Plowthru vs SW

[paulfreda]

Question for those who play with a highly polarized frame;
i.e. high Swingweight [ > 350].

Do you feel you get good plowthru with it ?
Does it feel sluggish getting the head to move initially ?

Do you get the same plowthru you would get with a frame of similar
weight but non polarized / low swingweight ?

 

[Meaghan]

My rackets are not polarised (end to end) in fact i would say its depolarised.

But....I do add a few gramms @ 12" to push the SW up to around he 360 mark.

It helps in a number of ways. It doesnt feel sluggish, yes its heavy but I dont have to swing much on volleys for instance and on groundstrokes the added SW brings the racket round nicely. More about technique than overswinging (which i am liable to do).

Its different for everyone and there is a weight and SW issue for me when it gets above a certain mark and ive found i do like my racket weight and SW fairly similar around the 360 mark.

Also it does create a super stable frame. And no I dont personally get the same plow/feel from lower weight and SW rackets

 

[Shangri La]

Polarization and swingweight are two different things; they're not directly related to each other.

But yea, higher sw usually gives you better plowthrough.

 

[jrod]

Interesting question. For starters, the heaviest frame I've ever used is the k90 which has a posted SW of 336 or so. So I'm not qualified to comment directly on SW's heavier than this. However, I do believe that the manner in which weight is distributed in a frame impact's it's perceived plow through. My sense is the more polarized a frame is, the greater the perceived plow through. I currently use the PB10mid which is a rather polarized frame and I find it's plow through almost on par with the k90 even though it is a lighter frame.

I'd be curious to here from TW's professor on this subject...

 

[PED]

OP, I just moved from a 348g frame with a 328SW to a 337g frame with a 345g SW.

The heavier frame is a bit more solid, especially on return of serve but the tradeoff in dropping 11g in static weight has been offset with better bat speed. I get excellent plow from the higher SW and I've not had any stability issues in groundstrokes either.

I will add that I would NOT like to drop any lower in weight from that 337g static weight. I think there does have to be some baseline degree of mass for stability purposes.

One last point, I briefly used a Bab PSL-gt for a few weeks before moving to my current stick. The Bab was almost a polar opposite from my current stick. The Bab's SW is quite low (314 in stock form) and I had to add lead at the tip to bring it up. With the lead added, the static weight went to 345g but the overall lack of mass in the hoop meant that I never got the plow I was looking for. Great thread

 

[larry10s]

OP, I just moved from a 348g frame with a 328SW to a 337g frame with a 345g SW.

The heavier frame is a bit more solid, especially on return of serve but the tradeoff in dropping 11g in static weight has been offset with better bat speed. I get excellent plow from the higher SW and I've not had any stability issues in groundstrokes either.

I will add that I would NOT like to drop any lower in weight from that 337g static weight. I think there does have to be some baseline degree of mass for stability purposes.

One last point, I briefly used a Bab PSL-gt for a few weeks before moving to my current stick. The Bab was almost a polar opposite from my current stick. The Bab's SW is quite low (314 in stock form) and I had to add lead at the tip to bring it up. With the lead added, the static weight went to 345g but the overall lack of mass in the hoop meant that I never got the plow I was looking for. Great thread

what are the balance points of your racquets??

 

[larry10s]

Question for those who play with a highly polarized frame;
i.e. high Swingweight [ > 350].

Do you feel you get good plowthru with it ?
Does it feel sluggish getting the head to move initially ?

Do you get the same plowthru you would get with a frame of similar
weight but non polarized / low swingweight ?

the balance point is another part of the equasion. i have vantage racquets that strung are 345gm and 8 points hl(318mm) the sw is 333 measured by vantage. i switched to a heavier racquet 354gm strung 10 points hl (311mm) sw 334. plowthru feel similar. moreheadlight alittle "whippier".
i dont beleive that non polarized = low swingweight. depends on the balance point

 

[jrod]

...i dont beleive that non polarized = low swingweight. depends on the balance point

Lets take 2 frames with identical static weights and balance points. The same balance point can be established in both a polarized manner and unpolarized manner so lets assume the 1st frame has a polarized distribution of weight and the 2nd frame does not.

