Roll and Distance

Roll and Distance

SoCal Golfer
SoCal Golfer

June 12th, 2006, 6:27 pm #1

I have been reading various posts on the board and wanted your insight. Can you please describe the physics of spin rate (Backspin, Neutral, or Topspin) after impact as they relate to the overall distance a putt travels?

Thanks,

D
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Geoff Mangum
Geoff Mangum

June 14th, 2006, 8:04 am #2

Dear D,

More backspin means more energy loss from skid, and less energy means shorter total roll.

More topspin means less backspin, and less backspin means less energy loss from skid, and less energy loss means greater total roll.

Solid impact means total energy transfer from putter head to ball, and off-sweetspot impact means less energy transfer from putter head to ball.

Impact ABOVE the putter head's Center of Gravity (COG) in the up-down dimension means less backspin due to the gear effect (and therefore more total roll), but impact off the sweetspot means less energy (and hence less total roll), so there is a conflicting tendency here in terms of total roll.

According to Dr Norman Lindsay, the preservation of roll energy from reducing skidding more than compensates for loss of impact energy tyransfer from off-sweetspot impact designed to promote more topspin and less backspin. He also says that a soft insert on the putter face tends to mask your noticing whether impact is on, above or below the sweetspot.

His testing of the Odyssey Two-Ball putter showed a LOW impact from a rising blow lost 34% of the energy over the skid phase of the putt. A putter and impact that lost a lot less energy (say, 20%) over the skid phase of the putt would go further, perhaps 14% further (not sure about this proposition). So for a longish putt, one putter and impact would send the ball off with backspin and lose 34% energy in the skid and go a total distance of 20 feet, whereas the other putter design and impact would send the ball off with less backspin and only 20% energy loss during skid, for a total roll distance of perhaps 20 feet plus 14% more (2.8 feet further).

Personally, I find that a light grip and an impact "high" on the putter face ABOVE the putter head's COG does promote less backspin and greater total distance of roll, even though the impact may not quite feel solid 100%. However, I have to question placing "true roll = maximum distance" as the premium. I don't really want maximum distance from a "pretty" roll -- instead, I want CONSISTENT and PREDICTABLE distance from a roll that does not go off line.

For me, then, there is nothing different between a pretty "topspin" roll and a roll with MORE skid at the start -- they both have skid and they both can be used consistently with predictable total roll distance. The only difference would be whether one sort of roll IN THE SKID PHASE significantly affects the line of the putt in a bad way. (After the skid phase ends and the ball is solely rolling, there is no such thing as "true roll" -- true roll, topspin, and backspin matter ONLY in the extent of the skidding of the ball at the very start of the putt.) Until I am convinced that bad things happen to the line of roll as a result of a small difference in backspin (a little more) from going for solid impact rather than going for "more topspin", even if solid means less "gear effect" and less "topspin", I personally prefer the certainty of "solid" over "topspin."

So far as I can tell, "solid" equals "straight." Also, "simplest" equals "best" and "least" equals "simplest." For me, ANY complication in the stroke has to prove its worth before I will allow it in. To the extent I can avoid putters that have a COG located above the point on the face where my normal stroke strikes the ball, that is free and does not involve technique or stroke dynamics, so I will look for putters with that feature. But I don't facvor "reaching" or "trying" for a certain sort of technique in the stroke that positions the impact point ofn the putter face so as to chase after an improved roll during the skid phase.

We need some data about the difference backspin makes on the line of the putt.

So, to answer your precise question, backspin starts don't roll as far as the same putt with less backspin.

The question is whether it's worth the trouble.

Cheesr!

Geoff Mangum
Putting Coach and Theorist
PuttingZone
http:puttingzone.com
Golf's most advanced putting instruction.
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sammy
sammy

June 14th, 2006, 4:52 pm #3

Well stated Geoff .... and I like your philosophy of "solid, straight and simple" ... because that is what is humanly controllable during the putting stroke and subsequent impact event. After the ball leaves the putter face it enters a random world of chaos, bifurcated by an errant blade of grass or divot repair.

When you state: "We need some data about the difference backspin makes on the line of the putt." .... I would add that the mysterious coefficient of friction between the moving ball and the grass surface may supercede any consideration about initial ball spin direction. Surely the grass surface is too variable and the vagaries of grass blades and ground are too significant for anybody to neurotically worry about initial post-impact conditions.

If one can better one holed putt in four from 10 feet, one is a statistical winner ... and I don't mean four consecutive putts from 10 feet ... I mean four putts on four greens separated by fairways ... or ... four putts at 10 minute intervals ... you know what I mean ..... !!!!

Regards .....
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