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Understanding shaft "kickpoint" or "bend profile"

Discussion in 'Badminton Rackets / Equipment' started by visor, Apr 22, 2011.

  1. visor

    visor Regular Member

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    Understanding shaft stiffness/flex, and "kickpoint" or "bend profile"

    I was discussing shaft stiffness/flex and kickpoint on another thread,
    http://www.badmintoncentral.com/for...or-Super-Wave-37-(SW37)?p=1665478#post1665478
    but I thought I should start a new one specifically for it.

    So, after some reading up on "kickpoint" and "bend profile" which is more widely applied in golf shafts, I have a better understanding of how it applies to badminton rackets.

    In a nutshell, it doesn't provide more power either way whether high or low kick point, or stiff vs flex, but if you use the one that is matched to your swing then that is what will give you more power.

    It is your swing speed, acceleration, and release of your swing that ultimately determines whether it is better for you to use a high or low kick point, or flex vs stiff shaft.

    More specifically, it's all about having the racket face contact squarely with the bird being optimally timed at the point of strike for best power transfer.

    Hence, the advanced player with a fast, rapidly accelerated, delayed release (ie compact) swing will get better power from a stiff shaft with high kick point closer to the T joint. Because the swing is fast, the racket face has to move fast to contact squarely with the bird at strike.

    On the other hand, the beginner with a slower swing with no acceleration and early release (ie longer) swing will benefit from a flex shaft with low kick point closer to the handle. Of course these are just extremes and most people will fall into the spectrum between.

    If a fast swinger tries to use a flex shaft with low kickpoint, he'll overpower the shaft as the racket face will be lagging behind at point of strike, hence the bird will not be hit squarely. What the fast swinger will then consciously or subconsciously do is adapt his swing by "whipping" the racket face thru the bird so that the racket face has some more time to accelerate forward to strike the bird more squarely. However, the price he pays is that he will lose the immediacy and control of the stiffer shaft that he is used to using.


    **Also, advanced players, especially in doubles where speed and reaction is critical, will prefer stiffer balanced rackets because of lesser lag of the racket face, allowing shots to be repelled faster eg. drives, smashes, smash returns.


    **Another corollary arising out of this is that advanced players also benefit from higher tension as the stringbed is part of the racket face and shaft system. But that's another thread...



    What do you fellas think? :D


     
    #1 visor, Apr 22, 2011
    Last edited: Apr 23, 2011
  2. DinkAlot

    DinkAlot dcbadminton
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    Good post. Oh, please don't forget the biggest price one may pay for overflexing the shaft:

    [​IMG]
     
  3. cobalt

    cobalt Moderator

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    Apacs again. I'm surprised the handle didn't splinter as well... :D

    Very useful topic, Visor. :) This was (until now) a slightly neglected aspect of selection of a favourite weapon; lost in the excitement of dry weight, BP and string tension. Succinct explanation. :)
     
  4. allyjack110

    allyjack110 Regular Member

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    I fully understand the theory that a flexible shaft can help aid those with a slower swing speed with that little extra bit of power. However, would a racket with a flexible shaft 'rob' those of power with a natuarlly quick and explosive swing? My current racket(s) of choice is the HEAD Power Helix 7000 - a slightly head heavy racket with a flexible shaft. I really like the 7000 but cannot seem to generate the same power and energy I can with stiff-rated rackets, such as my current ArcSaber 10 or my old AT700 and NS9000 X, before I sold them.
     
    #4 allyjack110, Apr 23, 2011
    Last edited: Apr 23, 2011
  5. j4ckie

    j4ckie Regular Member

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    A flexible shaft can decrease your power - the release is more diffused than with a stiff shaft, so it limits how much acceleration is actually transferred to the shuttle. The stiffer the shaft, the quicker it 'unbends', and if timed and bent properly, it'll be much more powerful than a soft shaft.
     
  6. cobalt

    cobalt Moderator

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    It all depends on what type of player you are. That is always the first consideration when choosing your weapon.