Which frame has a higher SW?

Which frame has greater perceived plow through?

 

[Sublime]

Which frame has a higher SW?

Hands down the polarized one, because it will have more weight distributed towards the tip (12 o'clock).

Which frame has greater perceived plow through?

Hands down, the polarized one again. Because the parameters that affect plow through are recoil weight, balance point, and static weight. With balance point and static weight being held constant that just leaves recoil weight.

The whole point of polarizing a racket is to increase it's recoil weight with minimal static weight increase. So more recoil weight = more plow through in this case.

 

[PED]

the balance point is another part of the equasion. i have vantage racquets that strung are 345gm and 8 points hl(318mm) the sw is 333 measured by vantage. i switched to a heavier racquet 354gm strung 10 points hl (311mm) sw 334. plowthru feel similar. moreheadlight alittle "whippier".
i dont beleive that non polarized = low swingweight. depends on the balance point

I agree with what you are saying, balance is a key. Balance point on my Radical Pro is 33.75cm

 

[jrod]

^^ Sublime - Thanks for your answers. You've essentially agreed my original conjecture that the more polarized the frame, the greater the plow through. So if a racquet manufacturer wants to maximize plow through for a given SW, they should distribute the weight in a polarized manner. I think this is exactly what Volkl did with the PB10mid.

 

[travlerajm]

Question for those who play with a highly polarized frame;
i.e. high Swingweight [ > 350].

Do you feel you get good plowthru with it ?
Does it feel sluggish getting the head to move initially ?

Do you get the same plowthru you would get with a frame of similar
weight but non polarized / low swingweight ?

Plowthru is mostly a function of SW.

If you use a high SW, it's important to have the balance right or else the head won't come around fast enough. I believe this is more important than worrying about how polarized your frame is.

For a given SW and static weight, the more HL your frame is, the slower the head will come around. This may sound counterintuitive, but it's true.

Also, adding mass to the tip will slow down the head, while adding mass to the handle will speed up the head (much moreso when adding to the top of the handle than when adding to the butt).

While I don't worry so much about polarization anymore as I do about balance, I do believe that adding weight to the upper half of the hoop is the way to go, mainly because it gives a more uniform ball response over the entire stringbed.

My preferred SW is in the mid to high 360s.

 

[paulfreda]

What does it mean to have "the balance right "

Is there an ideal balance point that varies with SW or Static Wt ?

How do you calculate what this needs to be ?

 

[travlerajm]

What does it mean to have "the balance right "

Is there an ideal balance point that varies with SW or Static Wt ?

How do you calculate what this needs to be ?

For me, the racquethead comes around at the perfect speed when mgr/I = 21.0.

m = mass of racquet in kg
g = 980 cm/s^2
r = balance from butt end in cm
I = SW around axis through handle end (not the 10-cm axis)

As long as mgr/I = 21, the racquet feels balanced to me, whether the SW = 300 or 370. If it's only 20.5, the head doesn't come around fast enough and I spray my forehand.

 

[cellofaan]

^^ Sublime - Thanks for your answers. You've essentially agreed my original conjecture that the more polarized the frame, the greater the plow through. So if a racquet manufacturer wants to maximize plow through for a given SW, they should distribute the weight in a polarized manner. I think this is exactly what Volkl did with the PB10mid.

Not exactly. He/she says that for a given weight and balance, the more polarised frame will have the better plowthrough, because the recoilweight (and SW) will be higher.
For a given SW, the static weight and balance are the variables which decide the plowthrough. For a given SW and balance, a higher static weight gives a better plowtrough. That means that for a given SW, a depolarised racquet will have a better plowthrough.
I don't remember whether a higher or lower balance was better.

 

[Superman1272]

For a given SW and static weight, the more HL your frame is, the slower the head will come around.

Also, adding mass to the tip will slow down the head,

Apologies... This seems contradictary. Please explain.

 

[travlerajm]

Apologies... This seems contradictary. Please explain.

It's not contradictory if you read it carefully.

Adding mass to the tip increases SW. My statement about balance is for a given SW and static weight.

