of these sorts of ball movement come in changing degrees. Topspin and backspin are mutally exclusive -- it's one or the other, never a mixture. But "skid" can be mixed with either "backspin", "no spin", or "topspin", and this mixture changes as the putt progresses.
A typical putt starts with some airborne launching of the ball off the ground with "backspin", then the ball lands on the grass and the lateral speed and direction of the ball (at the bottom of the ball) meets the stationary grass surface -- so the ball at this time has two sorts of motion -- sideways across the ground (translational or lateral speed and direction) and "backspin." When the stationary grass surface conflicts with the bottom of the moving ball, the "friction" between the grass and the ball's bottom starts reducing "backspin" in favor of top-forward / bottom-backward rolling. This transition when there is some skidding and some backspin lasts for a certain time and length of the putt that depends on the grass friction and how fast the ball is moving laterally when it meets the ground. The friction of the grass on the bottom of the ball is fairly steady and even, so the transition is pretty smooth and even, too -- the "backspin" dies out and the ball begin to have less and less backspin, and then at some point there is "no spin" of the ball as it moves sideways across the ground. But there is still skidding, as there is still a mis-match between the sideways speed and direction of the ball and the (non-)rolling direction and speed of the ball ("no spin" doesn't match the sliding speed). From this point forward, the constant friction shoving the bottom of the ball backward starts to make the ball spin in the top-forward direction more and more, so there is now a mixture of skid and topspin. As the movement continues, the topspin increases fairly smoothly and evenly. As the forward rolling increases, the rolling of the ball starts to catch up to the sideways speed of the ball, and this reduces the skidding. Finally, the forward rolling of the ball keeps up with the sideways speed and there is no more skidding, and only forward rolling. Throughout this whole starting phase (called the "skid phase") of a typical putt, the sideways velocity (speed and direction) of the ball is slowing down from its initial velocity right after impact.
So, during the skid phase, the separate stages of the skid phase are a) "mixture of backspin and skidding in which the backspin is declining and the skidding difference between the ground and the bottom of the ball declining", followed by b) a brief instant when there is "some skidding and no backspin or forward spin", followed by c) a period when there is increasing forward spin and the skidding difference between the bottom of the ball and the forward rolling declines all the way to no skidding and only roll. Once there is no more skidding, the skid phase is over, and a "rolling only" phase occurs while the ball continues to slow down from "rolling friction", which is right much less powerful in opposing the ball than "sliding friction", but still enough to keep slowing the ball down until it stops. During the "skid phase", the "brakes" on the sideways movement of the ball are being applied more forcefully than the comparatively easier braking that occurs during the "rolling only" phase.
The "skid phase" of the putt requires different lengths depending upon the initial velocity of the ball and the grass friction (a "fast" green with less friction has a lengthier skid phase because less friction takes longer to rid the ball of backspin and get the ball's forward spin up to speed). So, probably contrary to most people's notion, a putt across a "slow" green skids "less" (that is, for a shorter total length across the green) than the identical putt would skid on a "fast" green. But in every case, regardless of the grass friction, the rolling speed of the ball matches the sideways speed of the ball at that point in the putt when the initial sideways velocity right after impact and the ball's contact with the surface (call it X miles per hour or feet per second) has declined by the grass friction to 5/7th the initial velocity. So if you hit a putt that starts off at 7 feet per second, and then the skidding starts, once the friction has slowed the ball's sideways speed to (7 times 5/7th or) 5 feet per second, the skidding will be over with and only forward rolling will remain for the rest of the putt. Typically, the length of a putt required for this point in the ball's sideway velocity to slow that much is about 15% of the total length of the putt. So on a typical 10-foot putt, the skid will be over by about 1.5 feet. There is a little difference in the total length of the skid phase, depending on how fast the putt starts out, with mild putts having a proportionately shorter skid phase than putts hit harder / faster. (See
CB Daish, The Physics of Ball Games, PuttingZone Research 5.01.09.05.)
In physics, the "roll" of a ball requires one circumference of the ball, and that is 5.28 inches. If you wrapped a string around the circumference of a golf ball 1.68 inches in diameter, the length of the string would be 5.28 inches. If you laid the string straight out on the grass, this is how far a golf ball "rolls" in one "spin" when there is no skidding. If you marked the ball with one dot and set the dot on the grass at the bottom of the ball and rolled the ball across the grass one spin or one revolution until the dot was again on the bottom of the ball, this "roll" would cover 5.28 inches sideways across the grass (about one hand's length). This combination of sideways movement and rolling corresponds to no skid and all forward roll. This is after the skid phase has concluded. During this "no skid, all roll" partt of the putt, the ball covers 5.28 inches sideways every time it rolls forward once, and there is no mis-match between sideways velocity and rolling velocity. There is thus no "sliding friction" even though there is still its milder cousin "rolling friction."
