The shaft is the part of the club that connects to the clubhead. It is located in the middle of the club, between the grip and the head. The grip covers the top part of the shaft whereas the bottom end is inserted into the clubhead through the hosel.
Variety of Flex Levels
Golfers with fast swing speeds will favor stiff shafts or even extra stiff in some instances. Golfers with average swing speeds will favor regular shafts and finally those with slower will opt for flexible, or senior flex ones.
A stiff shaft will tend to send the ball on a lower flight path and a flexible (or senior) shaft will send it on a higher flight patch, all other things being equal.
Function of the Shaft
The distance between the golfer and the ball – through the shaft – is what allows for the multiplication of the force onto the golf ball.
Generally speaking, the longer the shaft, the bigger the lever and the longer distance a ball could travel.
This means that they are wider at the top near the grip and progressively become smaller in diameter as they approach the clubhead.
While this progression is completely smooth on graphite shafts, the reduction in width is visible in the metal variety through clear reductions in diameters at regular intervals.
Variety of Kick Points
The kick point – or bend profile – refers to the region of the shaft where it bends the most.
A shaft with a high kick point will bend most at a higher point than the middle and should help send the ball on a lower ball flight. Conversely, one with a low kick point will bend most below the middle of the shaft and will help send the ball on a higher ball flight.
Shafts also vary in lengths; the driver usually has the longest and the putter the shortest. For the clubs situated in the middle of those, generally, the shaft length will decrease as the loft will increase. So for example, a 5-iron will be a bit longer than a 6-iron, which will be longer than a 7-iron, and so on.
As the golfer gets nearer to the ball so does his ability to control where the ball will go, all other things being equal. Among other factors, this explains why a golfer will usually be more precise using a 9-iron – which has a shorter shaft – than with a driver – which as the longest.
Additionally, the length of a shaft can be fine tuned if a golfer decides to buy custom fitted clubs.
For example, a tall golfer – say 6’3” – may find it more comfortable to use clubs whose shafts are 0.5” to 1” longer than the default sizes.
Conversely, a golfer with an extremely fast swing speed may find he is able to better control his driver when it is fitted with a shaft that is shorter than usual. A shorter shaft would position him closer to the ball for more control, at the cost of slightly less leverage and ultimately less distance.