 

[Dreamcastin]

it is contradictary travlerajm, you say the more headlight a frame is the slower the head will come around,(which i agree with) but then you say more weight in the handle(making it more headlight)will make the head come around faster??????????????

 

[travlerajm]

it is contradictary travlerajm, you say the more headlight a frame is the slower the head will come around,(which i agree with) but then you say more weight in the handle(making it more headlight)will make the head come around faster??????????????

No what I wrote is not contradictory. Read it carefully.

Adding weight to the handle will change the static weight. I said that the more HL a frame is (for a given SW and static weight), the slower it will come around.

 

[jrod]

....For a given SW and static weight, the more HL your frame is, the slower the head will come around. This may sound counterintuitive, but it's true.

travlerajm - It does strike me as counterintuitive. See below:

Also, adding mass to the tip will slow down the head, while adding mass to the handle will speed up the head (much moreso when adding to the top of the handle than when adding to the butt).

Adding weight to the head will increase the frames SW, and as a consequence slows the head speed down. I can agree with this.

Now, adding weight to the butt doesn't alter SW that much but it does increase the static weight. So the frame becomes more headlight and you claim it increases the head speed relative to what it was before you weighted the butt. OK, now suppose we have another frame that has an identical SW as this modified one but it is more headlight. This would seem to imply more of it's weight is located towards the butt, correct? Yet, according to your 1st statement it's head should come around slower.

Can you please explain?

 

[travlerajm]

travlerajm - It does strike me as counterintuitive. See below:

Adding weight to the head will increase the frames SW, and as a consequence slows the head speed down. I can agree with this.

Now, adding weight to the butt doesn't alter SW that much but it does increase the static weight. So the frame becomes more headlight and you claim it increases the head speed relative to what it was before you weighted the butt. OK, now suppose we have another frame that has an identical SW as this modified one but it is more headlight. This would seem to imply more of it's weight is located towards the butt, correct? Yet, according to your 1st statement it's head should come around slower.

Can you please explain?

If two racquets have the same swingweight and static weight, but one is more headlight, then yes, the more HL one probably has more weight located near the butt. However, it also probably has less weight located near the top of the handle. So it will come around slower. As I said before, weight added near the top of the handle will increase the head speed moreso than weight in the butt.

 

[jrod]

If two racquets have the same swingweight and static weight, but one is more headlight, then yes, the more HL one probably has more weight located near the butt. However, it also probably has less weight located near the top of the handle. So it will come around slower. As I said before, weight added near the top of the handle will increase the head speed moreso than weight in the butt.

I know what you said, but I'm still having trouble with it. As you stated earlier, it's counter-intuitive and my intuition doesn't get it.

Again, assume 2 frames with identical SW's. The frame with more weight in the head implies a weight distribution that is more polarized. It would seem that for a fixed amount of force applied it will take more effort to move a mass further from the grip than it would if that mass was closer the grip to achieve a fixed head speed.

Can you provide an explanation, preferably relying on simple physics to explain why this isn't the case?

The only thing I can think of is that with identical SW's, the more polarized frame has lower total mass than the less polarized frame. As a result, the less polarized frame has a larger total mass and therefore takes more effort.

 

[travlerajm]

I know what you said, but I'm still having trouble with it. As you stated earlier, it's counter-intuitive and my intuition doesn't get it.

Again, assume 2 frames with identical SW's. The frame with more weight in the head implies a weight distribution that is more polarized. It would seem that for a fixed amount of force applied it will take more effort to move a mass further from the grip than it would if that mass was closer the grip to achieve a fixed head speed.

Can you provide an explanation, preferably relying on simple physics to explain why this isn't the case?

This has nothing to do with how much effort it takes to move your racquet. I'm talking about your racquet's natural swing speed.

A groundstroke path is high-to-low-to-high. It has a natural swing speed governed by the laws of physics. That is, it obeys the equations of motion for a physical pendulum.

The frequency of a physical pendulum is proportional to sqrt(MgR/I), where M is the mass, g is the acceleration of gravity, and R is the distance from the axis of rotation to the center of mass, and I is the moment of inertia about the axis of rotation.