If you set the dot on the bottom and "slid" the ball 5.28 inches without any rolling at all, so the dot stays at the bottom, this is movement of the ball that corresponds to all skid and no spin. This is only a single instant in the transitioning of the ball's movement from backspin to forward spin.
If you set the dot on the bottom and then slid the ball sideways while also rolling the ball backward, this corresponds to "a mixture of sideways skid and backspin."
All during the skid phase, the mis-match between the sideways velocity of the ball and the rolling of the bottom of the ball is declining. So the powerful "sliding friction" is also declining in power/ But while the mis-match is at its greatest, the friction on the bottom of the ball is also greatest, so the mis-match is going away quickest at the earliest part of the skid phase. The more the ball slows towards the 5/7th point, the less the mis-match and the less the sliding friction.
Throughout this whole time, there is an assumption that the backspin on the ball is ALL backspin and no side spin. That is, the backward rolling of the top and bottom of the ball take place in a single plane, and this plane meets the surface perpendicularly and is aligned the same direction as the ball moves across the green. There is NO tilt in the backspinning of the ball. If there is any tilt to begin with, the sideways sliding across the surface will get rid of it pretty quickly and ALL rolling of the ball will thereafter be in a plane that is perpendicular to the plane of the surface and this vertical plane of rolling will match the sideways direction of the ball's travel across the green. There is no sliding friction athwart the rolling direction of the ball.
What are typical rates of backspin? Something on the order of 0.5 revolution per second of backspin (not much) at launch to 2-3 revolutions per second of backspin at launch (a fair amount, and typical for most putter designs). This backspin rate can be expressed as a percentage of the initial sideways velocity of the ball. One revolution per second (rps) is the same as 5.28 inches per second (ips). If the putt starts off at 7 FEET per second (fps), this is the same as 84 inches per second (ips). As a percentage, 1 rps) in a 7 fps at start putt is 5.28/84, which is 6 percent. If a putter design imparts a 6% backspin for a given sort of stroke, it will pretty much always impart 6% backspin no matter how slow or fast the ball is hit at the beginning. In comparison, a putter that imparts only 0.5 rps at impact on a 7 fps blow is half the other putter, or 3%. Putter designs usually fall somewhere in the 3% (good) to 10% (not so good) range.
Second, what generates "top spin"?
According to studies by Dr Norman Lindsay, the relative locations of the impact point on the face of the putter and the putter head's center of gravity is the main determinant of the putter's backspin percentage. In particular, an impact point high on the face when the putter head COG is low and slightly recessed back from the face is the best for reducing backspin. This combination, he says, produces a "vertical gear effect" in which the lighter top of the putter head shears across the top of the ball faster than the heavier bottom half of the putter head, imparting forward roll. Depending upon how much loft is designed into the putter face and how the stroke delivers the putter face with "dynamic loft" at impact, this vertical gear effect can reduce backspin and may even eliminate backspin entirely and generate top spin at the beginning of the putt, so the ball meets the ground with less or no backspin and possibly with some degree of forward spin. In his studies, for example, the C-Groove putter imparted 1% FORWARD spin when the impact point was high on the face, compared to 2% BACK spin when the ball was impacted low on the face, given the putter's design COG and loft. For an identical delivery of the Odyssey Two-ball putter with impact high on the face, the putter imparted 3% BACK spin at launch, and whn impact was low on the face, the putter imparted 10% BACK spin. (See
Lindsay Putters, Measurements.
Here are the design factors in different putters that Dr Lindsay says explain the difference:
WHAT GIVES TOPSPIN?
Vertical gear effect
ItŐs well known that hitting the ball off the heel or toe of a driver puts sidespin on the ball, even if the clubface is square at impact. The same happens with a putter. WhatŐs less well known is that vertical spin changes with impacts above or below the sweet spot. Hits above the sweet spot (on a putter) give topspin. Hits below the sweet spot give backspin.
Low centre of gravity
The sweet spot must be low to ensure vertical gear effect works to give topspin. In most putters the CG is not low enough to place the sweet spot below the centre of the striking face. Lindsay putter-heads have exceptionally low CG with the sweet spot well below centre. For hits at or near the centre, topspin compensates for linear ball velocity changes, giving superb putt length consistency.
