Optimum Racquet Balance for Performance II - MgR/I Data for ATP Pros

[corners]

Originally Posted by ART ART

Again,

can you comment this specs travlerajm ?

Thnaks

Hey Art,

I do believe that Trav thinks that tuning MgR/I is more important than the 380 rule. The easiest way for you to get to 21 is to either remove some lead at12 or repoition it to 3&9. Alternatively you could add 15 grams at the top of the grip but that is a pretty big addition. On the other hand, some people find that high static weight isn't so bothersome when MgR/I is in their preferred range. Adding at the top of the grip would also keep you in the 380 "club"

[klementine79]

Originally Posted by corners

Maybe 21.0 based on your height. Spec out your frame and go from there. Once at 21.0 you can play around with 5 grams or so at the top of the grip to raise it to 21.1 or a gram or two at twelve to lower below 21. For someone like you, with experience with lead, the fun part is tuning it until it feels just right.

^Thanks. That's what I thought. Don't understand how/why height has any relevance. Seems like arm length is more relevant.

I guess the logic is taller=longer arms. This is not always the case though.

[travlerajm]

Originally Posted by klementine79

^Thanks. That's what I thought. Don't understand how/why height has any relevance. Seems like arm length is more relevant.

I guess the logic is taller=longer arms. This is not always the case though.

Yes. The taller=longer arms was my logic.

I also noticed that the racquets I tuned for myself seemed to work great when friends who were my size tried them, while really short guys couldn't control the ball at all.

Then when I compared average MgR/I values of WTA players to ATP players, it lent support to the shorter = higher MgR/I story.

[klementine79]

^travlerajm?

I've always wanted to ask you your opinion of John Cauthen.

Were your theories (before being defined by physics and empirical data) at all influenced by him?

[TheLambsheadrep]

travlerajm, is achieving MR^2 to be = 385, or MgR/I to be = 20.7-21.1 more desirable?

And I'm working on comparative data based of Jura's 2005 pro data. As of now, Excel says the average STRUNG weight (I added 22 grams to every racquet mass given, since the mass difference of my racquets of strung-unstrung is always around 22g) is 360.7g. This is interesting, because you can see from my summer posts, I just made all my rackets 360g. The thing is, to achieve a MR^2 of 385 with a racquet of 360g, the balance needs to be 5.003pts head light. I thought pro rackets would have been a little more head light than that...

[travlerajm]

Originally Posted by klementine79

^travlerajm?

I've always wanted to ask you your opinion of John Cauthen.

Were your theories (before being defined by physics and empirical data) at all influenced by him?

I read his posts with curiosity. And he was one of a couple of posters (along with MackSamuelHustovisics) that inspired me to start experimenting myself.

I must admit that it took me several years of experimenting before I finally felt like I figured out how the physics of how adding lead works.

At first, I was fascinated that adding as little as a gram or 2 could make such a huge difference to my racquet, even when I added it to the handle.

Adding a gram to the butt seemed to reduce power (I couldn't fully understand why at the time), while adding a gram to the the top of the handle seemed to increase it in some cases.

More than John Cauthen, reading all of the papers by Cross, Brody, Lindsey, Goodwill, etc. really helped me get a base for the impact dynamics. And the MgR/I stuff (i.e., swing dynamics) I figured out myself after lots of fiddling both with my racquets and with excel spreadsheets with logs of my various racquet specs.

Once you can isolate the effects of swing dynamics from the effects of impact dynamics, tuning a racquet gets a lot easier.

[klementine79]

^Impact dynamics seems even more intriguing to me but we have very little control over that. Except for string tension and gauge. Plasticity (flex) and different materials are beyond our control.

Although, pt630 once told me the flex of a racquet can be tampered with. But, I'm not willing to drill holes in the shaft of my racquet, so swing dynamics it is!

[travlerajm]

Originally Posted by klementine79

^Impact dynamics seems even more intriguing to me but we have very little control over that. Except for string tension and gauge. Plasticity (flex) and different materials are beyond our control.