In the case of a racquet, M is the racquet mass, R is the distance from butt to balance point, and I = SW +20MR - 100M, where SW = swingweight about 10-cm axis.

Adding mass to the top of the handle increases MgR/I. Adding mass to the butt has almost no change on MgR/I. And adding mass to the racquet head decreases MgR/I.

I prefer MgR/I to be about 21.0 for my racquet to swing at the right speed (M in kg, g in cm/s^2, R in cm, I in kg-cm^2). if the value is less than 20.8, I have trouble getting the head around fast enough, and I spray my groundstrokes.

I can play well with SW as low as 300 or as high as 370 as long as MgR/I is about 21. But I much prefer SW in the high 360s to get the stability I like.

 

[jrod]

travlerajm - Sorry, but still not with you here so bear with me. You stated that for a given SW, greater head speed can be achieved by placing mass further from the handle butt (more polarized). This is the counter-intuitive statement that I'm trying to understand.

The further this mass moves from the handle, the higher the SW will be. So in order to keep a constant SW, one has to reduce the overall mass of the frame, right? So is the lower overall mass associated with the higher polarized frame the reason why it achieves a higher head speed?

Edit -> I re-read you last post and think I may have misinterpreted you. I now see you are making a distinction between positioning mass in 3 distinct places:

1. Racquet butt, between the hand and the wrist.
2. Racquet thoat, just above the hand but below the bridge.
3. Racquet head, presumably somewhere in the hoop.

I've been thinking strictly about cases 1 and 3. Case 2 is the one in which you maintain additional head speed can be achieved, whereas case 3 decreases head speed. Is this correct???

 

[travlerajm]

Edit -> I re-read you last post and think I may have misinterpreted you. I now see you are making a distinction between positioning mass in 3 distinct places:

1. Racquet butt, between the hand and the wrist.
2. Racquet thoat, just above the hand but below the bridge.
3. Racquet head, presumably somewhere in the hoop.

I've been thinking strictly about cases 1 and 3. Case 2 is the one in which you maintain additional head speed can be achieved, whereas case 3 decreases head speed. Is this correct???

Yes. That's correct.

 

[DEH]

This has nothing to do with how much effort it takes to move your racquet. I'm talking about your racquet's natural swing speed.

A groundstroke path is high-to-low-to-high. It has a natural swing speed governed by the laws of physics. That is, it obeys the equations of motion for a physical pendulum.

The frequency of a physical pendulum is proportional to sqrt(MgR/I), where M is the mass, g is the acceleration of gravity, and R is the distance from the axis of rotation to the center of mass, and I is the moment of inertia about the axis of rotation.

In the case of a racquet, M is the racquet mass, R is the distance from butt to balance point, and I = SW +20MR - 100M, where SW = swingweight about 10-cm axis.

Adding mass to the top of the handle increases MgR/I. Adding mass to the butt has almost no change on MgR/I. And adding mass to the racquet head decreases MgR/I.

I prefer MgR/I to be about 21.0 for my racquet to swing at the right speed (M in kg, g in cm/s^2, R in cm, I in kg-cm^2). if the value is less than 20.8, I have trouble getting the head around fast enough, and I spray my groundstrokes.

I can play well with SW as low as 300 or as high as 370 as long as MgR/I is about 21. But I much prefer SW in the high 360s to get the stability I like.

I tried to work this equation and I can not get it. Could you write the equation with your racquet so I can see what I am doing wrong or email me. dehorton73 @ msn dotcom
I think that I am have the problem with the I=sw +20MR-100M
Thanks

 

[cellofaan]

I tried to work this equation and I can not get it. Could you write the equation with your racquet so I can see what I am doing wrong or email me. dehorton73 @ msn dotcom
I think that I am have the problem with the I=sw +20MR-100M
Thanks

For a wilson k90 it would be:

M = 0,354 kg
g = 981 cm/s^2
R = 31,4325
SW = 336

I = 336 + (20*0,354*31,4325) - (100*0,354)
= 523,1421

MgR/I = (0,354*981*31,4325) / 523,1421
= 20,8656

Hope this helps

 

[DEH]

For a wilson k90 it would be:

M = 0,354 kg
g = 981 cm/s^2
R = 31,4325
SW = 336

I = 336 + (20*0,354*31,4325) - (100*0,354)
= 523,1421

MgR/I = (0,354*981*31,4325) / 523,1421
= 20,8656

Hope this helps

I am such an idiot, I see what I was doing wrong now. Thanks

 

[jrod]

This has nothing to do with how much effort it takes to move your racquet. I'm talking about your racquet's natural swing speed.

