# Thread: 2003 Yonex rackets measurements

1. in a way i do agree with u. sometimes pll differenciate stiffness of the shaft instead of the frame.

2. I don’t where to begin to reply. Your last post contains so many flaws and disconnected illogic that may snow someone who don’t know material mechanics and physics. To clarify my point, allow me to dissect your last post. Your quotes are in between asterisk (*).

1. * I think there is some confusion and misunderstanding about a racquet's stiffness or flex as they relate to power.* I think you are the one who is confused and misunderstood on my chart of racket stiffness.
2. *Measuring a racquet's stiffness by bending it does not tell you its flex.* I say it does. If not, can you provide me a better and more reliable stiffness test that doesn’t cost thousands of dollars.
3. *It merely tells you the racquet will give you added whip if it bends uniformly, which it should if you are looking for a little more whip.* Wrong again, stiffness tell us more than just ‘whip’, which I find your term ‘whip’ is so general and vague. Define your term ‘whip’. I can get more whip just from striking the shuttle harder, independent of racket stiffness. All people are looking for more whip. So, are your saying beginners should get the stiffest racket because it give the most whip?
4. * The flex of a racquet is primarily a stiffness test on the frame* Hahahaha, this is so (censored)…well, what can I say. Tell that to a golfer, stiffness is all on the club head, hahahaha. So, if someone want a whippy racket, what kind of frame should he get? LOL.
5. * Comparing a mildly stiff shaft with a very stiff shaft by bending tells you nothing, as both will bend.* LOL, yes, we all know everything bends, including concrete. So you are saying bending the shaft doesn’t tell us anything about the racket except they just bend? Even a little kid can answer this one.
6. *Racquets that are rated as not stiff will have their frame flex more, and lose energy* How about a racket with Aluminum frame and 1st generation graphite shaft. The Al frame won’t flex more just because the flexy shaft flexes more. What make you think flexiness relates to degree of energy lost?
7. * You cannot see the difference in frame flex with your eyes : there is a way to measure it in the plant.* LOL, sure I can see it, that’s how I measure stiffness, with length, width, and depth measurements, all read by my eyes. I bet that’s how yonex measures stiffness too. If I use my 2 hands and bend a racket, I can see the shaft bending in a curvature, amazing huh?

Your analogy of steel vs Al rim make no sense to me in relating to racket stiffness and performance. Beside, Al rim with same weight as steel must have to be a bigger rim. Are you saying yonex should use aluminum shaft? Yonex had use steel shaft before. On pots and pans, you are so out of it. Hotspots have nothing to do with pot’s stiffness. It have to do with material heat conductivity constant and thickness.

8. * In other words, you have to take the manufacturer's word on it's racquet flex stiffness.* WRONG. Manufacturer’s word is just a guidance. Case in point. AT700 is rated extra stiff by yonex. My tangible test show it is NOT even just stiff, more like medium flex, similar to mp27 and a tad stiffer than cab20MS. My claim is back with number liking me saying the temperature is 27.3 degree Celsius, not like saying it's extra hot in yonex terminology. Furthermore, feedback from many AT700 users says AT700 IS NOT STIFF at all.

3. Racquet flex is not a test of shaft stiffness. It is measured on the Babolat RDC as flex number, using a 25kg load on the string bed, repeat, string bed, of the frame. The shaft has no string bed to test, and it is not directly in contact with the strings like the frame is, where the greatest impact and flex occur.
Yes, older racquets made from steel and aluminum did flex more, despite their apparent 'rigidity'. Just like steel car wheels and stainless steel pots. But that is another story.
Yes, on the shaft: you can have two racquets of the same material and same flex, with one having a longer shaft than the other but the overall length of both is the same, both racquets will be rated as equal in flex stiffness. However, the longer shaft will have more 'bend' and, consequently, will have more whip. Testing for racquet whip is one very important test you should do when choosing a racquet from the same brand and model.

4. Originally posted by taneepak
Racquet flex is not a test of shaft stiffness. It is measured on the Babolat RDC as flex number, using a 25kg load on the string bed, repeat, string bed, of the frame. The shaft has no string bed to test, and it is not directly in contact with the strings like the frame is, where the greatest impact and flex occur.
Yes, older racquets made from steel and aluminum did flex more, despite their apparent 'rigidity'. Just like steel car wheels and stainless steel pots. But that is another story.
Yes, on the shaft: you can have two racquets of the same material and same flex, with one having a longer shaft than the other but the overall length of both is the same, both racquets will be rated as equal in flex stiffness. However, the longer shaft will have more 'bend' and, consequently, will have more whip. Testing for racquet whip is one very important test you should do when choosing a racquet from the same brand and model.