Deep centre of gravity
Gear effect is proportional to the depth of the CG behind the putter face. For good topspin you need the putter-head CG positioned from half to two inches behind the face.
Low minimum inertia
Low minimum inertia (front-back weighting) assists vertical gear effect, giving higher topspin. At the same time itŐs important to have high heel-toe weighting (i.e. high maximum inertia).
Variable face loft
Gradual loft reduction (face roll) can be used on the bottom of the putter-face to introduce a small amount of negative loft. This generates topspin by oblique impact, even though the ball is hit on the upswing on this part of the putter-face. This arrangement is especially beneficial for length control on long putts.
Centred shaft axis
LindsayŐs recent pioneering research into putter impact has revealed a major problem - the position of the shaft axis is critical for vertical gear effect. Aligning the shaft axis with the putter-head CG ensures the best performance for topspin and feel.
Lindsay putters
Lindsay putters combine all the above features in Patent Pending designs creating the worldŐs first ALL-TOPSPIN PUTTERS.
WHAT GIVES BACKSPIN?
High centre of gravity
With high CG the ball is usually hit below the sweet spot. Backspin increases and ball velocity reduces as the impact point gets lower on the putter-face. These effects combine to give poor length control, and this can get really bad if the CG is both high and deep.
Face loft
Some loft is necessary to lift the ball at impact, particularly on slow greens. But loft generates backspin and raises the sweet spot, so choose a putter with the minimum loft that suits you. As well as imparting topspin, vertical gear effect lifts the ball slightly so less loft is required.
Offset neck and hosel
Offset hosels on long neck extensions joined to the front flange are a very common feature in putters. This design increases minimum inertia and raises the effective sweet spot, making backspin more likely.
(See
Lindsay Putters, Topspin.
Aside from the design features, Lindsay says that the degree of backspin / forward spin is partly up to the golfer in how he delivers his putter head to the back of the ball. Keeping the putter head low and reducing the upward trajectory of the blow, while delivering the putter face so that impact with the ball occurs high on the face, all help reduce backspin.
There is another view of the matter in those believing that a HIGH center of gravity design in the putter head reduces backspin and/or promotes top spin. The studies that support these claims may have different conditions than those used by Dr Lindsay, so it is difficult to say whether one view is correct and the other incorrect. It could be that the exact way the testing was done includes different ways of delivering the putter head thru the ball (which amounts to the "human factor" in using the putter, as opposed to the "design physics" inherent in the putter regardless of the huma's particular way of using it). A completely different explanation for the different test results is the possibility that there is MORE THAN ONE WAY in the design physics to impart less backspin and more top spin. Who knows for sure? I don't think the science has definitively resolved this issue.
Third, what does it do to help putting?
By this issue, I mean: What does reducing backspin / promoting top spin at the very beginning of a putt matter to the success or failure of the putt?
Every putt gets past the skid phase into "rolling only" before it sinks or misses (unless you hit a putt so fast so close to a cup that the ball is still skidding when it goes in, or jumps over the cup). So what this issue asks is: during the initial 15% or so of a putt, what difference does less backspin / more top spin make to the putt?
The difference comes in either line or distance. In terms of DISTANCE, more backspin results in greater "sliding friction" at the beginning compared to a putt's skid phase that starts with less backspin. This means the more-backspin putt loses more energy than the less-backspin putt during their skid phases. The numbers Dr Lindsay finds is that the Odyssey Two-ball putter results in putts that lose about 34% of their total energy in the skid phase, whereas the C-Groove loses only about 20% of its energy during the skid phase. So the DIFFERENCE in energy, at least, is usually around 15% from the design features alone. The more-backspin design will send a ball perhaps 1.5 feet shorter when an identical force blow of a less-backspin design would send the ball 10 feet.
In terms of LINE, the issue is pretty clouded, as Yoda might say. Lots and lots of folks "say" that "it stands to reason" or "it is common sense" that a "ball with top spin" will "hug the line" or "hunt the hole" but what exactly is the case? Remember, we are only discussing the skid phase differences -- after that, all balls roll the same. So there is no such thing as a ball "hunting the hole" after the skid phase is over -- the concept makes no sense in reality. The ball is simply rolling without skidding. but during the skid phase, is there any sense in which a less-backspin-at-the-start putt reduces or eliminates the chances the ball will travel off line? Who knows? So far as I can tell, there is exactly ZERO science on this issue. But let's think our way thru it anyway.
