Dear Tim,
I like the added concept of the polymer between the edges of the grooves as opposed to clear air / space, and I don't doubt that there is some improvement over "typical" putters, but as usual I question the magnitude and effective significance of the difference, especially in comparison to good technique with a "typical" putter.
The graphics on
the Taylormade website for the "technology" of the putter ASGI insert is a bit misleading (nearly all companies use misleading graphics). In particular, the indication of what is "skid" and what is "forward roll" is not correct. Taylormade has the point of "forward roll" appear as soon as the ball launched with its putter returns to the surface (third ball image after impact). The two images of "typical" putts are "high launch" and "low launch" strokes. (My counting of balls starts with 0 at the putter and the 1st ball thereafter.)
The high-launch graphic shows a ball with backspin that lands after two mid-air balls and hops a second time and lands after one mid-air ball and then starts forward roll. As soon as the second hop lands (5th ball), the graphic says the roll direction reverses from backspin to forward spin, but the "bar" underneath to indicate when skid stops and forward spin starts is two more balls along.
The low-launch graphic has the ball hit down with the 1st ball immediately in contact with the turf with forward roll, but then bounding up in the air for one ball, landing (3rd ball), and then bouncing up for two balls before landing again (6th ball). All of these balls indicate forward spin direction, yet only the 6th ball is where skid is said to end and forward rolling to begin.
The main problems with this graphic are two: First, the skid / roll boundary is not a point as indicated but is a transition zone from 100% skid - 0% roll to 0% roll - 100% skid. Second, the fact that backspin goes away or that a ball first contacts the surface with "some" forward spin does not mean the skidding is over (0% skid) -- it only means that the backspin is over and then the question is whether the forward spin is fast enough to keep up with the translational / sideways velocity of the ball. So skidding is really two separate parts - eliminate any backspin and then start the transition from 100% skid - 0% forward roll to 100% forward roll - 0% skid. The transition phase always lasts from "X velocity" of translational speed when the ball first meets the friction of the surface (after launch and / or bouncing) to the point in the putt when the translational velocity of the ball has been slowed by the green friction to 5/7th X. The skidding-that-ends-backspin actually results in the skid-forward roll transition phase starting at a lower X than otherwise, thus shortening the transition phase once the backspin is all gone.
The total length of the first section of a putt before the ball settles down and simply rolls is partly the launch and bouncing / bounding and partly the skid-roll transition phase, so it is a bit unfair or misleading to compare putts that feature a lot of launch and /or bouncing / bounding with putts that start on the ground meeting green friction right away.
So the Taylormade graphic "implies" that the ASGI insert somehow avoids big launches and bouncing / bounding beginning, in addition to implying the ASGI starts the ball off with forward roll. Note that the low-launch typical putter also starts the ball off immediately with forward spin according to the graphic, but this ball stays airborne for three of five images before forward roll starts on the sixth, according to the graphic.
It should be pretty obvious that an airborne ball is not in contact with the surface, and so the surface friction is not doing its job of countering backspin and / or promoting forward roll. This means that the sooner the ball engages the surface friction, the sooner the skid is over; and that the greater the green friction, the sooner the skid is over; and that the less backspin the ball starts with, the sooner the skid is over; and that the more forward spin, the sooner the skid is over; and that the closer the forward spin is to the translational velocity of the ball when the ball engages the surface friction, the sooner the skid is over; and that the slower the translational speed when the ball engages the surface friction, the sooner the skid is over in terms of absolute distance of skidding.
Does the ASGI avoid launching the ball? Unlikely. Launching the ball is more a matter of loft design and stroke technique in terms of how the putter face impacts the back of the ball. The graphic SHOULD indicate the relationship between the loft angle and the back of the ball to show whether the rectangular slab of the putter head meets the ball at a point below the equator with the slab aiming / moving thru the ball on a rising line, whether the putter head slab meets the back of the ball on the equator with the slab aiming / moving on a level line thru the ball, or whether the slab meets the ball at a point above the equator aiming / moving on a descending line thru the ball; should indicate HOW MUCH above or below on what angle off level; and also should indicate whether the trajectory of the slab thru the space of the ball penetrates thru the ball's sweetspot (center of sphere) or above it or below it and how much above or below. All of these parameters affect the launching of the ball. Instead, the Taylormade graphic is very unclear and suggests that all three putters meet the ball in a neutral orientation on the equator. This happens in reality about as often as the kid at the carnival gets the ring tossed onto the peg and wins a teddy bear. usually, the putter slab meets the ball below the equator rising thru the ball unless the golfer incorporates a special technique in his stroke.
