Hi BCBF member, Don't ask me why I am not doing my work on Friday afternoon and posting on this wonderful forum. Here is my answer. The weather is too nice outside and it is Friday. I don't want to work! Don't ask me why I am not on a court and samshin birds away. We don't have a court opn right now! Anyway, back to the real business. What do you guys think about shaft stiffness index? Here is what we have right now. Yonex and many manufactures use the rating "Flexable", "Mid Stiff", "Stiff" and "Extra Stiff" to rate shaft stiffness (not body part). However, these are relative term. when MP100 first came out, it was most stiff racquet at that time. Until AT800-o came out, the king of stiffness goes to AT800-o later the NS9000-x took the #1 spot. However, these are just relative stiffness rating between different model at that time. I would like to propose a new rating index system that is not base on relative to other racquet model. Here are my 2 proposals. 1) Get a fixed weight (ie 20lb). Attach weight to a in-elastic string (ie piano wire made out of steel). Attach the string to a hook. (the hook shoud be able to hook on to the throat of shaft). The total length from the end of weight to the top of the hook shoud be about 30cm (no reason, just need to have some length to hook it up) Mount the racquet on a surface that is at lease 40cm high on the handle. (by a C or wood clamp). Measure the distance from the ground to the shaft with racquet only. Then hook the weight on to the throat of racquet. Measure the distance again. With the change of height and length of the shaft, we can calc the angle of the shaft bend. Use the angle as the angle index (lower the number, stiffer the shaft) Repeeat the same process for all racquet. 2) Get a crank head. Mount an in-elastic string to the crank head. attach a weight scale to the other end of the string. Attach another string to the other end of the scale. The attach a string to a hook. Mount the racquet on a surface and secures the handle with a C or wood clamp. Hook the string on the throat. Slowly crank the crank head and stop when top of the throat has move for 1 cm. Take the force (tension) measure. Use that as force index. repeat the same process for all racquet. Please post any idea or suggestion. Once we have some good idea, I will send some suggestions to Yonex to see if any stick. Thanks and have a nice weekend. PS, no blue pill joke.
The best person to talk to is Master NGP. He will tell right off the bat that certain Carlton models and the infamous CAB 22 ranke right up there as the stiffest pricks around .
Well, If you check the forum these kind of test has been tried.. I even tried that a few years ago.. But found the varying racket-lenght, shaft-lenghts, balances etc. affecting the results very much.. Also I have since then learned about dynamic stiffnes and static stiffness..and learned to treust my senses more So nowadays I really trust my senses more when testing than trying do-it-yourself measurements.. What really is needed is kind of the stiffness testing perofrmed for golf-shafts, where you get the shaft to osciallate and then measuers this.. Cheers, Twobeer P.S. Added from the wiki on measuirng golf-shafts stiffness: "Shaft deflection is measured by clamping the butt end, then placing a weight on the tip. The deflection of the tip is then measured. Frequency of the shaft is measured by clamping it securely at the butt and then oscillating it. The number of oscillations is measured (in cycles per minute). The higher the number of oscillations for a given length, the stiffer the shaft. Both are measures of the relative stiffness only at the butt end of the shaft. Another method used to measure shaft stiffness is Energy Inertia (EI) Curves. This is a three-point bending test that measures the load along the entire length of the shaft. However, feel goes beyond these measurements which will be explained later." D.S.
Good idea. I assume you need to attach some weight to the frame to make it easier to osciallate at higher mag? I did porpose the method #1 before. It was just not using angle as index. I never had time and equipment to carry it out.
I am not sure how the machines they use work exactly.. In Badminton It's even more komplicated as we also have a Stiffness issue with the head/frame.. Especially the torsion stiffness for off-center hits is interesting (theat Why Yonex have the T-joint, and other makers other solutions to acclomish this stifness.. The Mizuno Tetra-axial woven used in their high-end rackets are even more interesting (Se my review of the TX700 and 500 ) check out http://www.gws.hk/artman/publish/printer_25.php for example /T
unfortunately, badminton shaft is not sold separately. I would be happy if someone wanna donate his inventory of rackets and allow me to cut off the racket frame head off for the oscillation test. Also, i would need a machine to count the oscillation as well
Wrong! A panda tests stiffness or a racket shaft by hitting the racket and how hard the racket hits back.
Naaaw, you need new rackets that have not been used. Used rackets, all the shafts are soft, flexy and wobbly. The test would not be valid, at least not for measuring new rackets.
that is why i did what i did in the stiffness test. Badminton shaft is not high quality as those use in high end golf clubs. No need to be so precise as in golf since badminton shaft is often pushed beyond its yield flex point, therefore making it softer over time. Also, badminton racket is a multifunctional stick, unlike each golf club which is use for one specific range of performance.
I can tell you now, based on a stiffness, it's the Cab 22* and then everybody else. *I did try a Carlton racket that was stiffness as a board but didn't hit it enough to be able to give a valid comparison.
lots of factor determine flex. I think badminton racquets should incorporate the same flex determination methods as golf clubs. In golf, club flex is determined by, assuming all things equal: Head weight - heavier the club head, the more flexible the club will feel Shaft length - longer shaft feels more flexible Shaft flex rating - whatever the indicated flex There are other factors that determines flex, but badminton should at least begin to incorporate the above 3 important factors in flex determination. I believe currently the market only use what silentheart suggested, eg. put a specified force on the shaft and see how much is bends. However, for example, an AT700 shaft may only bend as much as a typical x-stiff shaft, hence rated x-stiff. however, cuz AT700 is very head heavy (ie. heavy head), therefore the x-stiff doesn't feel like an x-stiff.
Also take into consideration the shaft length. The shorter the shaft, the more stiff it will be, all else being equal. This is another reason why the Cab22 is so stiff.
the problem with measuring like this is that the stiffness of the racket can indeed be measured like that (placing the weight on the Tjoin, and clamping on the handle takes length, stiffness (and balancepoint) into account) measuring like this is however a static problem. The basics of which lie in what is essentially a see-saw model (but then instead of turning, flexing) But when you swing your racket, you have a dynamic problem. The difference is night and day, but since my colleges will start only in september, I'm hardly qualified to explain everything. (going for mechanical engineering) I just have one great example of a dynamic problem that only occures when things move: the Chinook ground resonance test. everythign stands still: nothing happens, blades move, everything resonates: devastation: http://www.youtube.com/watch?v=-LFLV47VAbI
Yeah, I rememberd that one. I agree with all you and other's point. Indeed I was thinking about using static measure to predict the dynamic situation. I thought it might be a good start. However, I agree that it will not be enough at this point. Thank you for all of your inputs.
Just go with the IPRS Test (Informal Panda Racket Stiffness) Test, it's free, easy to use and relatively accurate.