    A player with a longer swing but not significant acceleration, (beginner? intermediate?) may prefer a bit flexy (bendy?? :D) shaft. The bendiness at some point of the swing will add acceleration to the momentum of the swing. The player may want, as Visor and other sages have pointed out, a racquet with a kick point more away than closer from the T-joint. That will allow the shaft to bend more easily and impart more momentum during the swing.

    So while it may be true in some cases that a flexible shaft may decrease your power, the corollary does not hold true that uh, a stiff shaft will enhance your power.

    A stiffer shaft needs more power (acceleration) to bend it in the first place. That is why it will be the choice of players who have the power, and can time the shot correctly, and can hit the bird square.
     
  7. cobalt

    cobalt Moderator

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    I need to find a new paradigm!! :( :D
     
  8. JukUx

    JukUx Regular Member

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    hey guys, i have this weird dilemma and i guess it falls under here hahaha.

    okay, so i've been playing with a lot of extra stiff rackets like the Ultra Pro and NS9900. I've been doing okay with it UNTIL i tried my girlfriend's arc 9 fl.
    When i started smashing with the arc 9 fl (flex shaft) my smashes seem more solid like theres more "boom" to it. which is great! so i thought maybe i need a more flex racket
    so when i play mix with her i don't have a flexy racket to use so i use back Ultra, although i don't get that "boom" my smash seems way more solid then smashing with the arc 9 fl.
    everything else is the same for me when using both rackets, its just the smash that feels different.
    I haven't play with my Ultra pro because i haven't strung it yet but i usually get more angle from the flex racket then the stiffer but this could be due to the fact that i've recently changed my form to the correct smash form or trying too

    heres my problem?
    so what flex is suited for me? I am a fast swinger now, no more slow swinging but yet i still generate a lot of controlled smashes with the arc 9 fl but i don't get that feeling when i smash with my ultra pro which idk how to put in words, it just feels solid. does this have anything to do with the BP? i use 295 and 299 for my two Ultras.
    should i be using mid stiff then? does mid stiff provide something in the middle for both?
    sorry if i am ranting, i just read this thought about what's above lol :)
     
  9. cobalt

    cobalt Moderator

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    Maybe it would help if Visor and/or Dinkalot or Jumpsmash can explain to us all how one can accurately locate the kick point...
     
  10. visor

    visor Regular Member

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    Lol Dink!

    Of all the people, I should've remembered that you understand this topic best! Especially the strong player overpowering a flex shaft. Those poor rackets never knew what hit them. :( :p

    I know you sometimes make racket suggestions to players when you observe and analyze their swing; I think perhaps you should start to offer a "custom fitting" consultation service for that and get paid for it! :)
     
    #10 visor, Apr 23, 2011
    Last edited: Apr 23, 2011
  11. visor

    visor Regular Member

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    I don't think at700 or as10 are stiff; their head heaviness causes the shaft to behave like a medium flex.

    Re a fast swinger using a flex shaft as in your case, I did provide a case scenario in my op above. In order to squarely hit the bird, you will learn/have to adapt your swing, specifically to "whip" the racket with your wrist/forearm so that the racket face will accelerate squarely into the bird at strike.
     
  12. visor

    visor Regular Member

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    Yes, but as I mentioned above in bold, one can adapt ones swing to whip the racket so that the racket accelerates into the bird. Of course, the price to pay is that there is more of a delay to strike because it'll take a bit more time to whip the lagging racket face forward, and this may also cause timing problems if the whipping action is not coordinated properly.

    If you get a chance to watch on YouTube, this is how LYD and JJS play with their flexy to medium stiff rackets, bs9 and bs10 respectively.
     
