Customizing and effect on Swingweight

LuisM

New User
I understand very well what swingweight is, however I was customizing my own racquet using the TW customization tool and it gave me some results I can't understand.

I have two of the same racquet so I assumed that...

if the static weight of both is the same and...

the balance point of both is the same, then...

swingweight of both should be the same.

Is this correct?

But the customization tool said that if I place the weight near the head the swingweight would increase while if I place the weight near the throat it would stay the same. Though like I said above, the final static weight and balance point of both racquets is the same. Doesn't make sense to me...
 
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snoflewis

Hall of Fame
no. it primarily depends on how the weight is distributed within the two rackets. the production process is a very manual one, so one could have more weight towards the ends of the racket (higher sw) while one could have more weight toward the balance point (lower sw).
 

esgee48

Legend
I understand very well what swingweight is, however I was customizing my own racquet using the TW customization tool and it gave me some results I can't understand.

I have two of the same racquet so I assumed that...NOT TRUE unless it is Yonex

if the static weight of both is the same and...

the balance point of both is the same, then...

swingweight of both should be the same.

Is this correct? NO, because SW is based on cm² where balance is based on cm

But the customization tool said that if I place the weight near the head the swingweight would increase while if I place the weight near the throat it would stay the same. Though like I said above, the final static weight and balance point of both racquets is the same. Doesn't make sense to me...
You can have 2 racquets with the same balance and mass, but completely different SW. Reason is the distriubtion of the mass. Racquet 1 could be non polarized with most of the mass centered around the balance point. Now move the mass out to the ends and you would have a polarized racquet 2 set up. Same mass and balance, but because mass has been moved to the tip, your SW shoots way up.
 

Irvin

Talk Tennis Guru
I understand very well what swingweight is, however I was customizing my own racquet using the TW customization tool and it gave me some results I can't understand.

I have two of the same racquet so I assumed that...

if the static weight of both is the same and...

the balance point of both is the same, then...

swingweight of both should be the same.

Is this correct?

But the customization tool said that if I place the weight near the head the swingweight would increase while if I place the weight near the throat it would stay the same. Though like I said above, the final static weight and balance point of both racquets is the same. Doesn't make sense to me...
Just because weight and balance are the same the SW does not have to be the same. SW is inertia calculated at a point 10 cm from the butt. The farther you place weight from that point (the head) the greater the change in SW, the closer you are to the point (the handle) the less the change in SW. The TW tool rounds off the calculations and dependent on how much weight you add there can be little or no change.

if your adding weight anywhere inertia WILL go up. You should know how to calculate those changes if you want closer specs.
 

Irvin

Talk Tennis Guru
I have two of the same racquet so I assumed that...

if the static weight of both is the same and...

the balance point of both is the same, then...

swingweight of both should be the same.

is this correct?
The inertia of a tennis racket is measured at the center of mass. But that is not the SW. if you want to calculate the SW you must use the parallel axis theore. To use the parallel axis theorem you multiply the square of the distance between the new axis and the center of mass times the mass and add that product to the inertia. You may have seen the formula SW = RW + mr^2 which says the same thing. Inertia is mr*2 so the closer the mass is to the center of mass the less change it makes to inertia. Adding mass at the center of mass makes no change at all to the physical object’s inertia. it is safe to assume if 2 or more of the same racket were made in the same mould with the same layup then the inertia of all the rackets would be very closer (but not exact.) Therefore it you match 2 or more of the same rackets weight and balance your SW will also be close.
 

Slowtwitcher

Hall of Fame
Give me 1 example. All I am asking for is 1.
What do you mean one example, you want me to tell you about "these two racquets I have"?

It's possible for two racquets of same model to have same weight and balance and different swingweight. This happens all the time, more often with some manufacturers.
 

Irvin

Talk Tennis Guru
What do you mean one example, you want me to tell you about "these two racquets I have"?

It's possible for two racquets of same model to have same weight and balance and different swingweight. This happens all the time, more often with some manufacturers.
I agree it is not only possible but highly probable. My contention is that is you properly match the weight an balance you SW will be close enough 99% of tennis players could not tell the difference. Also let me give you an example say you have an 18x20 93P and the specs are what TW publishes. SW 329, weight 346 g, and 31.5 cm balance. That being the case your RW is (SW = RW + mrr) 329 - .346*21.5*21.5 = ~169. If you go out and find another 18x20 93P with the same weight and balance chances are the RW will be within a few points of 169. But they could be different but not enough for most players to notice. If the balance and weight are the same. The difference in RW will be exactly the same as the difference in SW.
 

Slowtwitcher

Hall of Fame
I agree it is not only possible but highly probable. My contention is that is you properly match the weight an balance you SW will be close enough 99% of tennis players could not tell the difference. Also let me give you an example say you have an 18x20 93P and the specs are what TW publishes. SW 329, weight 346 g, and 31.5 cm balance. That being the case your RW is (SW = RW + mrr) 329 - .346*21.5*21.5 = ~169. If you go out and find another 18x20 93P with the same weight and balance chances are the RW will be within a few points of 169. But they could be different but not enough for most players to notice. If the balance and weight are the same. The difference in RW will be exactly the same as the difference in SW.
Did you have somebody else write this post? Do you have split personality?
 

LuisM

New User
You can have 2 racquets with the same balance and mass, but completely different SW. Reason is the distriubtion of the mass. Racquet 1 could be non polarized with most of the mass centered around the balance point. Now move the mass out to the ends and you would have a polarized racquet 2 set up. Same mass and balance, but because mass has been moved to the tip, your SW shoots way up.
I hear what you say. So if you are trying to match two of the same racquet just matching weight and balance could still result in different SW's?
 

LuisM

New User
I agree it is not only possible but highly probable. My contention is that is you properly match the weight an balance you SW will be close enough 99% of tennis players could not tell the difference. Also let me give you an example say you have an 18x20 93P and the specs are what TW publishes. SW 329, weight 346 g, and 31.5 cm balance. That being the case your RW is (SW = RW + mrr) 329 - .346*21.5*21.5 = ~169. If you go out and find another 18x20 93P with the same weight and balance chances are the RW will be within a few points of 169. But they could be different but not enough for most players to notice. If the balance and weight are the same. The difference in RW will be exactly the same as the difference in SW.
Thanks for the explanation. Don't know if I missed it, what's RW?
 

Irvin

Talk Tennis Guru
Thanks for the explanation. Don't know if I missed it, what's RW?
RW is recoil weight or The inertia of a physical object at the center of mass. It defines how mass is distributed around the center of mass.
 

Irvin

Talk Tennis Guru
I hear what you say. So if you are trying to match two of the same racquet just matching weight and balance could still result in different SW's?
Maybe but you could also easily match everything. More often than not you can match weight and balance by adding the difference of weight between 2 rackets at 1 point. If you split that weight into 2 equal amount and distribute that weight equidistant above and below that 1 point the inertia, SW, or RW (whatever you want to call it) always goes up. Therefore by dividing the weight usually you can match weight, balance, RW, and SW.
 

HitMoreBHs

Semi-Pro
All I can say is that I learned 90% of what I know about racquet swingweight from @Irvin ’s posts. Since I’m a medic and not an engineer, some of it still boggles my mind, but every day is a learning day!
 
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