If have two identical iron shafts, let’s say trimmed for a 7 iron, and one is 1/2” longer, would there be any difference in stiffness if installed in the same head?
Britt Lindsey Answered question May 18, 2023
If have two identical iron shafts, let’s say trimmed for a 7 iron, and one is 1/2” longer, would there be any difference in stiffness if installed in the same head?
If you do nothing to the headweight, a shafts flex does not change if you make it longer. The frequency number changes, the feel changes, but the actual flexural properties do not change. It will stay on the same flex slope on a traditional frequency chart. If you lengthen a club and then want to reduce headweight (assuming you could) to maintain a swing weight, then the shaft would actually play stiffer at the longer length. Conversely, if you wanted to shorten the club by 1/2″ and then add weight back to the head to maintain a swing weight, the shaft would then play more flexible. Of course this assumes any length alterations are coming from the butt end, not the tip end.
Britt Lindsey
there will be a difference in butt stiffness of 5cpm (the shorter shaft will be stiffer)
I measured a 4 Iron shaft with a 255 gram weight to verify the above.
Note this is only the butt stiffness, which in my opinion doesn’t mean much.
A shaft is profiled throughout it length at various points. This is what will help determine, tip soft/stiff, launch trajectory, kick point….
I use Wishon’s method where he measures stiffness from the tip at 5″ intervals beginning at 11 inches, through the length of the shaft. So, in the case above 11″ from the tip, 16″ from the tip, 21″ from the tip…etc. the cpm at each point remains the same as it’s referenced to the tip.
The procedure Golfworks uses can be found at this link: chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://store-k9nvqai7wz.mybigcommerce.com/content/PDFs/Tool_Instructions/MA2014.pdf