Lie Angle
What it is and Why we care
The lie angle
of the club is the angle the shaft makes with the ground,
when the club is in the proper address position with the grooves level.
There is a defacto or nominal "standard" lie angle for each iron.
If a club has a higher lie angle than standard, it is called "upright";
if lower, it is called "flat".
For instance, the normal lie angle for a 5iron is 60 degrees.
A 5iron with a 58degree lie would be called "two degrees flat".
A player with a particular size and swing will require a particular lie
angle
in order for the clubface to be level at impact. And it is important
for
the clubface to be level at impact. The reason? The direction of the
clubface at impact varies with lie angle. And it can vary even more if
the ball is hit a little fat.
Direction of clubface
The more toedown the club, the more the clubface will face to
the right
(for a righthanded golfer; we'll use the righthanded convention from
now on).
The result will be a push, but
the rightfacing clubface will also impart some slice spin that will
magnify
the effect.
The figure should help you visualize this.
Take a welllofted club (a short iron)
and hold it with the shaft perfectly vertical. This will simulate a
seriously
exaggerated tooflat club (i.e., toedown) for the very upright
position in which you're
holding it. Notice how the face is pointing not just up, but well to
the
right as well.
Conversely, if you hold the shaft horizontal, the
clubhead is toeup,
or "upright". And the face points well to the left.
By the way, this is the same reason that a sidehill lie
with the
ball
below your feet is a "slice lie" and with the ball above your feet is
a "hook lie". With the ball below your feet, the shaft will be more
vertical than the design of the club; with the ball above your feet, it
will be more horizontal.

How much of a directional error will you get from an
error in
lie angle? The greater the loft, the greater the angle of error. The
formula controlling the directional error is actually pretty simple:
DirectionalError
= Loft * sin( LieError )
If
the loft is zero, then lie errors don't matter. (Well, they matter if
you hit it fat. We'll see this in the next section.) If the lie error
is zero, then there is no directional error. Here's a table of where
the clubface points for various lofts and lie errors.

Lie error 
Loft (degrees) 
10 
20 
30 
40 
50 
1 
0.2 
0.3 
0.5 
0.7 
0.9 
2 
0.3 
0.7 
1.0 
1.4 
1.7 
3 
0.5 
1.0 
1.6 
2.1 
2.6 
4 
0.7 
1.4 
2.1 
2.8 
3.5 
5 
0.9 
1.7 
2.6 
3.5 
4.4 
6 
1.0 
2.1 
3.1 
4.2 
5.2 
This
says that the greater the loft, the greater the error. But that is the
angular error; the error in yards is not so cutanddried. That's
because the greater the loft, the less the distance  so the angle of
error doesn't matter as much in yards. Here is a table of total
directional error (in yards) for a variety of clubs, due to each
degree of lie error.
Club

Loft

Distance
(yards)

Face Angle
Error
(degrees)

Yards
Error

Driver

10

250

0.17

2.5

3iron

20

190

0.35

2.8

6iron

32

160

0.56

3.2

9iron

44

130

0.77

2.8

Sand wedge

54

100

0.94

2.0

The table takes into account both the initial directional error and the
slice due to the open clubface. I used a rule of thumb that I derived,
multiplying the
directional error by a "curvature
factor"
to include slice. The factor itself increases with distance, in
opposition to the face angle error. So the yards of error reach a
maximum for a sixiron. But all the irons have an error of roughtly 3
yards for every degree of lie angle error. That's not trivial; three
yards, or 9 feet, can easily be a stroke difference for a good golfer
 the difference between a tapin and a 10foot putt. And that's just
a one degree lie error. 
Twisting with Ground Contact
So far, we have been talking about directional errors with a
good
strike. Now let's discuss what happens if you hit it fat  if the sole
of the club hits the ground before the clubface reaches the ball. Yes,
that will cut yards off the shot, but it will also exaggerate the
directional error.
A club with the proper length and lie will, at the bottom of
the swing
where the club meets the ball, have the head perfectly level. An
important
consequence of this is that the club strikes the ground at a point
directly
under the sweet spot of the clubhead; this is also directly under the
ball,
assuming the golfer has managed to strike the ball on the sweet spot.
But what happens if the club is not the right lie? Let's
consider the
tooflat or tooshort club, which is toedown as it strikes the ball.
The toe will strike the ground first, and twist the clubface open.
If you hit the ground before the ball (that is, hit it fat),
this twisting
of the clubface greatly multiplies the small directional error we had
before due to the flat lie.
Now you don't have a small push or slice; you could have a disastrous
one.
If the club is too long or has a tooupright lie, the opposite is true.
The club will face left at impact, encouraging a pull or a hook. A fat
hit will further close the clubface, giving a potentially disastrous
pull
or hook.
Last modified May 22,
2017