A groundstroke path is high-to-low-to-high. It has a natural swing speed governed by the laws of physics. That is, it obeys the equations of motion for a physical pendulum.

The frequency of a physical pendulum is proportional to sqrt(MgR/I), where M is the mass, g is the acceleration of gravity, and R is the distance from the axis of rotation to the center of mass, and I is the moment of inertia about the axis of rotation.

In the case of a racquet, M is the racquet mass, R is the distance from butt to balance point, and I = SW +20MR - 100M, where SW = swingweight about 10-cm axis.

Adding mass to the top of the handle increases MgR/I. Adding mass to the butt has almost no change on MgR/I. And adding mass to the racquet head decreases MgR/I.

I prefer MgR/I to be about 21.0 for my racquet to swing at the right speed (M in kg, g in cm/s^2, R in cm, I in kg-cm^2). if the value is less than 20.8, I have trouble getting the head around fast enough, and I spray my groundstrokes.

I can play well with SW as low as 300 or as high as 370 as long as MgR/I is about 21. But I much prefer SW in the high 360s to get the stability I like.

travlerajm - Interesting....I just computed MgR/I for both my PB10mids and I got 20.88 for the one I prefer (SW = 324) and 20.68 for the one I occasionally have trouble with in doubles (SW = 329). So it seems that you and I both have similar thresholds for the natural frequency.

I'm still somewhat surprised I am so sensitive to such a small difference in SW, but I can definitely feel it. The head pro at my club asked me if I marked the frames so I know which is which and I told him no because all I need to do is swing them and can immediately tell the difference. He tried and could not discern any difference whatsoever. Odd...

 

[olliess]

A groundstroke path is high-to-low-to-high. It has a natural swing speed governed by the laws of physics. That is, it obeys the equations of motion for a physical pendulum.

The frequency of a physical pendulum is proportional to sqrt(MgR/I), where M is the mass, g is the acceleration of gravity, and R is the distance from the axis of rotation to the center of mass, and I is the moment of inertia about the axis of rotation.

I'm confused... Don't some of the terms in MR/I cancel?

 

[TheLama]

travlerajm - Interesting....I just computed MgR/I for both my PB10mids and I got 20.88 for the one I prefer (SW = 324) and 20.68 for the one I occasionally have trouble with in doubles (SW = 329). So it seems that you and I both have similar thresholds for the natural frequency.

I'm still somewhat surprised I am so sensitive to such a small difference in SW, but I can definitely feel it. The head pro at my club asked me if I marked the frames so I know which is which and I told him no because all I need to do is swing them and can immediately tell the difference. He tried and could not discern any difference whatsoever. Odd...

Except for matching frames, this info is interesting but esoteric. You need to play with the stick that promotes the best ball quality on your opponents side of the net by using the heaviest stick you can wield.

It's as simple as that.

 

[Jon Carter]

For me, the racquethead comes around at the perfect speed when mgr/I = 21.0.

m = mass of racquet in kg
g = 980 cm/s^2
r = balance from butt end in cm
I = SW around axis through handle end (not the 10-cm axis)

As long as mgr/I = 21, the racquet feels balanced to me, whether the SW = 300 or 370. If it's only 20.5, the head doesn't come around fast enough and I spray my forehand.

Hmm. What does this mean? How do you calculate this travlerajm? Mind sharing with us?

 

[travlerajm]

Hmm. What does this mean? How do you calculate this travlerajm? Mind sharing with us?

The wrist axis is approximately lined up with the end of the handle.

You can use the Parallel Axis Theorem to calculate the swingweight about any axis along the length of the racquet.

