Golf Shaft EI Measuring Instrument

Golf Shaft EI Instrument

By Russ Ryden, A Golf Digest America’s 100 Best Clubfitter
Fit2Score, Dallas Fort Worth, Texas

Several years ago I learned the term EI from engineers in the business of designing shafts. The instrument most used was in the $10K+ range, making if not affordable to most. Not even all shaft companies have these instruments. It took about 2 years to come up with the original affordable EI measuring instrument design. This shaft review site shows measurements taken with the Fit2Score instrument.

After many years of use, I decided to redesign and improve the instrument. The improved Fit2Score EI shaft measuring instrument is now available. This animation show it cycling on a shaft.


The gauge is re-positioned to improve accuracy and repeat-ability on measurements. Positioning pins are incorporated into a manufactured weight. Most of the original instruments have been upgrade with these assemblies. The newly designed self centering shaft support maintains the radius of the earlier design while eliminating guides to center the shaft. The shaft naturally ‘falls’ to the bottom of the curve making readings faster and repeatable.

A hoop stiffness measuring fixture has been designed. It centers the shaft under the press and uses the 11kg weight and .0001 gauge to measure hoop stiffness. The updated database structure includes fields for hoop stiffness readings along the length of the shaft. This pulls aside another veil of understanding the golf shaft, giving the club maker a method to evaluate marketing claims.

The instrument is now available for $3000. Excel based spreadsheets are included for gathering and analyzing profiles of shafts. Owners have the option of subscribing the the historical knowledge base that is at the core of the reviews on this site. Contact if you are interested in this essential club making instrument.