Although, pt630 once told me the flex of a racquet can be tampered with. But, I'm not willing to drill holes in the shaft of my racquet, so swing dynamics it is!

Impact dynamics can be tuned with lead also. That is, the flex and dwell time of your frame can be tuned independently of the strings. And independently of the weighting specs.

For a very stiff frame it is less important, but it still matters.

There are two primary bending nodes - one midway up the handle, and another about 2/3 of the way up the hoop.

Any time you add lead between the nodes, it will stiffen the frame. Adding lead to the throat just beneath the bridge will have maximum stiffening effect. It won't test any differently on an RDC, but it will play stiffer.

Adding lead to the butt (below the bending node) will tend to make the frame play more flexible. Adding lead at 12 will make a big difference on how dead the upper hoop feels.

For a given mass, balance, and swingweight, their are infinite weighting combinations - some stiffer than others.

For example: Let's say you want to add 15g at 3&9 plus 5 grams in the butt to achieve a certain mass, balance, and swingweight. You could alternatively reach the same specs by adding roughly 8g at 12 plus 12g at the top of the handle.

The latter weighting will play much stiffer than the former, even though less weight is added to the hoop. Why? It's because of the mass added at the top of the handle, between the nodes.

If I want a racquet to play stiffer (at the same weighting specs), I move the hoop weight further north (which means less hoop wieght, but more counterweight between the nodes). If I want it to play more flexible, with more dwell time for more spin, I move the weight south more toward 3&9. It's what happens with the counterweighting that affects the stiffness.

[travlerajm]

Originally Posted by TheLambsheadrep

travlerajm, is achieving MR^2 to be = 385, or MgR/I to be = 20.7-21.1 more desirable?

And I'm working on comparative data based of Jura's 2005 pro data. As of now, Excel says the average STRUNG weight (I added 22 grams to every racquet mass given, since the mass difference of my racquets of strung-unstrung is always around 22g) is 360.7g. This is interesting, because you can see from my summer posts, I just made all my rackets 360g. The thing is, to achieve a MR^2 of 385 with a racquet of 360g, the balance needs to be 5.003pts head light. I thought pro rackets would have been a little more head light than that...

I think the keys are:
1. MgR/I needs to be tuned to your personal swing.
2. Swingweight needs to be high enough for stability (at least 350).
3. Swingweight needs to be low enough to be able to serve big for an entire match (less than 380).

I think the 385 MR^2 optimum is simply a convergence of the 3 factors above.

[TheLambsheadrep]

Originally Posted by travlerajm

I think the keys are:
1. MgR/I needs to be tuned to your personal swing.
2. Swingweight needs to be high enough for stability (at least 350).
3. Swingweight needs to be low enough to be able to serve big for an entire match (less than 380).

I think the 385 MR^2 optimum is simply a convergence of the 3 factors above.

So a "performance #" of 385 is the better racquet quality to achieve...?

I do need to calculate swingweight, it's about the only thing I haven't done to my racquets. and my optimal MgR/I would be 21.0 since im right about 6 feet tall, but do you mean something else when you say "needs to be tuned to your personal swing?"

[klementine79]

Originally Posted by travlerajm

Impact dynamics can be tuned with lead also. That is, the flex and dwell time of your frame can be tuned independently of the strings. And independently of the weighting specs.

For a very stiff frame it is less important, but it still matters.

There are two primary bending nodes - one midway up the handle, and another about 2/3 of the way up the hoop.

Any time you add lead between the nodes, it will stiffen the frame. Adding lead to the throat just beneath the bridge will have maximum stiffening effect. It won't test any differently on an RDC, but it will play stiffer.

Adding lead to the butt (below the bending node) will tend to make the frame play more flexible. Adding lead at 12 will make a big difference on how dead the upper hoop feels.

For a given mass, balance, and swingweight, their are infinite weighting combinations - some stiffer than others.

For example: Let's say you want to add 15g at 3&9 plus 5 grams in the butt to achieve a certain mass, balance, and swingweight. You could alternatively reach the same specs by adding roughly 8g at 12 plus 12g at the top of the handle.