Does the Taylormade ASGI technology add forward spin to the ball? Possibly, but not proven by this information. How a putter in terms of design and dynamic stroke parameters avoids backspin and adds forward spin immediately upon impact is a bit of a mystery. There are three main suggestions for how this happens in physics: 1. oblique impact; 1. vertical gear effect; and 3. top-over impact from low to high thru ball. What do these mean?
An oblique blow is delivering the slab of the putter head angled down to meet the ball on the top quadrant above the equator with something of a glancing scrape-up-over-the-top-quadrant blow, sort of like a kid with a flat paddle swatting the top half of the back of a hoop to roll it down the street. This is what Harold Swash teaches -- hands ahead delofting the putter slab making a rising blow up across the top quadrant of the ball, with grooves to "grab" the cover material so the glancing blow doesn't simply slip on the ball. I believe Dave Stockton Jr. has a similar technique.
The vertical gear effect is describe by Dr Norman Lindsay as partly putter design and partly stroke technique to deliver the putter slab to make contact with the ball on a point on the face higher than the putter head center of gravity, which should be low and recessed and the loft should be minimal for the surface. This is said to generate a "gearing" of the putter head wrapping up over the top of the back of the ball, reducing backspin and promoting forward spin. Whether and to what extent the hoseling of the shaft on the top of the putter head affects this gearing is not known clearly (if at all), but interestingly the Zen oracle designer Nick Middleton has a patent on a hosel feature at the end of the shaft and beginning of the putter head that is a flexing insert that lessens any resistance of the hoseling to the vertical gearing over the back top of the ball.
The "top-over impact from low to high thru ball" is something I alone describe, from my intuition using physics knowledge. In billiards, a "level" blow with the cue stick thru the top quadrant of the ball at the height of 7/10th the diameter up from the bottom of the ball produces physics such that the translational velocity is immediately matched by the rotational velocity and there is 0% skid immediately. (This is what the Tear Drop roll-face putter designs tried to achieve, a "level" blow with impact at this specific height.) What this elaborate geometry really means, however, is more generally stated: if you swat the top half of the ball over the lower half, you get forward spin. That general rule underlies the "oblique blow" and the "billiards 7/10th level blow" and probably also the "vertical gear effect." So how do you accomplish this? The main point in physics in a collision between two objects or masses is the relative velocities COMBINED with the trajectory of the blow in terms of one mass' center of gravity and the other mass' center of gravity. It matters whether the blow proceeds with the putter head's moving COG passing dead thru the ball COG, above it, or below it. It also probably matters whether the putter face of the slab is flush to the trajectory thru the ball, whatever that trajectory is, so there are "solid" blows where the putter face is flush with the trajectory thru the ball but the trajectory does not pass thru the ball's COG and then there are "SOLID" blows where the putter face aims thru the center of the ball on contact and also moves on a trajectory thru the center of the ball. Launching the ball is maximized when the putter face meets the ball below the equator aiming upward and moving thru the center of the ball, more and more so as the angle of the blow increases while the putter head stays flush thru the ball's center. A "top-over impact from low to high thru ball" is referring to a blow in which the putter face meets the ball below the equator aiming higher than the ball's COG. This blow effectively hits the top half of the mass of the ball and the bottom half wants to stay in place, so the ball gets knocked top-over-bottom, like kicking a milk can in the top half so the bottom stays put and the can flaps backwards onto the ground. Apparently, this sort of blow can also works with vertical gearing, so long as the point of impact on the face is lower than the putter head COG and the COG is recessed back from the putter face. In terms of the loft of the putter, there is design loft and then there is added or subtracted loft by the stroke technique which (combined) results in a "dynamic loft" at impact. You can get the "dynamic loft" you want by adjusting technique to almost any reasonable putter design loft, but the bottom line seems to be that a dynamic loft at impact that is aimed on a rising trajectory thru the ball of around 5 degrees off level works pretty well in reducing backspin, especially when combined with vertical gearing and a low-velocity, smooth stroke.
So the Taylormade graphic has a few misleading aspects and doesn't really grapple with the real physics issues in a revealing manner.
But in general I like the Taylormade Corza model for its MOI physics, its face balancing, and its center shafting, and the face insert seems okay as well. Combined with a propitious stroke technique, this putter ranks right in the top five of today's offerings, and possibly in the 1-2 fight without a clear winner.
Cheers!
Geoff Mangum
Putting Coach and Theorist
PuttingZone.com
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