TBAR™ – The Art of Golf Shaft Measurement Part 2

By Carter Penley

Through the years there has been a quest by many to define a golf shafts performance or the ability to fit a player by some simple magic black or white number or method. Some like to know how fast a player swings their club, or prefer a torque number, or a flex, or a shaft weight, or clubs swing weight, or a club length, or a shaft color, or… The fact of the matter is that there are many variables that contribute to fitting a player, some of which are more important than others: It is all a sea of grey. While no single measurement can define the total “performance aspect” of a golf shaft, I do believe there is a way to simplify and reduce the number of measurement variables.

After close to thirty years of designing carbon fiber (graphite) tubes parallel and tapered tubes, specifically golf shafts, I have come upon some interesting correlations in golf shaft measurement that can yield a more accurate method to define the “performance aspects” of a golf shaft that technically affords the club maker or teaching professional the advantage to better fit a player at most any level of play.

Historically golf shafts have been measured and the data has been presented in four specific areas.

They are:

1. TORQUE
2. WEIGHT
3. FLEX
4. KICK POINT

For design and manufacturing purposes there are many more measurements required, but for current discussion I will focus on these four, which are most commonly published and used.

TORQUE

TORQUE stands alone and is one measurement most commonly debated throughout the golf industry, although used frequently when fitting. Yet it is probably among one of the most inaccurate golf shaft measurements because there is no standard in the industry by which to compare the data. Quite frankly, not many club makers can measure for specific torque in a particular manufactures product and therefore most club makers rely on the golf shaft manufacturer’s torque number, accurate or inaccurate as it may be. (See ‘Torque‘ article, 1997 by C. Penley)

WEIGHT

WEIGHT is another stand alone measurement and agreed to by most all is the most accurate measurement (one gram is one gram), although again there is not a standard. Weight is specified as ‘X grams +/- X’ grams, but some manufactures include paint some with out paint, sometimes weight at full length or at some unknown cut to club length, also some shaft lengths can very from model to model and manufacturer to manufacture.

This is because club manufacturers measure club length differently; some measure club length from the club heel, the center of the sole plate and if it is a bore-thru not to mention some club manufactures have a specific club length different from their competitors.

 FLEX

FLEX is a measurement that has somewhat of a standard due to the fact that this measurement is easy to determine statically (flexboard using a weight and a limit shaft), and does not require a costly piece of equipment. On the other hand a dynamic measurement as performed on a frequency machine and does promote somewhat of a standard because of the wide acceptance of the old Brunswick frequency charts by many club makers (not withstanding inter-laminar opposing shear deformations). But even this form of dynamic measurement can be easily skewed due to the following:

1. At what position at the shaft butt do you clamp the shaft?
2. How much clamp pressure is used to clamp the shaft?
3. Do you use an actual club head and whose, blind bore or bore-thru?
4. Do you use a bob weight? Weight and hosel depth of bob weight?
5. Where is the bob weights center of mass in reference to the shaft tip?
6. Manufacturer and type of grip?

Again with no standard method, a comparable measurement is difficult to achieve.

Even with all the equipment, charts and graphs that are available to determine the flex range much of this data was developed as much as 20-70 years ago with steel shafts, and does not accurately reflect the standards required for today’s modern composite golf shaft.

 KICK (Bend) POINT

Last but not least. Most people have little or no idea of how this measurement is made much less its accuracy or its usefulness. This undoubtedly is the least understood measurement of all. I can tell you from experience that this measurement is probably the least useful for the fitting of a player. (See Part 1 ‘TBAR^tm vs. Kick (Bend) Point‘)

It is these last two measurements that I have a problem, specifically the latter.

Flex and kick point are measured and recorded as two separate measurements and I am of the opinion that these two measurements are closely related and should be combined to develop a new measurement. Standing alone they can be more of a hindrance than help when fitting a player. Combined they are a powerful fitting tool!

At Penley we have solved this problem and developed a new measuring system and related manufacturing design and process, called ‘Tip to Butt Aspect Ratio‘ (TBAR™) algorithm that we believe will help the golf industry change the way it has measured and fit players for the past 30 or more years. We believe the relationship between the butt section and tip section of the golf shaft is and should be a single measurement and is most important to the fitting of a player with a club (Amateur, PGA or Long drive) that enhances and improves their overall skills.

Read more about TBAR™ with Measurement and Method Part 3

Copyright © 2002, 2015 Carter Penley. All Rights Reserved
(all theories and analysis are still pertinent)

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