Jeff Summitt Discusses The Ins and Outs of Gear Effect  Have you
ever wondered why the faces on drivers, fairway woods and even
some hybrids are not flat like an iron?  Well if you haven’t
noticed, take a quick look. There is a certain amount of
curvature to the face of a club which is considered a positive
design feature.  Why? Before we get to that point, let us
understand the anatomy of the club first along with some quick
definitions.  There are typically two radii on the face.  The
first one shown is called horizontal bulge which is the
curvature in the horizontal plane extending from the heel to the
toe.  The second radius is vertical roll, which the curvature is
in the vertical plane from the sole of the club to the topline.
The units of measurement are expressed in inches its radius.  A
popular dimension amongst drivers and fairways are produced with
a 10 inch bulge and 10 inch roll.  To provide an explanation,
imagine a circle 20 inches in diameter (10 inch radius). The arc
of that circle would have