TBAR™ – Measurement and Method
By Carter Penley
As discussed in TBAR Part 2 – “The Art of Golf Shaft Measurement“, kick point is not the best measurement to determine a golf shafts ability to contribute to a golf clubs launch angle. For one thing, how is kick point measured? (See TBAR vs. Kickpoint Part 1).
At Penley, we recognized the need for a more precise and defined measurement for design purposes, and to allow a club maker or teaching professional to better fit their player with the proper golf shaft.
All flex measurements whether static or dynamic, are measured from the butt section of a golf shaft, with little or no attention being paid to the tip section. The results most of the time, can yield golf clubs of similar shaft flex, torque, head weight and swing weight, yet these golf clubs will have different feel, shot trajectory and/or dispersion; leaving you with the question, “what happened?” and “why”?
This problem became obvious back in 1999 during the first year of our PGA tour van operations. Although our tour representative and technician worked around the problem, I knew that if this was a problem for us, it was also a problem for the golf industry as a whole.
Having been in the composite golf shaft business for over twenty-five years and having experienced the above problem more than I had cared to count in my career, I was fairly confident that we could measure and correct for this deficiency.
Obviously something is different and that something was a way to accurately measure the relationship between the butt section and the tip section of a golf shaft. You can have similar butt flex measurements but with different tip flex measurements, because they are not measured during the design and or manufacturing process, they tend to be different in their relationship; and herein lies the problem.
It is this variable in tip section flex that contributes to launch angle, trajectory and feel (remember, kick point, ‘Article 1‘).
It is really the tip section flex in relationship to the butt section flex rather than some mythical bend/kick point.
To solve this problem, a series of data and measurements had to be generated to confirm our TBAR™ hypothesis, starting with the following:
1. What method do we use to measure TBAR™?
Static measurement was the best fit using a digital flex board utilizing a fixed load cell and LED read out panel.
2. How accurate should our TBAR™ measurement be?
Most digital load cells read out in Metric and US units. For our requirements Penley selected US because the data is in hundredths of a pound yielding the most accurate and greatest precision range.
3. How many measurement points would be required to develop the tip to butt aspect ratio?
A series of measurement points were selected and tested. These test points were always in pairs. Penley knew long span measurements were most accurate and generate more feel data. This reaffirmed Penley’s position that a golf shaft must be of a “one piece” design from tip to butt. A “one piece” golf shaft yields the best player feel, feed back, energy transfer and insures better distribution of stresses and mechanical loads throughout the golf shafts full length. (see “Long Drive Science” article by Carter Penley).
4. At which points along the length (‘X’ axis) of the golf shaft do we determine and administer the applied loads?
The effective span length is determined by analyzing the deflection of the golf shaft during deflection testing and a series of golf swings. Using this analysis the appropriate span and the corresponding position of its two end points were determined and fixed.
5. Should these measurements be taken in the droop plane or in the swing plane along the ‘X’ axis?
Penley defines only two planes for flex purposes: The droop plane and the swing plane (see ‘Shaft Spine” article by Carter Penley).
The droop plane is located parallel to the club face at the 12 o’clock position looking at the butt end and possesses the dominate spine reading, the swing plane is located perpendicular to the golf club face at the 3 o’clock position looking at the butt end and possesses the less dominant spine of the shafts dominant quadrant.Those of you who read the “Shaft Spine” article know that here at Penley we have established through player testing and mechanical analysis, in my opinion, the swing plane contributes most to club control for the player.
6. By which method do we present the data so that it is easily understood by a majority of the club builders, OEM’s and teaching professionals?
For engineering, design and calculation purposes a mathematical ratio expressed in proportional values/percentages is best; but for the everyday person a graphic is easiest to visualize and understanding of how to apply the information to help better fit a player with the best golf club for his level of play.
As we began to develop the measurements process and perfect the data, a tip to butt aspect ratio (TBAR™) pattern/algorithm began to evolve. We are now able to test the TBAR™ hypothesis in the laboratory and develop the process to include materials and geometric shape combinations and begin the full development and implementation of the TBAR™ system in the field of play.
Copyright © 2002, 2015 Carter Penley. All Rights Reserved
(all theories and analysis are still pertinent)