At the Core of COR (Coefficient of Restitution)

The former land speed world record holder Bobby Thompson once said, “Too much speed is never enough.” For golfers this could translate as “too much distance is never enough.” Golfers are always attentive when it comes to driving the ball further. And so it was of no surprise that the design of “hot drivers” gets a lot of press coverage.

These drivers are deemed hot because of their “coefficient of restitution” (COR) numbers. Put simply this is a measure of the speed of a ball departing the club face relative to the speed of the club. When a club arrives at the ball at 100 mph and the ball leaves the club face at 83 mph, the club measures a COR of .83. The USGA has now raised the allowable COR to .86.

Before you rush out to lay down a few Ben Franklins on a new high COR driver, give a moment to consider the following:

  • If your driver swing speed is less than 100 mph and you have an .83 COR driver, moving to a .86 you gain three to five yards

  • If your driver is several years old its COR could be in the .76-.80 range. Stepping up to a .86 could mean 10 yards or more. Now we’re talking one less club for your second shot and a tighter landing pattern.

  • However, if you don’t hit the “hot spot” (that portion of the club face with the high COR) the gain will be less.

  • Driving the ball further demands better accuracy.       Adding ten yards to a drive that would have stopped five paces short of the rough now means a drive that carries the rough. If you don’t hit it straight, you definitely don’t want to hit it far.

Bottom Line: Higher COR can mean longer drives. Before you buy a high COR driver, buy some “impact tape” ($2). With a strip of it on your driver, you’ll be able to see how often you are hitting the ball with the center of the club face. Improve center contacts and all of your present clubs will send your shots further and straighter.


Enjoy the thrill of hitting better shots!

Heartland Golf Schools

St. Louis

A Margin for Success

The Problem.

Why do many good players not hit a driver off every par 4 and par 5? Surely they aren't worried about overshooting the green. Why not aim at every pin? Isn't that where we want the ball to end up? We need to have a strategy that tells us when the most obvious shot is the wrong shot. We need to have a strategy to take on the course that builds in a "margin for success".

The Solution.

Here's a simple way do this. The next time you are at the practice tee, pick out a target for full swings with a wedge. Hit a dozen golf balls and note how far each of them land from the target (only count good swings). What was the average distance they landed from the target? For a typical golfer (16 handicap and above), they will find that their margin for success is about 8% of the distance to the target. So for a 100-yard shot their margin is 8 yards. Practically speaking, when they hit a wedge to a flag their good swings will land the ball within an 8 yard circle (24 feet) around the cup. For a 150 yard shot the circle grows to 36 feet.

Take Away.

So when we are getting ready to pick our target, draw the appropriate circle around it. If the flag is tucked against one side of the green and the 24-foot circle encompasses a green-side bunker, that would not be a flag we would shoot at. The same reasoning goes for your tee shot.

If your not sure of the percentage of margin your game deserves, start with 8% and adjust after a round or two. Always go for the best target unless trouble lies within your "margin for success".

Enjoy the thrill of hitting better shots!
Heartland Golf Schools
St. Louis