  13. j4ckie

    j4ckie Regular Member

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    I think the AS10 is stiff :D
    Maybe not extra stiff, but still stiff - especially compared to other 'stiff' rackets like the Z-Slash.
    The soft shaft will not only cause a timing problem, but also limit the power of shots, just like soft strings limit it. Imop, the best results can be achieved if tension and racket stiffness are at a similar level, i.e. stiff rackets -> high tension; soft rackets-> low or medium tension. Soft rackets and high tension feel weird in my experience (strung up a Wilson N9 with a 30,8lbs BG65Ti and it feels wrong).
    Back to the point - if the swing is quick enough, the soft shaft will be bent backwards quite a bit and will have to travel a long way to get back to the neutral position. This movement is slower than that of a stiffer shaft which was not bent so much, but accelerates faster.
     
  14. j4ckie

    j4ckie Regular Member

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    JJS uses a SIW35 :p
    But I agree, that's a way to use those rackets even if your swing action is sufficient to use a stiffer racket. LYD plays much at the front though where the mid-stiff BS09 probably gives his drives and kills a bit more punch than a stiff racket would.
     
  15. visor

    visor Regular Member

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    Doh! I knew that! :p

    Re LYD, I've always wondered why he uses such a mid flex racket. I'm sure he can handle a stiffer shaft like mx80 or bs10 and get more speed out of his smashes and drives. Perhaps the flex helps his defense better.
     
    #15 visor, Apr 23, 2011
    Last edited: Apr 23, 2011
  16. j4ckie

    j4ckie Regular Member

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    :D We all make mistakes :p
    I think it's mainly because of the drives, the defense is probably powerful enough from the shuttle speed...anyway, he's promoted to use the MX80, so maybe he'll use it for real soon...:rolleyes:
     
  17. visor

    visor Regular Member

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    Which also brings up the point that we as players are (hopefully!) improving our swing, timing, technique, power, and fitness as we gain more experience playing. Plus our swing will also fluctuate to some degree depending on our energy, alertness, fitness etc when we play.

    Hence our needs will change with time and this is only good news for racket manufacturers as we are always seeking for the "newest and best" racket for us. :)
     
  18. cobalt

    cobalt Moderator

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    Thank you for your question, Cobalt. Our Technical Support and other Specialists are at present busy with other Customer Service issues, and will get round to your question in a short while. In the meanwhile, please visit this site for further information and assistance:
    http://www.open2.net/diyscience/mangonel/index.html

    -From the KickPoint Technical Support Team.

    Ingest in jest...:D
     
  19. visor

    visor Regular Member

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    ^^^

    Lol! :D

    From my understanding, the kickpoint or bend profile is not a static but a dynamic measure. Meaning you can't just bend the racket between your two hands to figure it. You actually have to hit hard with it to feel the flex point.

    Having said that however, there are certain rackets with tapered shafts (technology borrowed from golf shaft design) that you can actually feel with your hand the separate joints of different diameter shafts as you run your fingers along the length of the shaft.

    Eg Panda Power rackets are designed with not just one but several kickpoints along the shaft, by joining 3 pieces of shafts of decreasing diameter from the handle to the T. Eg starting with something like 7.0mm diameter at the handle, to 6.7mm in the middle, to 6.5mm at the T. The idea of this design is that the shaft will flex more along the length of the thinner shaft and the flex profile can be designed to better take advantage of power and to be more suitable for a wider variety of swing styles and speeds.

    That's why the term bend profile is better to describe the shaft's dynamic behavior, rather than using kickpoint.
     
    #19 visor, Apr 23, 2011
    Last edited: Apr 23, 2011
  20. jump-smash

    jump-smash Regular Member

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    @visor
    hello ... I'm glad that you open a new thread here
    so we could discuss this interesting subject without being Out Of Topic ;)

    one thing about stiffness is that it is very difficult to measure without a proper machine
    how could we confirm it just by using feeling because it is relatively different for every person
    so it is hard to agree on the degree of stiffness even on the same racket
    what may feel flex for some could feel stiff for others

    furthermore the length of handle / cone and the shaft itself will contribute for more contradictions
    not to mention the location of the Kick Point / Bending Point and also Balance Point.
    the nearer the KP to the handle / cone it tends to feel more flex
    and the further the KP is to the T-Joint it will feel more stiff
    and also the more head heavy the racket it will make the shaft feel more flexible ...
     

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