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SteveI
01-02-2006, 09:47 AM
Swingweight "only" matters when you are swinging in a circle about some axis -- which is basically most of the time. Swingweight determines how fast you can accelerate the racquet. The swingweight of a racquet is an indication of how much torque you must apply to the racquet handle to get the racquet to swing. The value of the swingweight is determined by the amount and distribution of weight in the racquet. A low swingweight is very maneuverable. A high swingweight is less maneuverable but more powerful for a given swing speed. Swingweight is also a good indicator of how much weight is "behind" the ball at impact.

Of all the parameters discussed above, only the swingweight is not created equal in the sweetspot. The racquet with the highest swingweight will most likely be more powerful in the sweetspot during a normal swing about an axis like your wrist, elbow, or shoulder (stringbed stiffness being equal). That is because the ball will behave as if it collided with a heavier object and, hence, moves and rotates that object less.

The amount the racquet is accellerated when it is hit is related to how heavy the racquet behaves (not how heavy it actually is) at that point. This amount is known as the "effective weight," or "hitting weight," at the impact location. The faster the impact point accelerates backwards, the lighter must be the effective weight. The effective weight is indirectly related to the swingweight, and most of the time, swingweight can be used as a stand-in to predict results.*

Swingweight is therefore the only parameter that is intrinsically related to power at all impact locations. It is also the only variable that is related to maneuverability in almost all swings. And it is the only variable that can, under the right circumstance, cause an increase in power by being smaller (faster swing) or larger (more oomph behind the swing).

ollinger
01-02-2006, 01:14 PM
The equation defining swingweight implies that only rotation of the racquet around the wrist (not the elbow or shoulder) is described by swingweight. Hit a 1HBH with a firm (i.e relatively immobile) wrist and swingweight tells you next to nothing about racquet dynamics. Racquet stiffness and size of stringbed are likely better predictors of power (take a look at all the high-swingweight players' racquets around with relatively low power levels.) The equation for swingweight makes no accomodation for stiffness and head size and so is of limited value to explain the action of a racquet on a ball. This manifesto needs some refining.
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SteveI
01-02-2006, 03:01 PM
The equation defining swingweight implies that only rotation of the racquet around the wrist (not the elbow or shoulder) is described by swingweight. Hit a 1HBH with a firm (i.e relatively immobile) wrist and swingweight tells you next to nothing about racquet dynamics. Racquet stiffness and size of stringbed are likely better predictors of power (take a look at all the high-swingweight players' racquets around with relatively low power levels.) The equation for swingweight makes no accomodation for stiffness and head size and so is of limited value to explain the action of a racquet on a ball. This manifesto needs some refining.

Ollinger,

Got this off the racquettech website. Posted as a "Public Service Announcement". I saw it and it seemed to explain the concept in simple terms. The question is being asked all the time on this board.. so I posted this to help educate the masses :-) Thanks for reading the entire post and taking the time to comment.

Regards,
Steve

ChicagoJack
01-02-2006, 04:39 PM
Swingweight "only" matters when you are swinging in a circle about some axis -- which is basically most of the time. Swingweight determines how fast you can accelerate the racquet. The swingweight of a racquet is an indication of how much torque you must apply to the racquet handle to get the racquet to swing. The value of the swingweight is determined by the amount and distribution of weight in the racquet. A low swingweight is very maneuverable. A high swingweight is less maneuverable but more powerful for a given swing speed. Swingweight is also a good indicator of how much weight is "behind" the ball at impact.

Of all the parameters discussed above, only the swingweight is not created equal in the sweetspot. The racquet with the highest swingweight will most likely be more powerful in the sweetspot during a normal swing about an axis like your wrist, elbow, or shoulder (stringbed stiffness being equal). That is because the ball will behave as if it collided with a heavier object and, hence, moves and rotates that object less.

