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Bending stiffness and the playability of badminton frames

Discussion in 'Badminton Stringing Techniques & Tools' started by stringtechno, Mar 24, 2013.

  1. stringtechno

    stringtechno Regular Member

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    Hi guys,

    Because our new tool can also measure the stiffness of the racquet we were talking about the importance of the stiffness of badminton racquets for their playability.

    RA-1-kl.jpg RA-2-kl.jpg

    For tennis the stiffness of the frame is very decisive for the playability of it.
    A stiffer racquet offers more power, because less energy is lost in bending it.
    A more flexible racquet offers a longer dwell time, the contact between the ball and the strings is longer so the player feels more control on his strokes.
    The stiffness of tennis racquets can be measured with a Babolat RDC and is shown in the RA value.

    We are quite convinced that the stiffness of a badminton is very decisive for its playability but this can be quite different from tennisracquets.

    We would like to know more:
    - If the stiffness is quite low in relation to the stiffness of the stringbed, this could offer a springy effect that offers more power. Is this so?
    - Or does a stiffer racquet offer more power for the same reason as for a tennisracquet.
    - Does any supplier of badminton racquets mention values for the stiffness of the frames that he supplies?

    Would like to hear your thoughts.
     
  2. yan.v

    yan.v Regular Member

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    Stiffness is quite important for badminton as well and every retailer and manufacturer mention the stiffness values of their racket.

    However, the relation between power and stiffness is not as simple as the relation you mentionned for tennis.

    In badminton, a player with less technique and/or power will find more power into flexible rackets because of the "springy" effet, or a whip like effect. Better players will find more power into stiffer rackets because of the better energy transfer into the shuttle. It is also the same for the stringbed stiffness. A player that uses a racket that is too stiff can somewhat compensate with less tension on their stringbed.

    The stiffness' effects on control are a bit different and many people say different things about it. In general though, stiff rackets (or strings) are considered to offer better control.
     
  3. stringtechno

    stringtechno Regular Member

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    HI Yan.V

    This is very useful information.
    I saw that the stiffness of the racquets is shown in stiff, medium …..etc


    Do you know if any absolute values are known?

    Our tool measures in kg per cm kg/cm, which means that if the stiffness is 20 you need 20 kg to bend the racquet down 1 cm.
    HI
     
  4. yan.v

    yan.v Regular Member

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    I don't know of any absolute values widely used by manufacturers.

    I do know that some companies like Black Knight use a rating value to indicate stiffness, but I don't know what they represent.

    Their ratings seem to be like this:

    < 82: Flexible
    82-85: Medium
    85-89: Stiff

    http://blackknight.ca/bk2013/

    I've seen other companies use different values, but I don't remember which ones on top of my head. Most companies just use: Very Flexible, Flexible, Medium, Stiff, Very Stiff or some variants of it.
     
  5. visor

    visor Regular Member

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    Some companies like SOTX use rating to 10, with a 20kg wt at mid shaft causing a deflection of the shaft.
    The deflection in mm being 7-10mm.

    7 being very stiff
    10 being veryflexible.
     
  6. kwun

    kwun Administrator

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    The part that is not clear to me about the sotx rating is where they support the shaft. Obviously the distance between the support points are critical to the measurement.
     
  7. visor

    visor Regular Member

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  8. vajrasattva

    vajrasattva Regular Member

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    is there a difference between stiffness and resilience? i.e. how fast it springs back to shape upon deformation?
     
  9. kwun

    kwun Administrator

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    it doesn't say where the support points are either. that's the crucial part. putting 20kg on the t-joint make no sense when it comes to measuring shaft stiffness. the only thing that make sense would be supporting at the handle, but 20kg on the handle, we are talking about 10cm+ of deflection.

    i bet whoever wrote that page was just told by some SOTX engineer/marketing, and never ever seen it done before.
     
  10. visor

    visor Regular Member

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  11. stringtechno

    stringtechno Regular Member

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    It is obvious that the position of the supports is very important. And if you want to measure that stiffness tells something about the playability you need one support at the position of the handle.
    We have positioned the support at the same position of the Babolat RDC, did anybody put a badminton racquet on that system.

    We know the relation between RA value and kg/cm.

    Of course we can do tests with badminton racquets with our tool as soon as it is ready.
     
  12. vajrasattva

    vajrasattva Regular Member

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    i've found that different racquets flex differently as well,

    i.e. on the i-slash or the gosen issen, it tends to flex more at the cone area of the handle, the gosen shiden, it flexes more towards the T joint.

    would have made more sense for measurements if shafts etc are proper full cylindrical rods, but in many cases they are tapered either upwards or downwards, so taking it at a single spot, does not necessarily represent the full playing feel
     
  13. kwun

    kwun Administrator

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    the idea for the measurement is very simple. anyone can DIY a machine like this in an afternoon.
     
  14. clawhammers

    clawhammers Regular Member

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  15. demolidor

    demolidor Regular Member

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    Thanks for the bump, now I can dump this pic here [​IMG] (since there are several thread about this in some shape or form)

    [​IMG]
     
    #15 demolidor, Jul 13, 2013
    Last edited: Jul 13, 2013
  16. visor

    visor Regular Member

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    ^ Interesting... what does that 230mm distance signify?
     
  17. demolidor

    demolidor Regular Member

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    The position on the shaft where the pressure is applied. From the bottom end of the shaft I (I presume), not the end of the handle (they don't even have a handle on them yet :D). BUT, putting a tape measure across, it looks more like it is from the end of the theoretical handle.
     
    #17 demolidor, Jul 13, 2013
    Last edited: Jul 13, 2013
  18. stringtechno

    stringtechno Regular Member

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    We are testing the production proto of our bending / stiffness tool at the moment and communicate that on the Dutch forum.

    We notice that the badminton world seems to split into 2 groups:
    - The ones who are not interested in any measuring and who want to keep everything as it was.
    - The ones who are interested in innovations and who want to do more measuring as support to their stringing qualities.
     

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