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Why Custom Fitting?

"I am confident that your professional approach to both clubfitting and clubmaking would benefit any golfer regardless of their skill level."
-- Patrick Therrien

"I hit just about every shot straight and solid"
-- Michael Larkin

Bulge and Roll

Roll, or the curve in a wood face from bottom-to-top, was added to clubfaces, along with bulge (horizontal heel-to-toe curving), over a century ago, when old Scottish clubmaking craftsmen discovered a horizontally curved face somehow helped reduce hooking and slicing. They did not know at the time why it worked, but they added it anyway. They also added roll, presuming that this feature, too, would help ball flight.

In fact, it sometimes does the opposite. We now know why toe and heel hits draw and fade, and how bulge helps. An off-centre hit causes the clubhead to twist around its centre of gravity. If this centre of gravity is far enough back from the face (true for woods but not irons), it adds spin to the ball in the opposite direction, like the meshing of two geared wheels. Thus, we call it the Gear Effect. By adding roll, clubmakers managed to start these toe- and heel-induced hooks and slices in the opposite directions, so the resulting bend in flight would bring the ball back to the centre of the fairway.

So, what about roll? Is there a vertical Gear Effect, and if so, do we want to reduce it? Well, it turns out that there is, but only if the head is big enough to allow club-to-ball contact far enough from the centre of gravity. As a consequence, it never came into play until the last 4-5 years, with the advent of grapefruit-sized driver heads. Researchers like Ralph Maltby and Tom Wishon spoke against the use of roll, saying it had no practical use. Recently, Wishon eliminated it almost entirely from his fairway woods, and removed it from the bottom half of his drivers. As a result, we'll likely see more of this practice, as other companies follow suit. Clubfitting specialist Henry Griffits has already done so.

But what about gear effect on large drivers? Well, recent testing on Trackman launch monitors has proved that a ball hit much higher up on a driver face does have slightly reduced spin. This is the vertical Gear Effect in action. Some players benefit from this, some don�t. At swing speeds of 100 mph or more, reduced spin can reduce friction around the ball in flight, allowing the ball's high speed to carry it farther. However, it doesn't work for slower ball speeds, because the ball speed isn't sufficient to keep it up in the air long enough to carry out with only minimal spin. The ball needs the aerodynamics of greater spin.

So reduced spin high on the face actually helps stronger-hitting players, but hurts performance at lower swing speeds and lower lofts. Fortunately, a bit of extra loft caused by roll on higher face hits helps average players to overcome the spin lost to the Gear Effect. This is much like bulge helping to correct Gear Effect hooks and slices. This extra loft helps stronger players less, but doesn't hurt them enough to warrant removing roll from high on the face. In fact, it allows better players to control trajectory for play into and with the wind, simply by changing tee height and face impact location.

Roll on the bottom of the face is another matter. Launch angle is vitally important in driver distance, and roll on the bottom of the face hurts launch angle, often badly. So there's no need for it. Good players rarely, if ever, hit that low on the face, so they need not fear picking up extra spin from the gear effect. And slower swingers can't afford to lose the launching loft, even with a trade for a small bit of extra spin. So it makes sense to eliminate roll on the bottom of the face. That's why you�re seeing some designs with less or no roll now, particularly on the bottom of the face of drivers. You'll see more of it in the years to come.


Based in Richmond Hill, Ontario, Sean Baines is a PCS-certified "Class A" clubmaker and the owner of Clubs That Fit. He is committed to providing quality, game-enhancing clubs and highly personalized service to golfers of all ages and skill levels.