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Toe up/toe
down deflection is illustrated
by the blue line on the swing profile chart. Because the club
head mass is at the end of and trailing the shaft during the
first part of the downswing, inertia prevents the head from
accelerating as rapidly as the rest of the club. This results
in a 'toe up' bend. As the wrists rotate the head to a position
beside the axis of the shaft (perpendicular to the swing plane),
the head inertia then causes the shaft to eventually flex
in the opposite direction. This is seen as a 'toe down' bending
closer to impact.
The toe up/down (blue) line will be
typically be in the shape of: 1) a double
peak, 2) a single peak, or 3)
or ramp. Keep in mind that many profiles
have characteristics of more than one of these shapes. Some
profiles will be a hybrid, or combination of two of the basic
shapes. The curving irregular lines on the profile chart represent
the bending (or deflection) of the club during the downswing.
The numbers on the profile chart are measurements and calculations
made from the portion of these data curves before (to the
left of) the point of impact.
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Clubhead
Droop at Impact: Just
prior to impact, the golfer has typically ceased most or all
acceleration (not motion) of the club. The inertial effect
lessens and the shaft tends to spring back from a toed down
position to a motion in the toe up direction before striking
the ball. ShaftLab measures the distance the head is toed
down at impact as Clubhead Droop at Impact (droop is
another term for toe down). The shaft also springs from a
lagging to a leading state; this motion 'kicks' the ball at
impact. In other words, the spring action of the club allows
the head to momentarily travel at a faster rate than the butt
end of the club.
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Lead/lag deflection
is shown as a red line on the swing profile chart. As the
downswing begins, the clubhead is typically in general alignment
with the swing plane. The amount of lead/lag is an indicator
of the angle of the clubhead in relation to the swing plane.
As the club head is rotated to face forward the head's inertia
causes it to gradually lag behind the shaft axis. However,
just prior to impact the golfer has typically decreased or
ceased acceleration (not motion) of the club. The shaft then
springs back in the other direction and overshoots, resulting
in the head leading at impact. The amount of lead at this
instant is measured as Clubhead
Lead at Impact. The red line also indicates your club
face angle during the downswing. If the red line stays above
zero, the club face is open. If the red line stays below zero,
the club face is closed. If the red line stays on the zero
line, the club face is parallel to the swing plane.
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Downswing
Time is the amount of time
measured between two points in the golfer' s downswing. The
starting point is the beginning of the downswing. The ending
point is the instant of impact. The average downswing time
is about one half of a second. Some people only take about
three-tenths of a second while others take as long as nine-tenths
of a second. Neither extreme is necessarily good or bad .
If general, a golfer with a shorter downswing time requires
a stiffer shaft than a golfer with a longer downswing time.
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Maximum Shaft
Deflection is the maximum
amount of shaft deflection (or bending) that occurs during
the downswing. It is calculated by combining the readings
from both gauges (the vector sum) and measuring the highest
value found. The peak deflection value is the primary factor
in determining a golfer's overall flex requirement.
Most profiles can be characterized in
terms of the shape of the toe up/toe down curve (the blue
line).
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