The easiest way to do this is to convert first to recoil weight (Ic), the axis through the balance point.

Ic = SW - M(R - 10)^2

I = Ic + MR^2

 

[Jon Carter]

Travlerajm,

So ok, I got the specs down using the equation (M, R and SW). Using TW specs calculator, one option (two parts) is to add at 11 and at the top of handle. Another option (three part adding) is to add at 10 and 9 and a counterweight in the butt.

What is your view on this. Is 'superpolarized' the best (in your opinion) as compared to adding it at the top of the handle to achieve the exact same specs.

Input is appreciated.

 

[travlerajm]

Travlerajm,

So ok, I got the specs down using the equation (M, R and SW). Using TW specs calculator, one option (two parts) is to add at 11 and at the top of handle. Another option (three part adding) is to add at 10 and 9 and a counterweight in the butt.

What is your view on this. Is 'superpolarized' the best (in your opinion) as compared to adding it at the top of the handle to achieve the exact same specs.

Input is appreciated.

I prefer to concentrate a lot of weight in the 10 and 2 region. I usually spread it out between 9 and 11 and between 1 and 3. If the frame is flexible, some mass at 12 also might be needed.

I think having a well-balanced frame that swings at the correct speed is more important than worrying about whether your frame is 'superpolarized.' However, I've found that minimizing the amount of mass located in the throat and lower hoop will improve overall performance.

Once I add enough weight to the hoop to get my swingweight close to my target, I use the swingweight calculator to get an accurate swingweight reading.

Then I use a speadsheet to calculate where on the handle I will need to counterweight in order to get to my target balance.

 

[Jon Carter]

I prefer to concentrate a lot of weight in the 10 and 2 region. I usually spread it out between 9 and 11 and between 1 and 3. If the frame is flexible, some mass at 12 also might be needed.

I think having a well-balanced frame that swings at the correct speed is more important than worrying about whether your frame is 'superpolarized.' However, I've found that minimizing the amount of mass located in the throat and lower hoop will improve overall performance.

Once I add enough weight to the hoop to get my swingweight close to my target, I use the swingweight calculator to get an accurate swingweight reading.

Then I use a speadsheet to calculate where on the handle I will need to counterweight in order to get to my target balance.

Hmm. Alright. I will try adding weights at 10 and 2 first then. However, adding weights at the top of the handle and adding them to the ends have different effects on the "swinging speed" (based on the other posts you made) even if they achieve the same balance.

So now the amount of lead added to the top of the hoop does not matter, but rather the balance of the racquet matters much more? Even though the lead can be placed on the racquet in many ways to achieve the same balance, in your point of view, polarization is preferred compared to adding weight at the top of the handle (unless there is no choice, that is)

Is that correct?

 

[normrose]

Hi Travlerjam – is it possible for you to explain in words instead of explaining by formula why the head comes around faster if the weight is placed towards the top of the handle as opposed to placing the lead in the butt.

Also is this method of lead placement more in line with what John Cauthen advocated many posts ago?

 

[DEH]

For me, the racquethead comes around at the perfect speed when mgr/I = 21.0.

m = mass of racquet in kg
g = 980 cm/s^2
r = balance from butt end in cm
I = SW around axis through handle end (not the 10-cm axis)

As long as mgr/I = 21, the racquet feels balanced to me, whether the SW = 300 or 370. If it's only 20.5, the head doesn't come around fast enough and I spray my forehand.

Does this work for any lenght of racquets?

 

[travlerajm]

Does this work for any lenght of racquets?

Yes. .

 

[larry10s]

Hi Travlerjam – is it possible for you to explain in words instead of explaining by formula why the head comes around faster if the weight is placed towards the top of the handle as opposed to placing the lead in the butt.

Also is this method of lead placement more in line with what John Cauthen advocated many posts ago?

i second that request.

 

[DEH]

Yes. .

\


So I have a known racquet that I like that is 27" long and using your formula it is very close to what you like. So if I go with a shorter racquet I can just plug the numbers in and find the right balance point and weight for that new one?

 

[travlerajm]

Hi Travlerjam – is it possible for you to explain in words instead of explaining by formula why the head comes around faster if the weight is placed towards the top of the handle as opposed to placing the lead in the butt.

