Patent ID: 6916251

Claim:
A golf club shaft set comprising a plurality of golf club shafts to constitute a golf club set, wherein the plurality of golf club shafts include a group of at least three golf club shafts, and, when all of the golf club shafts in the group are denoted by continuous natural numbers X starting at 1 in order of decreasing length of the golf club shaft from the longest length and a ratio of frequency calculated from a frequency per unit time as a numerator, the frequency being measured by vibrating a tip portion of the golf club shaft in a state that a rear end portion of the golf club shaft is fastened, and a frequency per unit time as a denominator, the frequency being measured by vibrating the rear end portion of the golf club shaft in a state that the tip portion of the golf club shaft is fastened, is denoted by Z, the ratio Z of frequencies is determined so that an estimated error to a regression line is 0.05 or less, when a distribution of the ratio Z of frequencies to the natural number X in all of the golf club shafts in the group is fitted on the regression line.