The amount the racquet is accellerated when it is hit is related to how heavy the racquet behaves (not how heavy it actually is) at that point. This amount is known as the "effective weight," or "hitting weight," at the impact location. The faster the impact point accelerates backwards, the lighter must be the effective weight. The effective weight is indirectly related to the swingweight, and most of the time, swingweight can be used as a stand-in to predict results.*

Swingweight is therefore the only parameter that is intrinsically related to power at all impact locations. It is also the only variable that is related to maneuverability in almost all swings. And it is the only variable that can, under the right circumstance, cause an increase in power by being smaller (faster swing) or larger (more oomph behind the swing).
Hi SteveI -

I appreciate the spirit in which you posted this. I'm a little hestitant to participate in this thread as this topic seems to always kick up quite a bit dust on this ranch. Personally, I'm with you for most of your top post, except for the first sentence and the last paragraph. I'm with Mojo for 95% of what he says, regarding SW--excepting the aerodynamics thing seems a little out of place to me. The only thing I know of that comes close to an all encompassing manifesto on the issues you are pointing to, was something that was published back in 2004. I can't say it any better than this guy can, so I'll just quote it directly.

[..]......................


FLEX
A stiff frame has a weak deflection when the string face is impacted by a ball. This weak deflection allows the stringbed to now interact more with the ball. Because strings are more resilient than the frame, they work harder when supported by a stiff hoop than with a flexible hoop. Because they are working harder, they also will experience a shorter string life (both durability and playability), but yield more power and, in many cases, more accuracy. However, they are not as forgiving on the arm, as the initial shock from an off-center hit is not absorbed in the frame as well as with a flexible model. Think of yourself in an egg-catching contest. You have been assigned to stand perfectly still and not move your hand backward with the impact of the egg in your hand while your opponent is allowed to move his hand with the impact of the egg to gradually slow it down. Which one of you wins this contest?

This brings us to the next point ...

WEIGHT
The more mass an object has, the more energy it can absorb. Imagine yourself driving a light compact car into an embankment at 30 mph, and then doing the same collision with a Sherman tank. Which vehicle folds up more? If you refer to Rod Cross's article "Racquet Power and the Ideal Racquet Weight" in the February 2004 issue of RSI, you will note how he calculates the ideal racquet weight by examining the weight of the player's hitting arm. It is well known that you don't need to work as hard with a heavier racquet to obtain ball speed, provided you can maneuver the frame into position for the ideal point of contact. In essence, you should use the heaviest racquet you can "comfortably" swing. Not only will it yield more power, it will also absorb more energy on impact.

However, you can't just wield a heavier racquet without regard to ...

BALANCE
Static balance, or "pick-up weight," allows you to either handle added weight or not. Three racquets all have 300 grams of weight. The first has 150 grams toward the handle, 75 grams in the throat area and 75 grams in the head. The second has 100 grams in the handle, 100 grams in the throat area and 100 grams in the head. The third has 75 grams in the handle, 75 grams in the throat area and 150 grams in the head. To put it simply, the first is headlight, the second is evenly balanced and the third is headheavy. The most powerful of these frames is the headheavy model and the least powerful is the headlight model. Think of the weighting of a hammer. The handle is light, the head is heavy and it packs a pretty good punch. Turn the hammer around, putting the head of the hammer in your hand, and try nailing with the handle. Tennis frames react in a similar fashion when weight (lead tape) is added.

The positioning of any added weight is critical to the performance of the racquet because it may severely affect the ...

SWINGWEIGHT
Swingweight, in simple terms, is what the racquet feels like in motion. A combination of too much overall weight and too much of the total weight concentrated toward the head of a racquet will yield a non-maneuverable frame. Baseline players tend to prefer higher swingweights, while serve-and-volleyers enjoy lower swingweights. Players with elbow problems are more comfortable with lower swingweights. Weight positioned at 6 and 12 o'clock will yield more power, but less stability, than weight at 3 and 9 o'clock. Racquets with too high a swingweight, although they will yield a powerful punch upon impact with the ball, take too much energy to maneuver into position, causing late contact and possible arm discomfort. Swingweights that are too low find the player consistently early on contact and prone to mis-hits, which may cause arm discomfort as well."

Excerpted from:
-Drew Sunderland, Untited States Racquet Stringers Association/RSI Magazine, May 2004

[..]

I'm not suggesting anybody is right or wrong here. The above statement just seems to bring the major concepts together in a cohesive way that make sense (to me at least) in both a theoretical and practical way.

Thanks again, SteveI best regards, to you.
-Jack