Stiff or Regular Flex: What Shaft to Play?

The shaft is the engine of the golf club, and selecting the right shaft flex is perhaps the most important aspect when choosing the right clubs for you. If you don’t have the correct flex, it can actually be detrimental to your golf swing and potentially hinder your ability to improve. The wrong shaft can force you to negatively compensate your swing at impact and lead to developing poor habits in your swing. 

If you want to improve your golf swing, you must know whether you should be playing a regular or stiff flex shaft. While the shaft material (steel, graphite, titanium, or some combination of these or other materials), and the weight of the shaft, are certainly part of the equation, most amateur players need to answer one basic question first—regular flex or stiff flex?

Should You Use Regular or Stiff Flex Shafts?

In general, golfers with driver swing speeds over 95 mph should play stiff flex shafts, and those under 95 mph should play regular flex. Shafts also come in extra stiff (105+ mph) and senior flex (under 85 mph). The higher the swing speed and the faster the clubhead acceleration at impact (tempo), the stiffer your shaft needs to be.

Which type of flex you need in the shaft primarily comes down to swing speed (how fast you swing the club) and tempo (smooth vs fast acceleration). Although swing speed isn’t the only determining factor, it’s the primary and good starting point. No matter how fast a player swings the club or how stiff, flexible, heavy, or light the club is, there will always be some degree of flex in the shaft in transition from the backswing through impact. The key is finding the right balance of swing speed and flex, giving you the most consistent ball striking and trajectory for a particular shot. 

The following chart outlines what flex is best based on swing speed and average distance. I included driver swing speed and 6-iron carry distance for comparison. Not everyone knows how fast their clubhead speed is on a driver swing, but most of us know how far we hit a 6-iron.

6-iron Carry Distance6-iron Swing SpeedDriver Swing SpeedShaft flex (all clubs)
< 130 yards60 – 70 mph75 – 85 mphSenior Flex
131 – 155 yards71 – 80 mph86 – 95 mphRegular Flex
156 – 175 yards81 – 90 mph96 – 105 mphStiff Flex
> 176 yards91 + mph105 + mphX-Stiff Flex
 

If you’re in between regular and stiff flex, I would err on the side of more stiff. You certainly don’t want a flimsy club, and it’s much better to have one that’s slightly too stiff than slightly too weak.

These are guidelines, and I suggest getting a professional club fitting to help fit the right shaft to your swing.

Related: Golf Swing Speed: Averages, How to Measure & Increase

What’s the Difference between Regular and Stiff Flex?

Stiff flex shafts are stiffer and less flexible than regular and senior rated flexes. Regular flex essentially means that the shaft is more flexible, allowing for more bend as you swing the club. Shaft manufacturers developed different flexibility levels to meet the needs of different golfer’s swing speed and tempo. 

In simple terms, “flex” is the extent to which a shaft bends at various points of the golf swing, primarily on the downswing through impact. As more force is applied on the shaft (i.e., the harder you swing it), the more the shaft will flex and “snap” through impact, giving the club more head speed through the ball and more distance along with it. Naturally, the slower you swing, the less flex is generated in the shaft.

What Happens if you Have the Wrong Flex?

If you have the wrong flex in your shaft for your particular swing characteristics, you will not strike the ball consistently and it will lead to decreased accuracy. 

Players with high swing speed already produce enough flex in the shaft and do not need the additional help that a regular flex shaft may provide. This shouldn’t come as a surprise—a flexible shaft will move the clubhead more throughout the downswing, which increases the likelihood of the clubface getting offline and not striking the ball squarely. 

Failing to hit the ball squarely on the clubface is what produces those dreaded but all-too-common, high slices and toe-hooks…or worse. On the other hand, a shaft that is too stiff for your swing can result in shots that are too low with little spin.

How Do I Know if my Flex is Regular or Stiff?

Not all regular and stiff shafts are created equally. One manufacturer’s stiff may be another one’s regular. However, there are some general guidelines when it comes to identifying flex ratings.

To determine what flex shaft you have, the label on your shaft will tell you. It will likely have a letter (referencing flex) and a number (weight in grams). Flex ratings are broken down as follows:

  • Senior Flex (S or A)
  • Regular Flex (R)
  • Stiff Flex (S)
  • Extra Stiff Flex (X)

Shaft Weight and Material

As referenced above, the shaft’s weight goes hand-in-hand with its flex rating, and the principles associated with more flex tend to be consistent with lighter shafts; the same goes for heavier shafts and stiffer flex. It is important to remember that what one manufacturer considers to be “regular” flex, another may consider being stiff. Thus, you should always consider a shaft’s weight in conjunction with the flex rating the manufacturer has provided. Generally, the heavier a shaft is, the stiffer (less flexible) it is. Naturally, a lighter shaft is going to be more flexible.

Shafts are made from many different materials or combinations thereof, but most amateurs’ decision comes down to just two—steel or graphite. Steel is the heavier of the two, and steel shafts will be stiffer than graphite.

Driver shafts typically weigh between 40 and 85 grams, with the average weight for men around 55-60 grams and 45-50 grams for ladies. Steel shaft irons weigh between 85 and 130 grams, with graphite shafts weighing as light as 55 grams. While a difference of 5 grams may seem minimal, it can significantly impact your swing (for better or worse) and how squarely the clubface strikes the ball. 

Despite conventional wisdom, and without getting into the physics of it all, a lighter shaft does not result in a higher swing speed simply by being lighter, just as a heavier shaft does not necessarily yield a slower swing speed. 

Nonetheless, a lighter shaft generally makes more sense for a player with a slower swing speed. A lighter shaft will typically be more flexible and will provide the benefits of more flexibility discussed above. In that same regard, a player with a higher swing speed is likely to benefit more from a heavier shaft to provide him or her with more control and accuracy.

Wrapping it Up and Heading to the Clubhouse

Flex is just one of many factors to consider in determining which club is best suited for your swing, but it is an important one that can significantly impact your ball striking. While there is no substitute for the assistance of a professional to determine the perfect balance of shaft flex, weight, length, and material in conjunction with your swing speed, determining where you likely fall on the swing speed spectrum is a key place to start for finding your ideal flex for any club.

Joe Morelli

Joe's been playing golf for 25 years, starting as a junior golfer in his early teens. He loves getting out on the links with his dad and friends -- whether an early weekend foursome or his weekday, afternoon league.

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