Finding the Flex

April 11, 2009

Frank Thomas is a former technical director of the United States Golf Association. He has written several books about golf equipment, the most recent being 'Just Hit It: Our Equipment and Our Game.'

If you have a question about golf equipment, e-mail him at [email protected].

Hi Frank,
I have always played stiff shafts since returning to the game of golf at age 32. Back in the early 90’s, when purchasing new clubs, I had my driver clubhead speed measured at 105 mph. Fast forward to 2008 and 50 years of age, with a reduced swing speed, and I am now considered borderline stiff shaft and advised to use stiff shafts in my new clubs.

No problem, I am hitting them well, but I sometimes feel that I am not getting my maximum distance easily. I would like to know, with a smooth tempo swing at approximately 96 mph, if a regular-shafted driver will hit the ball farther than one with a stiff shaft?


Your particular problem—not really a problem but a concern—is shared by many golfers. Shaft flex is one of the most important properties when it comes to fitting drivers or any other club.

The general rule of thumb is this: the faster your clubhead speed, the stiffer the shaft flex should be.

Golfers who swing at speeds between 80 and 95 miles per hour should begin with an R-Flex shaft and go up if necessary. If you find that the ball is going dead left with the R-flex on full hard swings, then and only then consider going to a stiff shaft.

Unfortunately there are no industry standards regarding shaft flex, so one manufacturer’s stiff shaft may be similar to another’s regular flex. This makes things complicated. Your best bet is to test a few shafts at a retail-store fitting booth. While far from a perfect fitting environment, it can help you find the best R-flex shaft for your game.

This is the time to use a launch monitor—which I sometimes call launch monsters because many golfers treat them like radar guns to simply measure swing speed—to demonstrate how swinging with rhythm with the correct flex will produce a better and more consistent result.

My prediction, going strictly by the information provided in your letter, is that a standard R-flex shaft will be best for your driver. Don’t worry about the kick point, special torque properties or extremely lightweight shafts until you are ready for major competition and want to tweak your trajectory. At your swing speed you should be driving the ball—assuming an average roll of 20 to 25 yards at sea level—about 240 yards. This is about 45 yards longer than the average golfer who shoots between 90 and 94 (based on test results and a pilot study at

Your launch conditions should be: 13-degree launch angle, about 2,400 to 3,000 rpm of ball spin, and about 140 mph ball speed when you make contact with the center of the clubface (more launch conditions are here).

One last thing, and this is probably my most important tip. Don’t get a driver longer than 45 inches. If you swing with tempo, you will find more fairways and increase your average distance with a shorter driver. You should even choke down if you have to, like Anthony Kim.

Good luck and happy holidays,