When you lengthen or shorten a club and do nothing to the head weight, a shaft will maintain it’s flex characteristics, but will feel different. A shorter club generally will feel lighter and firmer to some and a longer club will feel heavier and softer. It’s just that the shaft actually stays on the same flex line with regards to frequency. If you add weight back to the shorter club for swing weight purposes, the shaft will play more flexible. for every swing weight you add, it gets 1 cycle softer. There are 10 cycles per full flex, so you can do the math. If you added 20 grams back to the head weight, then that would be 10 swing weight points and that would be a full flex.
Britt Lindsey
Thank you