How far you hit your driver in golf is a function of two simple things: swing speed and quality of contact. You can always improve the quality of contact, but there's a clear ceiling in how fast you can swing your driver. That ceiling is a combination of your physical ability as a golfer but also the driver you're swinging.
For a lot of golfers, they think that by moving into a lighter driver shaft they'll be able to automatically pick up swing speed and clubhead speed, leading to longer drives. After all, shouldn't a golfer be able to see an almost direct correlation between having something lighter in total weight to swing and getting more speed?
PGA Tour winner Chris Stroud has seen this for himself in testing drivers. In this Secret Golf video, Stroud explains to Steve Elkington how he tested driver shafts to see for himself the effect of weight in a driver shaft.
Stroud said he went to a California facility and tested driver shafts on every part of the weight scale, from the range of 30-35 grams all the way up to some of the heaviest driver shafts in the 100-gram range. What Stroud found was something you'll likely find as well in a driver fitting: A lighter driver shaft does not necessarily mean a faster swing speed compared to a heavier shaft.
Stroud, who led the PGA Tour in smash factor (a ratio of ball speed to swing speed which cannot be greater than 1.52) for two seasons, said he realized the 70-gram driver shaft allowed him to maximize his swing speed. He didn't swing as fast going lighter.
Of course, shaft flex plays a part in this but, generally speaking, shaft flex is derived from weight.
Your ideal driver shaft weight will not be the same as that of a PGA Tour winner, and it might not even be the same with people of your same build, age, swing speed or ability. That's why it's key to finding the right shaft for your game.