Many golfers believe that as long as the new shaft has the same butt frequency as their current shaft, the shafts stiffness will match their swing.
Unfortunately, there’s much more to the stiffness design, performance and feel of a shaft than a single butt frequency measurement. As a result, it’s actually quite rare for two shafts to have the same butt frequency as well as the same stiffness design over the full length of the shaft.
The following table illustrates an example of this statement: let’s take a look at the full length stiffness design of two shafts for drivers and woods, both made by the same company, using the Bend Profile software to create a comparison:
The two shafts have the same 180cpm butt frequency measurement and, if done with a 205g tip weight, would both have the frequency measurement of 254 cpm. So we see here that if two shafts are measured only for the butt frequency, we will be led to believe that they have the same flex, or stiffness of design.
However, when we take a closer look we can see that, even though they might have the same butt frequency measurement, they are completely different in terms of their overall stiffness design. This means they will result in completely different stiffness performance and feel. This assumption also affects the selection of iron shafts, as we can see in the chart below.
Based on the information, we can see that if a golfer were to play both these shafts the Rombax S would feel like the ProLaunch Red S, even though they have the same butt frequency:
As we can see, if a golfer is serious about their shaft selection, we need to forget about judging shafts based on their butt frequency. Let’s take a look at another pait of shafts, a Cleveland Gold 60 S and the FUjikura Blue 004-R:
We can see the relative stiffness measurements after the butt frequency measurement. The 2 / 3 / 5 differences in frequency for the 26”, 21” and 16” positions on the shaft are so small that there is essentially no difference in stiffness between the two shafts.
Essentially shaft stiffness selection needs to be made not just on the basis of the butt frequency, but based on the stiffness of the full length of the shaft. So when you hit a shot with a club that you know has the same frequency but feels or performs differently, now you know why.