How could one combination of more-backspin-at-the-start plus sliding friction adversely affect the line of the ball's travel MORE than a combination of less-backspin-at-the-start plus sliding friction? If the assumption is that the plane of the backspin is aligned with the line of the ball's moving across the green, then it is really difficult to see any significant difference between the two putts at all. One putt just starts out with a little more powerrful braking action, but both balls are meeting the same grass in the same way or hitting little bumps in the same way. In fact, it "stands to reason" that a ball with MORE sliding and less forward roll at the beginning will more easily plow its way thru the grass. How about meeting a bump (imagine a tiny rock that won't give or move or get knocked out of the way). In this case, the forward rolling could help keep the ball on line despite the knock from the rock. That's because the rolling of the ball sets up something similar to a gyroscope ("angular momentum and inertia") that resists change in its orientation in comparison to a non-rolling or less-rolling ball. But, hey, a backspinning ball also has this gyroscopic resistance to getting knocked off line. So the real difference DURING THE SKID PHASE depends on when the ball hits the little rock. If it hits very early in the phase, more backspin helps. If it hits at the transition between backspin and forward spin, there is little or no spin around this time and the starting conditions of the putt don't matter. Once the ball changes to forward spin, only the grass sliding friction for the ball's sideways travel matters, and this is true regardless of how the putt starts out. So from the point in the skid phase of "no spin" onwards, there is nothing about the initial backspin or lack thereof that matters.
In real terms, let's look at a 30-foot putt. With the total skid phase being no more than about 4.5 feet in length, and the "no spin" point being reached somewhere around 1/2 the way thru the skid phase, this reduces the length of the putt that concerns us to less than the first 2.25 feet of the putt. After that, nothing about the degree of backspin at the start will matter much. And even during this 2.25 feet, the backspin is nearly gone to "no spin" by about the first 1.5 feet, so we are really only talking about the first 18 inches of a 30-foot putt (once the launched ball hits the surface, that is). With that in mind, lets look at two putts: one with 3% backspin and one with 1% backspin.
How fast does a typical 30-foot putt start out? Daish describes a 10-meter putt (about 32 feet) this way: " In the case of a golf ball putted across a fairly large green in a 10-metre putt, an initial velocity of about 4 m/s is necessary. The coefficient of sliding friction in this case is probably about 0.4. Applying the equations shows that sliding occurs over the first third of a second while the ball travels a distance of rather less than 2 m." Using our units of feet per second and inches per second, Daish is saying that a 32-foot putt starts out with an initial velocity of about 160 inches per second (4 x 39.37 inches per meter), which is the same as 13.3 feet per second. A 3% putter imparts about 4.8 inches per second of backspin at the start. Within the first 18 inches, almost all of the significant gyroscopic effect is gone, and by 27 inches there is no gyroscopic effect. In comparison, the 1% putter imparts about 1.6 inches per second of backspin. In the first 27 inches of the 30-foot putt, this backspin rate has one-third the gyroscopic protective effect against a tiny rock than the more-backspin putt. Contrary to common notion, then, it would seem that the more-backspin putter offer a little extra protection for the line in the very beginning of the putt. It would be interesting to test this.
Does this matter? Either in terms of DISTANCE or LINE? In terms of DISTANCE, it would not seem to matter at all. The golfer with a 3% putter will just get used to it and will get the ball 100% of the way to the hole or not, but it won't be because his putter imparts more backspin than another golfer's putter does for the other golfer. While the "launch angle" may be greater for a 3% putter in comparison to a 1% putter, that too is something the golfer would just get used to, in terms of DISTANCE. Here, the golfer's personal consistency with whatever putter he is using is about all that matters. There is a sense in which a BIGGER energy loss may not be as consistent putt to putt as a smaller energy loss, so there is that difference, but we are only talking about the difference in consistency between 34% loss and 20% loss -- how big a difference in consistency could that account for on a 30-foot putt? I suspect not much at all.
In terms of LINE, the suggestion is that the higher backspin putter offers a little better protection to the line. But on the other hand, a higher backspin putter is also more likely to launch the ball more into the air, and sometimes funny things happen in the bounce landing because even the grass surface at Augusta National is not perfectly flat and neither is the surface of a dimpled ball. But launching issues are not the same as spin issues. Apart from this, I have a difficult time seeing what difference less-backspin at the start provides in keeping the ball on line or reducing the tendency to run off line, or seeing that any difference is significant.
