Effects of Clubhead Features
of Gravity ( CG )
center of gravity can vary in three different dimensions:
| Heel-to-toe:||There are some that feel that increased
toe weight helps pull the clubhead through the ball and prevents
slices. I'm not convinced yet. However, the Ping Zing seems to indicate
that Karsten is convinced. Same for Golfsmith's Square Toe models,
Acer's "flow-weighted design", and several heads from ProSwing. So
either it works, or people are buying based on the perception that it
That may or may not be true for irons. For
woods, the gear effect
will make it work just the opposite. By moving the weight towards the
heel, you are promoting a hook. That is because more of the clubface
will be on the toe side of the CG, and gear effect causes a toe hit to
hook. But it takes a lot of weight to move the CG appreciably to the
heel or toe. Weight screws in the 8-12g range are not going to have
much effect on CG placement -- and therefore not much effect on
| Face-to-back:||This is the
cause of "gear effect".|
| Height:||Aha! This
A low CG tends to give a high trajectory (flight line) to the ball, and
vice versa. So:
Many peripheral-weighted (cavity-back) clubheads have a big sole
flange, that keeps the CG low and gets the ball airborne.
- If you tend to have
trouble getting the ball airborne, go for a low CG.
If you want to keep your shot lower out of the wind, go for a high CG.
If you want your drive to carry in the air, go for a low CG.
If you want your drive to roll a long way, go for a high CG.
short-hosel or no-hosel clubheads are designed for a low CG. For
instance, in the early-to-mid 1990s, Acer made two nearly identical
clubheads, the M160J and the M360J. Same loft angle (10
degrees), but the short-hosel 160 gives a high flight, while the
high-CG 360 gives a flat trajectory and lots of roll.
- It is possible to get woods with
an open face angle or a closed one. For instance, some closed-face
woods are advertised as "curing" a slice. I don't think it's a good
idea to deal with a slice by getting a hook-tendency club. Much better
to find out what's causing the slice (it's probably doing other bad
things to your game as well) and cure the disease rather than the
Go for a square face angle if you can.
- One of the more misunderstood
terms in golf club design is "gear effect". It is tossed around to the
extent that the naive think it's magic and the skeptical think it's
pure hype. Actually, it is real and explainable. For the explanation,
see the section on Impact.
- Clubs have two kinds of grooves:
Contrary to gross misinformation floating around on the subject, there
is absolutely nothing illegal about square grooves. (There was a
centered around Ping Eye 2 clubs made between 1985 and
1989, but it had to do with the spacing between the grooves, not the
fact that they were square.)
V-grooves, also known as "normal" or "traditional"
- Square grooves,
also known as "U-grooves".
The argument in favor of square
grooves is that they give more "bite" on the ball. That's also the
argument against them. Consider:
Before I leave the subject of the clubface treatment, I'd like to point
out a few studies that should be the last word on the subject.
- With more grip on the ball, the square grooves should be
able to impart more spin. This seems to be negligible in the case of
the clubface directly against the ball (as in the fairway or a tight
lie), but can be significant if grass gets between the clubface and the
ball. From the rough, square grooves can impart 25%-50% more spin.
(Note that from the fairway, even the complete absence of grooves
doesn't matter; the friction between ball and clubface is sufficient to
provide almost all the spin you can get.) For more on why it works this
way, see the section on
With more grip on the ball, the square grooves can be a surlyn
shredder. There's no doubt they rough up the ball's surface more than
V-grooves. Whether that matters to you is personal choice. Personally,
I like to be able to make my ball spin, and I have to play from the
rough more often than I would like. So I look for square grooves in my
own clubs. Your mileage may vary.
The first of these, reported in Cochran and Stobbs, compared grooved
clubs against clubs with perfectly smooth clubfaces. Their surprising
conclusion was that short irons give the same amount of spin to the
ball whether or not they have grooves, and whether or not their faces
are roughened. (Qualifiers: for five-irons and longer, grooves did
impart maybe 10% more spin; also, the experiment only applies to shots
from the fairway.) So the advertising hype about "milled faces" or
"soft copper faces with hard tungsten carbide particles" are hype and
The second study compared the
performance of square grooves with V-grooves. It was reported in Golf
Digest, December 1986. Their major conclusion supports the notion that
square grooves give an advantage from wet rough, but very little if any
advantage where the clubface itself strikes the ball dry and clean.
(The latter result supports the earlier study by Cochran and Stobbs.)
