so i was wondering....why would someone want a really stiff/flexible racket. what are the advantages and disadvantages of both kinds. what stiffness is suited for what kind of player. it seems that my racket is rather flexible because when i wiggle it i can sort if see it bend.
There are two versions of stiffness in badminton racquets. One is material stiffness and the other is the stiffness of the shaft. I guess you are talking about the stiffness of the shaft. A badminton racquet, unlike a tennis racquet, must have resilience, which means shaft flexibility. Hold a tennis racquet with one hand on the top of the frame and with the other hand hold the handle, then try to bend the racquet. It will not bend, which means it is very stiff and has almost no resilience for the type of game that is badminton. A good badminton racquet should have the required resilience that fits the player and the quality of the racquet. An extremely flexible shaft has great resilience but, if it is not made of very high quality materials, it will have poor mechanical strength to withstand the stress and high impact loads of power shots. On the other hand very stiff racquets are mechanically very strong but slow and has poor resilience. With better materials now becoming available, you can have designs that will give you the more desirable racquet resilience without suffering from poor mechanical strength. In short, barring any shortcoming in mechanical strength, a more resilient racquet for easier handling, is better than a very stiff racquet, especially in the game of badminton where high-speed swing action is the norm.
In tennis, the more flexible a racquet it, the more power it absorbs and wastes in vibration. But, a flexible racquet has more "forgiveness" than a stiff racquet. With a stiff racquet, a player must hit the ball very cleanly in order to avoid errors and injury. A stiff racquet is more energy-efficient. The stiffer the racquet, the more shock is potentially transmitted to the player's body. Back when wooden racquets were used with gut string and players played with light-weight balls on grass, injuries were rare. All of those materials maximize safety but are less energy efficient. Grass is more flexible than concrete, and is therefore less accurate. Wood is more flexible than a high-quality graphite racquet, and is less accurate/sharp, and more energy-absorbing. Gut string is more resilient (less "dead"), than synthetic materials, and not only absorbs more energy, it repels more. Gut is softer than kevlar string but actually more energy efficient because of its resilience. So, it's safer for the player and provides more power efficiency. Some players feel gut's flexibility and resilience causes reduced accuracy. Sampras strung his 85" racquet with 18 gauge gut at 78 lbs in order to maximize control. Federer uses two strings, gut and a synthetic, because he says he likes the increased control provided by the addition of a synthetic. Synthetic strings have less repulsion/resilience than gut, but also can be stiffer. Resilience, or the "trampoline effect" causes energy coming into the strings-racquet from the bird/ball to be redirected back. "Flexibility" isn't the same thing as resilience. A flexible material can have low resilience, resulting in energy absorption but little repulsion. That's been my experience with the Yonex 75 MF Light (with stock string). Despite the claims I've read here that flexibility increases repulsion, that racquet absorbed energy and provided poor repulsion. A racquet like the TI-10, I believe, is marketed as having a combination of high stiffness and high repulsion. The stiffness, I think, keeps the racquet from absorbing a lot of energy and wasting it in vibration. The repulsion, I think, also keeps the racquet from wasting energy through absorption, instead causing it to go back into the bird. The end result that I believe high-end racquet makers are looking for is much like Pete Sampras' racquet's gut: stiff (high tension) for control, resilient for repulsion/efficiency. I don't have a degree in physics, so some of this, particularly the badminton stuff, is guesswork.
Actually a good badminton racquet design requires only three simple properties. They are lightweight, desirable resilience, and minimal air resistance. A basic assumption is that a racquet with these properties is mechanically strong enough to withstand the stress of a high-speed swing and high impact loads, especially from off-centre power shots. Alas, but in a cost-cutting world, some of these desirable properties are not being given enough attention. Lightweight requires very expensive materials. An 80g frame that has the same repulsion power of a 90g racquet will cost five times more. A more resilient racquet that has the same mechanical strength as a very stiff racquet will cost just as much if not more. A very crude way to find out if your racquet is fast is its weight, its beam circumference at the top half of the frame, and the amount and shape of its frontal area in the frame and throat/shaft.
to actually answer your question (generally): Stiff rackets = rewards a fast swing. Flexible racket = has a detrimental effect (as compared to a stiff racket) if you swing very fast, but rewards slower swings.
Actually lightweight and a reduced frontal frame area have the greatest effect on fast swing speed. In badminton racquets stiffness or high youngs modulus is more important in the materials that go to form the racquet frame and shaft. Stiffness of the shaft in a badminton racquet shouldn't be taken to too extreme, i.e. tennis racquet stiffness. All good badminton racquets, including the very stiff ones, do bend. This bending is the 'whip' which is essential in a badminton racquet but not in a tennis racquet. Of course you want the bend to be somewhere in the middle of the shaft and not at the throat. A badminton racquet that is as stiff as a tennis racquet, with no bend or 'whip', will not work. In the old days of 125g-145g racquets the shafts were very stiff, which were very good in the power department, but were rather slow in everything else. And you tire more easily.
I have no experience with the Karakal SL70. What is its weight, its racquet frame beam shape, at the top and bottom, and their circumferences? Also does it pack the same punch as say a 3U or 2U Mp99? If it does-and this test is the cruelest test (of lightweight racquets) for mechanical strength- then I can bet my bottom dollar that the materials of the SL70 must be exceptional. Cheap materials can never make a racquet that is light, fast, resilient, mechanically strong, and yet powerful. But cheap materials can make a slow, heavy, clumsy racquet, powerful. You just make it heavier, bulkier with large frontal and side surface areas, and they bring you power. The 50 year old 130g old Dunlop Maxply may be ancient but it has lots of power. I don't believe any modern racquet can have so much power for that one smash (but no follow-up).
http://www.amazon.com/gp/product/B0000WNDRA/104-1627602-8083159?v=glance&n=3375251 http://www.centralsports.co.uk/shop.php?page=detail&product=5692 reviews: http://www.badmintoncentral.com/reviews/showproduct.php/product/31/sort/2/cat/25/page/1 manufacturer’s site: http://www.karakal.com/products/badminton_products.html?cat=Racket
Can't really tell from these. However, super high modulus graphite is quite confusing. The industry has roughly three categories-carbon graphite, high modulus graphite or ultra high modulus graphite. And they are either PAN based or pitch based. But the real test is its power. Does it have the same punch as an MP99 or MP100? Also the lightness of the racquet is also due to its shorter length. If it were to be as long as an MP99 or MP100 it might not be under 80g. As a matter of fact there are some fake Chinese MP99 and AT700 that are below 80g because of their much shorter length.
it's this one: http://www.karakal.com/products/popup.html?code=KB350&colour=0000FF magnesium graphite, and standard length. It's 70grams unstrung.
