if I add 1/2in to a shaft how much will it change the flex and weight
If you add 1/2 inch to the length of a shaft and you do nothing to the head weight, the shaft flex stays the same. The swingweight will be heavier due to the increased length, which can make the club feel heavier. If you reduce head weight (if that’s and option) to maintain the swingweight the club was at the shorter length, then the shaft will be stiffer.
Britt Lindsey