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Dynamic Shaft Fitting Addendum

The Modern Guide To Shaft Fitting Now Online FREE!
Originally published in 1992, "The Modern Guide to Shaft Fitting" is the book that changed the way clubmakers (and for much of the golf industry) view golf shafts. The "Modern Guide to Shaft Fitting" verified what clubmaker's long suspected, that shaft specifications that were thought to be the same are not comparable at all. In 1989, Dynacraft Golf (now a Hireko brand), in a joint venture with the shaft company Apollo Golf, embarked on a project to test various shaft specifications under one single set of testing conditions. The tests would reveal variations in testing methods and labeling flex, torque, bend point, kick point, etc.

"The Modern Guide to Shaft Fitting" goes in-depth on each of the various shaft parameters, plus ties it all together using the most innovative shaft fitting system ever created, the Dynamic Shaft Fitting Index. The DSFI is a mathematical formula for shaft stiffness, based on the measured frequency and torque of a shaft, and then equates it into a player's swing speed. If you want to truly learn about shafts and shaft fitting, then second edition of "The Modern Guide to Shaft Fitting" is a must read. The latest edition is partially re-written to reflect on what we have learned the past eight years.

If you are having any problems downloading these files, please email us. We can also email the chapters to those that are having trouble downloading.

2019 Shaft Fitting Addendum

The 2019 version of the annual Hireko trademarked shaft testing project provides up-to-date measurements of thousands of shafts. Included are technical measurements of raw and cut weights, frequencies, torques, balance points and recommended swing speed ranges for each shaft. Included is an explanation of how to use the Dynamic Shaft Fitting Index (DSFI) in total club fitting applications. Written by Jeff Summitt.


For over 31 years, Hireko Golf has served the golf industry through its direct mail, website and retail channels. Hireko and Hireko's technical expertise has produced over a dozen nationally recognized publications and the Dynamic Shaft Fitting Index remains the dominant testing and development concept in shaft technology. Our brands include Acer, Hireko, Dynacraft, iBella, Synchron, Power Play, SK Fiber Karma. Hireko specializes in manufacturing and designing custom made golf clubs. For more information visit