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Tuesday, April 24, 2012
Underrated Aspects of Driver Head Designs
of the big eye openers for me when I started learning about club design, club
making and club fitting was from Tom Wishon’s book ‘The Search For The Perfect
In the book, he discusses the fallacy of the ‘hot spot’ of the
driver. The fallacy goes as this….there’s supposed to be a ‘hot’ spot of the
driver head up towards the top of the face (near the crown). This is a fallacy
rampant throughout the golf industry. I’ve seen Martin Hall talk about the ‘hot
spot’ in his show on The Golf Channel and heard this quite a bit at the PGA
Merchandise Show this year.
THE REASON FOR THE
Wishon’s explanation of the fallacy was that the face of
the driver curves vertically (bottom to the top of the face). This is called the
‘face roll.’ With 460cc driver heads, the clubface became longer both vertically
and horizontally. Since the face became longer vertically, the face roll became
more pronounced. And when that happened, the clubface would increase in loft
towards the top of the face and decrease in loft towards the bottom of the
roll wasn’t a problem pre-titanium. As you can see the difference between a
persimmon driver and the titanium driver in the photo above, the pre-titanium
driver heads were so small that the face roll was not as pronounced.
A LITTLE SIDE BAR ON LOFT FITTING
driver it’s ultra-important to fit for loft. 1° of loft difference in a driver
can greatly influence how well you hit a driver. However, Wishon recommends that
you first look at clubhead speed in order to start to fit for loft. The more
clubhead speed, the less loft a golfer should use. And of course, attack angle
plays a factor as well. But most of the time, it’s far more about clubhead speed
in loft fitting than it is attack angle. This is something most golfers either
don’t get or go the opposite way (thinking attack angle first, then clubhead
BACK TO THE REASON FOR THE FALLACY
according to Wishon, the reason for the fallacy of the ‘hot spot’ was that
golfers were playing with drivers that had too low of a loft for their clubhead
speed. They would then hit the occasional shot up high on the face where there
was more loft which fit their swing better. So a golfer who swings the driver at
100 mph may be best off with a driver with a 11-12° of loft. Instead, they are
using a 9.5° lofted driver head. Eventually they discover when they hit the ball
up high on the face, they hit it longer. But in reality they are just hitting
the ball on the part of the clubface more where the loft is comparable to their
One of the things I hear some clubmakers talk
about is how the Quality Control of OEM drivers is poor. I usually hear that the
lofts are higher than the what they are stamped on the club. So, you may hear a
clubmaker say that he has a driver that has a stamped 10° loft, but when they
measured the loft, it was actually more like 11.5° loft.
club can have the incorrectly stated loft from time to time. However, the loft
of a driver is measured from the center of the face. Thus, if a clubmaker is
measuring an OEM driver and happens to measure more above the center of the face
where the loft has increased because of face roll, then they are not quite
getting the most accurate measurement of loft.
SIDE EFFECTS OF BELIEVING IN HOT SPOT HYPE
One of the questions
that a reader asked me was ‘if you can hit the ball further by hitting above the
sweetspot, then why not just keep hitting the ball above the
I thought about this for a while and I’ve come up with a few
reasons to avoid this:
1. Toe shots
From my personal
experience of believing in the hot spot hype and then getting out of that hype
is that my toe shots off the tee dramatically decreased just by no longer trying
to hit that ‘hot spot.’ First, the ‘hot spot’ is alleged to be slightly towards
the toe. So, if you try to hit slightly towards the toe…your chances of hitting
one woefully off the toe increases. I also find that swing mechanics wise, if
you try to hit the ‘hot spot’ and in particular try to hit up on the driver and
hit the ‘hot spot’, I think that tends to cause your swing mechanics to be more
likely to hit that toe-hook shot. I don’t have a problem with hitting up with
the driver, but you should hit up and try to hit the actual sweetspot instead of
trying to hit up and hit the faux ‘hot spot.’
2. Less Distance
Off The Hot Spot
The closer you are to the sweetspot (somewhere
in the center of the face, aligned with the clubhead’s Center of Gravity), the
clubhead’s Moment of Inertia is at its highest. The higher the MOI, the less
twisting of the clubhead as the ball hits it.
