gear effect (horizontal)
Gear effect is the term used to describe what happens to the club and ball when you have an off-center (CoG) strike. Watch the 1st video directly below to see how much the club head rotates when the ball is stuck off-center. Amazing video footage there!!
As you can see a ball struck on the heel of the club rotates the club face more closed, this rotation of the club head creates the “gear effect” and imparts a more positive spin axis (Slice) to the ball. Watch the 2nd video at 1 minute 34 seconds for a more detailed explanation from TrackMan University master Mark Anderson. A ball struck on the Toe of the club rotates the club face more open which imparts a more negative spin axis tilt (hook) to the ball. Watch the video opposite at 3 min 23 sec. The margin for error when the ball is struck off center is very small . Striking the ball just 0.14″ (1 golf ball dimple width) off-center could cause a 250 yard drive to curve 10 yards off-line and a 1/2″ off-center strike could cause a 250 yard drive to curve 35 yards off-line!! However the ball will not always slice when stuck on the heel and not always hook when stuck on the toe of the club. That will also depend on the club path and face angle at impact.
Correcting your swing and improving your accuracy with all clubs including Driver starts with the correct swing and ball flight analysis, I would advise golfers of all levels to book a session with a TrackMan University Master who are highly skilled at analyzing gear effect and other possible factors, this will help to pinpoint errors and help make the exact necessary adjustments to achieve your desired ball flight.