Flex
Flex describes how strongly the shaft of a club bends during the swing.
Shafts are divided into flex categories: ladies, senior (also called A or M), regular, stiff and extra stiff. The faster you swing, the stiffer the shaft may be. A shaft that is too soft bends too strongly at high speed, the strike point becomes restless and the shots scatter. A shaft that is too stiff gives too little, the ball starts flatter and shorter because you lose energy. Flex is thus, next to loft, one of the most important factors for your distance and directional stability.
In practice the clubhead speed decides the right category. An example: at the club fitting you hit a few balls with the driver, the radar measures 95 miles per hour. That is a classic case for regular. If your swing speed is under 85, you usually play longer and straighter with senior, because the shaft accelerates the ball better. Over 105 you need stiff, otherwise you lose control. The transitions are fluid; a ball flight test counts more than the label.
The most common misconception is prestige thinking: stiff strikes many players as a seal of quality, so they buy shafts that are too stiff and give away distance. The opposite is right — in doubt, the softer shaft is the better choice. Also note that the categories are not standardised: a regular shaft from one manufacturer can feel like a stiff from another. That is why, when buying, the test on the range counts, not the label.
FAQ
How do I find out which shaft flex suits me?
Decisive is your clubhead speed, not your feeling or your handicap. At the club fitting a radar measures how fast you swing — around 95 miles per hour speaks for regular, below that often for senior, clearly over 100 for stiff. The measured ball flight counts more than the label on the shaft.
Is a stiffer shaft automatically better for good players?
No, that is pure prestige thinking and costs you distance. A shaft that is too stiff gives too little, the ball starts flatter and shorter because you give away energy. In doubt, the softer shaft is the better choice — only one that is too soft makes the shots restless and scattered.
Can I rely on the manufacturer's flex label?
Only to a limited extent, because the categories ladies, senior, regular, stiff and extra stiff are not standardised. A regular shaft from one manufacturer can feel like a stiff from another. That is why when buying: test the club on the range and judge the ball flight, instead of trusting the label.