Also is this method of lead placement more in line with what John Cauthen advocated many posts ago?

Some understanding of physics is required to understand this.
You must understand moments.

The first moment is the product of the mass x the lever arm. If the first moment increases, then a force acting on the racquet (in this case gravity) has more leverage to apply to your racquet, so the racquet accelerates downward faster from the top of your swing.

The second moment is the swingweight. It is called the moment of inertia. This is a measure of how hard it is for an applied force (in this case gravity) to accelerate your frame.

The goal is to make it easier for gravity to accelerate your racquet from the top of the backswing downward to the bottom of your swing.

If the ratio of the first moment to the second moment increases, then the head speed will increase.

When adding mass, the further away from the butt end, more the first moment (mass x lever arm) will increase, with the first moment increasing linearly with the distance from the butt at which the mass is placed.

For that same added mass, the second moment (moment of inertia, aka swingweight) increases with the square of the distance from the butt end.

Since the goal is to increase the first moment while minimizing increase in second moment, there is an optimum point along the length of the racquet for addition of a given mass.

That is, adding mass too close to the butt will have negligible increase in first moment, while adding mass too close to the tip will increase the second moment too much.

The optimum point usually is near the top of the handle.

 

[ronalditop]

Some understanding of physics is required to understand this.
You must understand moments.

The first moment is the product of the mass x the lever arm. If the first moment increases, then a force acting on the racquet (in this case gravity) has more leverage to apply to your racquet, so the racquet accelerates downward faster from the top of your swing.

The second moment is the swingweight. It is called the moment of inertia. This is a measure of how hard it is for an applied force (in this case gravity) to accelerate your frame.

The goal is to make it easier for gravity to accelerate your racquet from the top of the backswing downward to the bottom of your swing.

If the ratio of the first moment to the second moment increases, then the head speed will increase.

When adding mass, the further away from the butt end, more the first moment (lever arm) will increase, with the first moment increasing linearly with the distance from the butt at which the mass is placed.

For that same added mass, the second moment (moment of inertia, aka swingweight) increases with the square of the distance from the butt end.

Since the goal is to increase the first moment while minimizing increase in second moment, there is an optimum point along the length of the racquet for addition of a given mass.

That is, adding mass too close to the butt will have negligible increase in first moment, while adding mass too close to the tip will increase the second moment too much.

The optimum point usually is near the top of the handle.

That is very true. I have experienced a lot with lead at the handle and I found that the best place to put it is on top of the handle, at about 8-8.5 inches top. I have also found that racquets with a longer handle perform way better than racquets with short handles.

 

[travlerajm]

\


So I have a known racquet that I like that is 27" long and using your formula it is very close to what you like. So if I go with a shorter racquet I can just plug the numbers in and find the right balance point and weight for that new one?

Yes. As long as you carefully measure the weight, balance, and swingweight.

 

[paulfreda]

Some understanding of physics is required to understand this.
You must understand moments.

The first moment is the product of the mass x the lever arm. If the first moment increases, then a force acting on the racquet (in this case gravity) has more leverage to apply to your racquet, so the racquet accelerates downward faster from the top of your swing.

The second moment is the swingweight. It is called the moment of inertia. This is a measure of how hard it is for an applied force (in this case gravity) to accelerate your frame.

The goal is to make it easier for gravity to accelerate your racquet from the top of the backswing downward to the bottom of your swing.

If the ratio of the first moment to the second moment increases, then the head speed will increase.

When adding mass, the further away from the butt end, more the first moment (mass x lever arm) will increase, with the first moment increasing linearly with the distance from the butt at which the mass is placed.

For that same added mass, the second moment (moment of inertia, aka swingweight) increases with the square of the distance from the butt end.

Since the goal is to increase the first moment while minimizing increase in second moment, there is an optimum point along the length of the racquet for addition of a given mass.

That is, adding mass too close to the butt will have negligible increase in first moment, while adding mass too close to the tip will increase the second moment too much.

The optimum point usually is near the top of the handle.

Great explanation thank you !
Clear, simple and concise.

