what is the pros and cons of each type??

here is my theory....

stiff:

good for power players, coz no energy is lost and all power goes into the birdie.
bad for beginner/intermediate players coz it is less forgiving and the feeling is more "dead".

flex:

good for beginner/intermediate coz the flex shaft actually gives the shuttle a "whip". more forgiving, the feeling is more lively.

i may be wrong, please refine it. this is definitely an interesting topic. along with and closely related to racket weight and balance.

What about the control of the birdie?
i mean, sometimes people say that the flexer the shaft, the better for defense and the stiffer it is, the better for offensive.
Isn't that what the Swing Power is trying to do with SX, SS, SR and SA?
to have different kinds of stiffness for difference kinds of play?

if by control, you mean how precise and delicate a shot the racket is better for, then i think stiff racket should give a better control.

and yeah, i think what you said is right. the flexier the shaft, the more whip you get and that's better for defense. and the stiffer the shaft, the more energy transfer and the better the attack.

What about those "long" shaft??
like the iso and the Ti versions??
what kind of difference do they make??
there must be pros and cons right?

Do you think Muscle power 100 is for defense? I read that it has flixible shaft.

i believe the long shaft increases head speed.

given the same rotational speed (angular velocity), a longer shaft will give the racket head a higher linear velocity. however, a longer shaft also means higher moment, that means it takes more time to bring the racket head to speed. the way to counter it is to make the racket lighter.

and i think that's what yonex did to the Iso900 when it was first released. the heaviest model SX is only 87g, a bit lighter than 2U rackets, which are rated at 90-94g.

Wouldn't it mean that the long length rackets are more for singles than for doubles??
Then why did Yonex make Swing Power that is long and also for doubles (SS, SA)

I think that length increase is supposed to increase the leverage of the swing. Supposed to be. Thats what Yonex said, but then again, you can't believe everything you hear. I mean 1 cm isn't gonna make much of a difference anyway.

I think that length increase is supposed to increase the leverage of the swing. Supposed to be. Thats what Yonex said, but then again, you can't believe everything you hear. I mean 1 cm isn't gonna make much of a difference anyway.

Notice that the length is added on to the stringed area. Making it bigger again. I think that its to increase the sweetsport again. But then again, 1 cm doesn't make much of a difference.