In the early 1970s, Joseph Braly was the chief
scientist for Brunswick Shafts, which eventually
became Royal Precision. He came up with the idea
of frequency matching at that time, and ran a
bunch of human-golfer tests to see what frequency
really meant. The outcome of these tests was that
different golfers perceived flex differently but,
when the data was statistically processed, the
best fit to a CONSTANT PERCEIVED FLEX was when
the frequency was sloped. The slope Braly came up
with was 8.6cpm per inch, with longer clubs
wanting a lower frequency to be perceived as the same stiffness by the golfer.
Since that time, Precisions and Rifles have been
built to 8.6cpm per inch (or 4.3 cpm per club at
a half-inch length spacing across the irons). The
other major shaft manufacturers had trim
schedules that supported similar slopes. I don't
know what the PCS "system" is, and would be
interested to know if it endorses some particular
slope, either explicitly or implicitly.
There have been quite a few golfer tests since
Braly's original experiments, and they almost
always seem to come up with a similar result. The
slopes are between 7 and 11cpm per inch for all
tests that I've seen save one. That one was done
by Eric Cook, founder of the Canadian company
Swing-Sync. What they sell is constant-frequency
matching, and that is what Cook's reported tests
showed. I tend to discount his results because:
* Every other test I've seen comes up
with a definitive, non-zero slope.
* I've read a bit of the test protocols
for Cook's experiment, and feel it was biased to show a constant frequency.
* Over a 40-year career, I've been close
enough to instances of "sponsored research" to be
suspicious of any study funded by Company XYZ
whose outcome supports the product of Company XYZ.
Anyway, that's how we got to where we are today.
DaveT
At 08:04 AM 8/25/2006, André Cantin wrote:
I was in the Canadian GW store yesterday and had a good conversation with
one of the managers who took the Rifle training before they went belly up.
According to him a flat line(single frequency) set does not produce the same
flex across the set. In his opinion the short irons are softer in flex than
the long irons. Of course his statement is based on a frequency chart where
the same frequency at a shorter length yields a softer flex. He also
believes that a shortened club(leaving the tip as is) yields a softer flex
as you are cutting away in the stiffest part of the shaft(butt section) and
obviously just the opposite if you lengthen the club. I would like to know
your opinion as I have read in many books that by shortening a club you make
it stiffer. Swingweight is not part of the equation in this discussion. I
also have always thought a single frequency set yields the same flex across
the set Thanks.
André.
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