LOLOL. I dare you put a 25kg (55 lbs) load on a badminton racket string bed to test frame flex. I repeat, i dare you. Now i realize the cause of all the flawed statements in your past posts. I concluded that you have basically taken what you have read or heard (from other uninformed friends) about TENNIS and transferred directly to badminton without understanding the underlying principles of science and its limitation. (It's like a 5th grader briefly read a university science book and declare that he can skip junior and high school science). In this case, the babolat RDC test and number are designed for tennis racket. You see, in today's tennis rackets, the shaft is a truss, built to resist flexing. All the flexing and other racket characteristic are defined by the frame. THIS IS NOT THE CASE FOR BADMINTON RACKET.

your statement *like the frame is, where the greatest impact and flex occur* is for tennis racket. In badminton, greatest flex occurs at the shaft piece AND we want minimum flexing from the frame.

It is obvious (to me) that you have also misunderstood why performance drivers prefer Al or Mag rims over steels. Yes, that's another story. It's enough schooling for today.

5. But what does the Babolat RDC measure?
Is the racquet handle clamped and then the amount the head moves is measured?
Or what? Does it make a difference what the string tension is?

But then, cooler continues to not give us details of exactly how he made his measurements. I think as far as we got was that he clamped the handle and then bent the racquet.
How did you bend it. Apply a weight? Where did you attach it? At the throat, middle of the strings, top of the racquet?
Where did you measure the deviation? At the throat or head of the racquet, or where?
You give us a relative stiffness figure based on the total length of the racquet, which is probably only valid if you bent the entire length of the racquet. I would have expected the length to be the distance between the clamp and the point at which the force is applied.

It might sound like picking at little details, but you are giving numbers to several decimal places. Sorry if this comes across as harsh, but I am interested in the details.

6. The Babolat RDC (racquet Diagnostic Center) machine to test a racquet's flex is like a giant racquet stringing machine, holding the racquet frame with clamps or grips. A load is then put onto the string bed to measure its deflection. It is French made. There is another similar diagnostic machine that is swiss made which the industry uses. I am not sure what Yonex is using, as they could be using their own; but I have sent an inquiry to Yonex Japan for more details.

7. Originally posted by taneepak
Racquet flex is not a test of shaft stiffness. It is measured on the Babolat RDC as flex number, using a 25kg load on the string bed, repeat, string bed, of the frame. The shaft has no string bed to test, and it is not directly in contact with the strings like the frame is, where the greatest impact and flex occur.
Obvious you don't know what that above test is for. I presented racket stiffness data in my chart. You are talking about string bed stiffness, taken from the context of tennis racket. Read this and learn

The RDC is a high tech instrument capable of taking precision measurements of several racquet and string specifications. It can measure weight, balance, stiffness, string bed stiffness, and a particularly critical characteristic known as “swing weight”.

example of string bed stiffness tests

BENCH TESTING
The two coils tested measured 40'5". The diameter ranged from 1.29 mm to 1.32 mm. Stringbed stiffness of 81 RDC units was recorded immediately after stringing at 60 pounds in a Wilson Pro Staff 6.1 95 (16 x 18 pattern) on a continuous pull machine. After 24 hours (no playing), stringbed stiffness measured 74 units, representing an 8.64% tension loss. Our control string, Prince Synthetic Gut Original Gold 16, measured 80 RDC units immediately after stringing and 73 RDC units after 24 hours, representing an 8.75% tension loss.

It has nothing to do with frame stiffness. It measures string bed tension. We BF here already know about string tension loss after stringing. We just havent measure them like in tennis. There are more money in tennis and golf, that is why those sports can go afford to tackle more parameters of that sports.

I have made attempt to measure other racket parameters like balance (tippyness), stiffness (relative stiffness), swing weight (relative moment) and weight like what the rdc machine can do, all before i even know about this babalot machine.

8. ## Interesting...

...I am not going to jump into the string bed stiffness vs shaft stiffness debate.

This is for cooler. Since you have measured the flex of the Yonex racquets, are you able to do the same test for other manufacturers (e.g. Winex, Babolate, BK, etc.) using the same baseline racquet (Cab 20MS)?

9. Yes i can. I have said before my tests are repeatable and consistent.
I can also re-normalize all values back to a orginal cab 20 too if i have one although we could debate on which cab 20 to use (gold vs green cap, U, 2U, 3U, red, blue or orange version) as not many player is lucky enough to try the 'true' original cab20. IMO, the 'gold standard' should be a gold cap cab 20 with 2UG4 grip, preferrably a new one No SP vs CD vs JP vs HK etc variables to deal with.

To understand each racket behavior(without really touching it), one must able to mentally combine, imo, these 3 key parameters, stiffness, balance and swing moment. Weight, string tension, string gauge and grip size are important too but maybe too many parameters to juggle at one time for some.

10. The racquet's flex or frame stiffness, not the string bed, is measured on the Babolat RDC machine as flex numbers. It is not tension-loss numbers. The RDC flex numbers are what they say.

Page 8 of 22 First 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Last

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•