Continuing ..............
So if I hang my frame from the butt with 2 nails and let it swing, the higher the frequency of oscillation corresponds to high SW ?

Do I need to calibrate or normalize this against the base SW of the frame in the stock condition ?

 

[paulfreda]

That is very true. I have experienced a lot with lead at the handle and I found that the best place to put it is on top of the handle, at about 8-8.5 inches top. I have also found that racquets with a longer handle perform way better than racquets with short handles.

It almost sounds like Trav and John Cauthen are in agreement here as JC advocates lead in the same general place. But I think for different reasons.

 

[jrod]

..........
So if I hang my frame from the butt with 2 nails and let it swing, the higher the frequency of oscillation corresponds to high SW ?

....

My interpretation is that a higher frequency of oscillation corresponds to a lower SW. This is consistent with the formula trav provided where an increase in SW decreases the ratio of mgr/I.

 

[travlerajm]

Great explanation thank you !
Clear, simple and concise.

Continuing ..............
So if I hang my frame from the butt with 2 nails and let it swing, the higher the frequency of oscillation corresponds to high SW ?

No. Higher frequency of oscillation corresponds to higher ratio of first moment to SW. Thus, higher frequency of oscillation generally corresponds to lower SW.

Do I need to calibrate or normalize this against the base SW of the frame in the stock condition ?

For measuring SW, I highly recommend using the TW swingweight measurement tool. I usually use 2 pencils to hang the frame from the top string, then use an online stopwatch. Along with a good kitchen or postage scale and a yardstick, you'll have everything you need to take the measurements.

Having an accurate SW measurement is essential for effective customization. The published specs are usually not accurate enough (due to large tolerances) to properly tune a racquet for high performance.

 

[normrose]

travlerajm;4222354]Some understanding of physics is required to understand this.
You must understand moments.

The first moment is the product of the mass x the lever arm. If the first moment increases, then a force acting on the racquet (in this case gravity) has more leverage to apply to your racquet, so the racquet accelerates downward faster from the top of your swing.

The second moment is the swingweight. It is called the moment of inertia. This is a measure of how hard it is for an applied force (in this case gravity) to accelerate your frame.

The goal is to make it easier for gravity to accelerate your racquet from the top of the backswing downward to the bottom of your swing.

If the ratio of the first moment to the second moment increases, then the head speed will increase.

When adding mass, the further away from the butt end, more the first moment (mass x lever arm) will increase, with the first moment increasing linearly with the distance from the butt at which the mass is placed.

For that same added mass, the second moment (moment of inertia, aka swingweight) increases with the square of the distance from the butt end.

Since the goal is to increase the first moment while minimizing increase in second moment, there is an optimum point along the length of the racquet for addition of a given mass.

That is, adding mass too close to the butt will have negligible increase in first moment, while adding mass too close to the tip will increase the second moment too much.

The optimum point usually is near the top of the handle

 

[normrose]

travlerajm;4222354]Some understanding of physics is required to understand this.
You must understand moments.

The first moment is the product of the mass x the lever arm. If the first moment increases, then a force acting on the racquet (in this case gravity) has more leverage to apply to your racquet, so the racquet accelerates downward faster from the top of your swing.

The second moment is the swingweight. It is called the moment of inertia. This is a measure of how hard it is for an applied force (in this case gravity) to accelerate your frame.

The goal is to make it easier for gravity to accelerate your racquet from the top of the backswing downward to the bottom of your swing.

If the ratio of the first moment to the second moment increases, then the head speed will increase.

When adding mass, the further away from the butt end, more the first moment (mass x lever arm) will increase, with the first moment increasing linearly with the distance from the butt at which the mass is placed.

For that same added mass, the second moment (moment of inertia, aka swingweight) increases with the square of the distance from the butt end.

Since the goal is to increase the first moment while minimizing increase in second moment, there is an optimum point along the length of the racquet for addition of a given mass.

That is, adding mass too close to the butt will have negligible increase in first moment, while adding mass too close to the tip will increase the second moment too much.

The optimum point usually is near the top of the handle

Traverlejam - Thanks for the detailed reply.