There is a bigger issue, too. Whatever the magnitude of any difference, how does that difference stack up to "other fish to fry"? I a golfer just isn't consistent with distance on 30-foot putts, leaving some 4 feet short and some 4 feet long, being in this 8-foot range 90% of the time, what the heck difference does it matter to him that the putter he is used to loses 15% more energy every putt than someone else's putter? And if a golfer is consistently between 6 inches offline left to 6 inches off-line right in a 30-foot putt 90% of the time, what difference does it really make that his more-backspin-at-start putter might protect him a little more from a tiny rock in the first 18 inches of the putt, when the other putter with less-backspin-at-start offer some protection, too, just not as much? How big a chance is it that there a tiny rock in the way that you don't see?
There just isn't much difference in either LINE or DISTANCE to average golfers, except from the launching of the ball, perhaps.
Does the difference matter "much" to a VERY ACCURATE golfer in his putts? Clearly, a very good putter would not enjoy launching his putts, but other than that, what is the practical difference to such a golfer? A more-backspin putter might not have the same aesthetic appeal in the rolling of the ball as a less-backspin putter, but this is ONLY in the skid phase up to the "no spin" point (about 2 feet on a 30-foot putt). Who cares? The ball is going too fast here to tell the difference. On a 10-foot putt, it only matters in the first 6-8 inches, and again the ball is traveling too fast to notice.
So until some science shows me that the gyroscopic effect or the consistency level with greater energy loss actually matters to even a very good putter, I have serious doubts that any possible difference matters much at all.
Finally, is the trouble to get topspin worth the effort?
Notwithstanding the design characteristics of a given putter, a cagy golfer can most often still "bend the awkward tool to felicitous utility" with a properly crafted stroke. But at what cost? My answer is "some, not a little."
If I tried to use an Odyssey Two-ball putter in my natural stroke, I would probably get a big launch and a lot of backspin. If I adapted withg a different stroke to reduce launching and backspin, I would probably have to forward press, deliver the putter head low and delofted with hands ahead, and strike the ball high on the putter face. Well, geez, that's right much bother, and I might not be too good at all this complicated stuff, and I also might not be too consistent without years of training, and the bottom line is the benefit I would be gaining from all this is just not worth the trouble. Sort of "straining at a gnat." I'd probably be more successful just worrying about the "bigger fish to fry", using my limited capacity and talents on such matters as getting a good read, aiming well, stroking straight, and getting the distance correct. In the scheme of things, these are a lot more important, and I shouldn't risk getting one of these messed up chasing the Chimera of "true roll".
There just isn't any such creature as "true roll" after the middle of the skid phase. After that, all putts are the same "rolling". Once the backspin is gone in the skid phase, rolling is rolling, you know.
Granted, while there are a TINY number of golfers who after decades of training and deliberate effort are able to putt with immediate top spin, these golfers still have some skid in their putts because the top spin is not as fast as the sideways velocity of the ball at the start. But these golfers certainly have SHORTER skid phases. So what? Dave Stockton Jr. putts with a lot of top spin, and very little skid. On a 30-foot putt, his ball may skid as little as 1 foot, whereas an average golfer might have 4.5 feet of skid phase (where the first 2.25 feet matter a little). The avergae golfer would appear to benefit from the backspin at the earliest part of his skid phase; and Dave Stockton Jr. will also have some good gyroscopic forward spin going in his skid phase also, so he benefits. Who benefits most? I don't know. I do know who had to go to the most trouble, though -- Dave Stockton Jr.
On short putts, probably what matters more than backspin or top spin is the launch angle of the ball at the start.
In summary, the science is "missing in action" a) a little bit on exactly how spin gets generated (whether there is one and only one way and whether the explanation of Dr Lindsay is total and complete or whether there is still more to learn), and b) the science is "missing in action" altogether on the best way fro the human actor to move to help reduce backspin or promote forward spin, and c) the science is "missing in action" altogether on how much difference it makes, and d) the science is "missing in action" altogether on what the trade-off is in trying to gain whatever the benefit might be.
Launch angle is probably more important than backspin / top spin at the start. This suggests less loft, independently of the location of the COG in the putter design. And Dr Lindsay says that the least loft allowed by the greens you play is probably best, and negative loft may not be bad at all. I agree. I think that the usual 3 degrees of loft (recommended by Scotty Cameron and most others) is a bit much for today's greens and unhappily promotes launching the ball too high, or forces golfers into stroke weirdness to avoid the launching.
I expect the near future will show signiifcant changes in putter designs for the lofts and also for the COG. This will trend towards a less manipulative stroke style. I'm waiting.
Cheers!
Geoff Mangum
Putting Coach and Theorist
PuttingZone
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