You will hit the ball
further with less twisting from the sweetspot than from the Hot Spot. I don’t
think it’s a giant difference because I think the ‘hot spot’ still has a rather
high MOI, but not as much as the optimal MOI of the sweetspot.
general, I think golfers will be much more accurate and consistent to avoid
trying to hit the faux ‘hot spot.’ But, I think those 2 reasons above are the
things that become obvious once you stop believing in the hot spot
WISHON AND GRADUATED ROLL TECHNOLOGY
of the things Wishon Golf decided to do was to counter how much the loft of the
driver can change because of the pronounced face roll. So what they created was
something they call ‘Graduated Roll Technology.’
Technology (GRT) keeps the face roll down to a minimum.
The main benefit I’ve found of GRT is that it allows the
golfer to increase their distance off the tee *over the course of a
What I mean by this is that a properly fitted Wishon driver and a
properly fitted OEM driver will likely go about the same distance when they hit
the ball on the sweetspot.
However, we don’t always hit the sweetspot.
And often times we may not hit it off the toe or the heel, but just miss the
sweetspot by hitting it a little too high or too low off the face. Usually these
shots wind up fine, but they just don’t go quite as far as we would
GRT & VERTICAL GEAR EFFECT
discussed something called ‘vertical gear effect.’ Vertical Gear Effect is
similar to Horizontal Gear Effect in that it helps ‘self-correct’ the golfer’s
ball flight when they miss the sweetspot.
For example, with horizontal
gear effect…if I hit a shot off the toe the ball will have hook spin to it. So
the horizontal gear effect will launch the ball out to the right and the ball’s
hook spin will bring it back towards the target. Without horizontal gear effect,
we would miss the target badly every time we missed the
Vertical gear effect works in a bit of a similar fashion.
If I hit a shot with the driver above the sweetspot, the ball will
initially launch higher. You can lose a lot of distance, but the vertical gear
effect will produce less spin. The lower spin allows the ball to not go too
high. This is another reason behind the ‘fallacy of the hot spot.’ Golfers would
hit the ‘hot spot’ and the ball would carry better for them and with less spin.
Conversely, if you hit below the sweetspot, the initial launch of the
shot will be lower. So the vertical gear effect kicks in and the ball will spin
more to help bring the trajectory up.
So, let’s take the difference
between a driver with GRT and one without. We will say that both are optimally
fitted for the golfer and the golfer understands the fallacy of the
the golfer is using an 11° loft driver in both cases as that is what they were
optimally fitted for.
Hits Above The Sweetspot
golfer will actually hit the GRT driver further because while the loft is higher
with each driver, the GRT loft is more in line with what they were fitted for.
The vertical gear effect will help bring both trajectories down. The difference
in lofts here above the sweetspot is 1.5°.
Hits Below The
The GRT driver will go much further because the loft
has not changed from what they were fitted for. However, the non-GRT driver has
a much, much lower loft. The difference in lofts is now 3°. Imagine having the
choice of buying 2 drivers with a difference in 3° of loft. That’s a massive
So over the course of a round, the golfer would likely pick
up yardage because when they go above or below the sweetspot, the GRT driver
consistently allows them to hit the ball further.
DRIVER OFF THE DECK
all of this being said, another benefit is that better players are in a better
position to hit driver off the deck with a GRT driver than a non-GRT
Think about it for a second. If you hit a driver off the deck,
the ball contact will be lower on the face. With a non-GRT driver, the loft will
be very low on that part of the face. While the Vertical Gear Effect can help,
the loft may just be entirely too low with the non-GRT driver off the
Perhaps the player on Tour that uses the driver off the deck the
most is Bubba Watson. I think Bubba faces the same issues with his non-GRT PING
driver. However, his clubhead speed is so high (around 125 mph), that allows him
to more easily (and naturally) get the ball up in the air. But for mere mortals,
even those who generate a good amount of clubhead speed (say, 112-115 mph),
using a non-GRT driver off the deck is a difficult proposition
point in all of this is to really try and understand your equipment. Even if you
utilize a non-GRT driver, you can still hit a driver really well. But, you are
likely to become a better driver if you truly understand the features of the
clubhead design than if you are going into it blind.