Here are some spin rates from the Golf Digest study:
| ||SPIN RATE|
| || ||V-Groove||Square Groove|
| || |
By the way, this
table also points up rather dramatically the
spin advantage of a 3-piece balata ball, regardless of the clubface
- If your swing plane is more
upright or flat than normal, you'll probably want a lie angle to match.
That's a simplistic view. In order to design and build a club with a
non-standard lie angle:
- Check section 3 on Club
Length; there is a strong interaction with lie angle.
If you intend to achieve the angle by bending the head, check the item
on clubhead materials in this section.
- The larger the loft angle, the
higher the flight of the ball. Also, generally, the shorter the shot.
While the trajectory is affected by the CG of the head and by the kick
point of the shaft, the loft angle is the single biggest determinant of
how high the ball will fly. (This assumes a well-matched shaft; if the
shaft is too soft, it will bend forward and add noticeable loft at
impact, resulting in a much higher trajectory.)
have reason to go non-standard, choose a set with standard lofts (e.g.-
5-iron loft of 28 degrees). (An exception is the driver, which I will
Beginners may want a little more loft,
to get the ball airborne. But remember that this problem may go away
soon after you begin the game, especially if you're reasonably
well-coordinated and athletic; do you really want to go club shopping
Heavy hitters with strong hand action
may want a "strong" loft (a lower loft angle), to get more distance and
keep the ball lower and out of the wind.
manufacturers are engaging in "distance wars", claiming that their
clubs hit the ball further. The major weapon in these wars is loft. The
club isn't inherently any better, but they've strengthened the loft for
more distance. The first offenders (possibly no longer the worst by the
time you read this) are Cobra for the irons and Callaway for the
Of course, this gain in distance is
phony. Consider, for instance, the Callaway "Heaven Wood", advertised
as a seven-wood with the shaft length of a five wood. But Callaway's
seven-wood has a loft of 20 degrees, while the "standard" five-wood has
21 degrees of loft. If you take a club with the loft of a 5-wood and
the shaft of a 5-wood and call it a "Heaven Wood", why should anyone be
surprised that it hits the ball like a 5-wood?
you want to change the loft angle by bending the head, check the item
on clubhead materials in this section.
- The "offset" of the clubhead is the amount by
which the leading edge (bottom) of the clubface is set behind the plane
of the front of the hosel. The more the offset, the more the clubhead
trails the shaft as it swings through the ball. Offsets range from zero
(typically in clubs for low-handicap golfers) to as much as 7mm in
"game improvement" clubs.
What the offset does is add a little
assurance that the hands are ahead of the ball at impact, a common
shortcoming of beginners. Since it delays the clubhead's striking the
ball, it has the beneficial (for beginners) effects of:
The term "progressive offset" refers to a set where the long irons are
offset more than the short irons. The theory is that most golfers who
need offset in order to square the clubhead need it more for the
longer, unlofted clubs.
- Increasing the likelihood that the clubface has closed to a
- Changing the effective loft at
impact, probably to increase the loft. (However, some experts seem to
disagree and believe the loft is decreased.)
If you gave an expert golfer whose
swing was grooved for zero-offset blades a seriously offset club, the
result might be snap-hooks and sky balls, because the club would then
be over-lofted and face-closed at impact. He/she doesn't need the help
of offset to get the hands "through the ball".
Bounce and Camber
- The "bounce" of the
sole is the angle the sole makes with the ground when the club is held
at a normal address. The term comes mostly from sand wedges, which have
a substantial positive angle on their flange that keeps them from
digging into the sand and burying.
The "camber" of the sole is
the curvature. There are two different kinds: heel-toe camber
(illustrated in the section on Club Length) and face-back camber. A
clubhead that has a lot of both kinds is frequently advertised as
having "four-way camber".
In the hope of reducing
confusion, I'm adopting some terminology I've seen used by Golfsmith.
The heel-toe curvature will henceforth be referred to as "rocker"
in these notes and my r.s.g. posts. The term "camber"
will be reserved for the face-back curvature.
with a negative bounce will tend to dig into the ground when it strikes
it. A zero or slightly positive bounce will skim along the ground.
Note that both swing styles are valid, and are taught by some following
of pros. The touring pros tend to take big divots with their irons and
sweep their fairway woods. Jack Nicklaus' tape and book "Golf My Way"
tends to encourage a sweeping swing with most clubs (even though that
point isn't made explicit).
