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By Mike Stachura
The Cleveland Frontline putters stand as a counterargument to everything you thought you knew about putters and off-center hit forgiveness. Specifically, we’re talking here about the property of moment of inertia (MOI), which is a measurement of an object’s resistance to twisting on off-center hits.
In putters, MOI has been a kind of selling point as oversized mallets and multiple material designs have touted their off-center hit performance where mis-hits roll with nearly the same ball speed as center hits because of the overall stability of that design. Typically, that stability comes from a design where the center of gravity is pushed away from the face in an oversized mallet shape.
But Cleveland’s design team not only thinks the way high MOI has been traditionally engineered isn’t necessary, and it’s actually making your putts roll farther off-line than they should. In other words—and we know this might sound like a shock to those who think they understand a little about equipment technology—but a high-MOI putter is not going to produce straighter mis-hits.
“It’s a fundamentally new approach to putter design,” said Jacob Lambeth, research engineer for Cleveland, who said the Frontline putters’ performance benefits mean that the same putt mis-hit off the toe that would have been missed from 10 feet would now instead find the hole at nearly 15 feet.
What sort of magic is Cleveland talking about with the Frontline putters? Well, it’s a combination of a face pattern and a center of gravity that’s not deep (like in high MOI putters) but actually fairly close the face. It does so by inserting heel and toe tungsten weights not toward the rear of the head but inset right into the face. A CG closer to the face is the key, Lambeth said. It has to do with what’s called the azimuth angle, a measurement that refers to the way the face rotates on an off-center hit.
Even on a putt, those mis-hits create some face movement. Lambeth said that when the center of gravity is farther away from the face that azimuth angle is greater creating a greater rotation. That means a typical mis-hit off the toe is going to start farther right of the hole for a right-handed player.
“Putters are often designed with a deep cg to help with ball speed on off-center hits because of high MOI but that ignores azimuth angle,” he said. “It’s complicated because when it comes to the azimuth angle, it relates to the CG depth and the MOI, but generally speaking it’s more sensitive to the CG depth than it is the MOI.
“The reason why we haven’t done this in the past is because if you were to move the CG forward then, yes, your toe hits might stay more on-line, but you’re going to lose a lot of ball speed. So there’s going to be a negative effect overall. But if we can retain that ball speed, then we can focus on that CG depth and focus on the azimuth angle.”
So the challenge for Cleveland’s design team was to find a way to retain ball speed on off-center hits without having to resort to a deep CG and a high MOI. Not a problem because the team already has figured out the problem of retaining off-center hit ball speed. Seen in past versions of its TFI and HB Soft putters, the Frontline putters use a milling patter on the face that’s geared to each of the four heads in the collection (one blade, three mallets).
Called “SOFT” for “speed optimized face technology,” Lambeth said the face designs basically replicate the off-center hit benefits of a high-MOI putter by using a pattern of S-shaped grooves running vertically across the putter face. A more compressed pattern in the center slows ball speed, while wider spacing allows for more direct energy transfer.
Lambeth led the team of Cleveland Golf engineers that presented their findings on this idea during the 2018 International Sports Engineering Association’s bi-annual conference last year. In the paper, the team notes that a high MOI putter loses 6.5 percent of ball speed for a one-inch mishit and a conventional MOI putter loses over 10 percent, resulting in a performance curve that shows steep falloffs as the impact location moves laterally away from the center: “[But] using a variable depth and pitch milling pattern, ball speed normally lost on off-center hits can be recovered. By considering the exact relationship between the milling properties and ball speed, along with the putter’s inertial response on off-center impacts, this curve can be made perfectly flat within our model."
The result is off-center hits roll with more speed than on-center hits, similar to the ball speed results a high-MOI putter would produce on a flat face putter. The difference is the Frontline putters use a CG closer to the face so the putter doesn’t rotate as much on an off-center hit, sending the ball off on a greater angle. Cleveland’s research says these face patterns reduce that mis-hit directional angle by half-a-degree to nearly two degrees on off-center hits of three-quarters of an inch.
“We’ve perfectly counteracted the distance you would have lost by hitting it off-center,” he said. “This just wouldn’t be a good idea if we didn’t have the face technology.”
The Frontline putters also feature the company’s aiming technology that features alignment marks set at 21.35 millimeters above the sole of the putter to match up with the center point of the ball. The intent is to make it easier to align the putter to the target regardless of a player’s eye position at address.
The four models in the line include the Frontline 4.0 Blade, and the Elevado, Iso and Cero mallets. Each of the mallets is offered with a hosel for either a face-balanced design or a toe-hang design. Available Sept.