- If your swing uses a downward strike of the ball, a negative
bounce means you'll take a "beaver pelt" divot with relatively little
- If your swing is a sweep that contacts
the ball at the bottom of the arc, a flat bounce may save a slightly
fat hit from becoming "play the divot, it went further than the ball".
A little face-back camber added to such a clubhead will reduce the
slowing of the clubhead from friction with the ground.
Now let's talk about rocker
(heel-toe camber, but I won't remind you again). I believe it's very
important, and greatly prefer more of it. Quoting from Golfsmith's
"Golf Clubs - Design and Repair":
soles of all clubs, both woods and irons, should have some contour from
heel to toe, so that when the sole touches the ground the contact point
will be directly under the sweet spot. This contour is particularly
important in the irons where divots are normally taken. With a flat
soled club, the slightest error in the lie angle would cause either the
toe or the heel to dig in at impact while the contoured sole has a
built in margin of error. Also, the contoured sole takes a narrower
divot, which permits the club to cut through the ground with less
effort." I agree with what they say about the irons.
However, I also find it makes a surprisingly large difference in woods,
even the driver. My most common mis-hit with a driver is scuffing the
ground before I hit the ball. Most drivers have a fairly flat sole
plate, so a corner (usually the heel for me) catches the ground and
turns the club; when I scuff a drive with a conventional-sole driver, I
usually hit a duck hook.
A few years ago, I experimented with
two new drivers:
I practice what I
preach with irons, too.
- Golfsmith's Big Gun
has accentuated rocker. Most of the times that I scuffed it, I got a
high draw instead of a duck hook; I lost a little distance, but usually
got away with a respectable drive.
- Acer's M160J
has a keel sole, the reductio ad absurdum of rocker. When I scuffed the
ground with that keel, it always dragged in the center of the clubhead,
without turning the club. You couldn't tell from the direction or
trajectory of the ball that I had scuffed; it just lost a little
- In the
past, I have used a sweeping swing that hits the ball without much
divot. My irons were Golfsmith Tour Model IV, with zero bounce (or
perhaps even slightly positive) and as accentuated a 4-way camber as
- This year, I have learned to hit down
on the ball. I have built myself a new set, with a sole better designed
to take a divot (less camber and no bounce).
- Sole Width
A narrower sole has less friction with the ground. However, if you hit
it fat, a narrower sole won't provide as much saving "skim" on the
surface; it'll tend to dig. In other words, if you are quite repeatable
with your swing and almost never hit it fat, you'll probably want a
narrow sole. A wider sole is a feature of game-improvement clubheads
for the less-precise golfer.
- Different designs of clubhead advertise their
Believe it or not, they're both telling the truth (as we hinted earlier
in the section on Physics).
- "Bigger sweet spot is
more forgiving." (Perimeter-weighted clubs, frequently referred to as
- "Puts the weight directly behind
the ball." (Blade or "muscle-back" clubs.)
If you almost always hit it on the
sweet spot, you'll appreciate the increased "feel" from a muscle-back
blade. If you're less precise, then your concern is minimizing the
damage from your off-center hits, and a cavity-back is called for.
There are a variety of patterns for distributing the weight in a
peripheral weighted club, but they probably don't have much to do with
which popular model the club looks like. The important variations to
look for are:
- A big bottom flange: low
CG helps get the ball airborne and makes the sweet spot taller. It is
more forgiving on "thin" hits.
- A reduced bottom
flange (concave like the Ping Eye 2, or even cutaway like the Ping
Zing): maximum heel-toe weighting to widen the sweet spot. It is more
forgiving on heel or toe shots.
- High square toe
(new Golfsmith designs) or extra metal at the top of the toe (Ping
Zing): supposed to help the clubhead "swing through" the ball and avoid
a slice. I don't have any intuition for why this should work, but I've
seen it in enough disparate places to give it some measure of credence.
However, I think there is something more easily explainable at work.
This moves the CG of the clubhead toward the toe, making it more
forgiving to toe hits. I believe that toe hits are a more common error
than heel hits, for non-expert golfers.
Semicircular "ridge" around the edge of the cavity (the 845, and a host
of imitators with three-digit numerical model numbers): I'm really not
sure what if anything this does, except to make it look like the
current "hot model".
- Relatively small cavity:
sometimes an indication of a cheap club (both price and quality). Have
they had so much trouble with the strength of their heads that they
kept the basic structure and performance of a blade but put in enough
cavity to look "fashionable"? I wouldn't get one unless I knew enough
about it to know this wasn't the case.
modified Aug 26, 2007
(modification incomplete; should revisit)