The latter weighting will play much stiffer than the former, even though less weight is added to the hoop. Why? It's because of the mass added at the top of the handle, between the nodes.

If I want a racquet to play stiffer (at the same weighting specs), I move the hoop weight further north (which means less hoop wieght, but more counterweight between the nodes). If I want it to play more flexible, with more dwell time for more spin, I move the weight south more toward 3&9. It's what happens with the counterweighting that affects the stiffness.

Interesting. Verifies what I've experienced from experimenting on my own.

If this aspect of adding weight and it's effects on impact dynamics can't be measured by an rdc machine, it can surely be measured by some more sophisticated means.

[travlerajm]

Originally Posted by klementine79

Interesting. Verifies what I've experienced from experimenting on my own.

If this aspect of adding weight and it's effects on impact dynamics can't be measured by an rdc machine, it can surely be measured by some more sophisticated means.

It can be measured by vibration frequency.

[travlerajm]

Originally Posted by TheLambsheadrep

So a "performance #" of 385 is the better racquet quality to achieve...?

I do need to calculate swingweight, it's about the only thing I haven't done to my racquets. and my optimal MgR/I would be 21.0 since im right about 6 feet tall, but do you mean something else when you say "needs to be tuned to your personal swing?"

21.0 is just the starting point - you really need to find a wall and patiently tune the racquet while hitting against it to to get the most out of this.

Somewhere in these threads I posted a how-to on wall tuning, but I don't recall exactly where...
Edit:
http://tt.tennis-warehouse.com/showp...8&postcount=17

[TheLambsheadrep]

Originally Posted by travlerajm

21.0 is just the starting point - you really need to find a wall and patiently tune the racquet while hitting against it to to get the most out of this.

Somewhere in these threads I posted a how-to on wall tuning, but I don't recall exactly where...
Edit:
http://tt.tennis-warehouse.com/showp...8&postcount=17

ok. so from your "It's my belief that the optimal MR^2 zone of ~385 arises due to circumstance, because those pros that have both high swingweight (>350) and optimized MgR/I value (~21.0) tend to have racquets with MR^2 of about 385," you're saying you have to optimize MgR/I before MR^2...?

hypothetically, if you had to say that finding one was better in general, which would you choose (unless MgR/I and MR^2 are worthless without each other)?

[DeShaun]

Originally Posted by travlerajm

21.0 is just the starting point - you really need to find a wall and patiently tune the racquet while hitting against it to to get the most out of this.

Somewhere in these threads I posted a how-to on wall tuning, but I don't recall exactly where...
Edit:
http://tt.tennis-warehouse.com/showp...8&postcount=17

Dear Travelerjam,

I'm really sorry, I cannot do math. Learning calculus is on my bucket list though.

Would you please tell me where this racket falls on your spectrum:
27inch
416 grams
balance- 30.9cm from butt?

I'm 5'8"

Thank you
Sincerely,
DeShaun

[TaihtDuhShaat]

Deshaun- you will need to provide the SW to get a response for the MgR/I, but your racquet does check in at a very powerful 397 MR^2.

[corners]

Originally Posted by DeShaun

Dear Travelerjam,

I'm really sorry, I cannot do math. Learning calculus is on my bucket list though.

Would you please tell me where this racket falls on your spectrum:
27inch
416 grams
balance- 30.9cm from butt?

I'm 5'8"

Thank you
Sincerely,
DeShaun

Yeah, you need your swingweight and it needs to be precise, but once you have that you can use this spreadsheet posted yesterday by pbbrommer: https://docs.google.com/spreadsheet/...1b04ydWc#gid=0

[TaihtDuhShaat]

FWIW, I'm 5'10" and my perfectly tuned MgR/I tested across many racquets is ~20.93.

But, I use only head frames with their little extra buttcap flair, so my grip is ever so slightly choked up where the pinky ends a few mm's north of the end of the butt cap, compared to a wilson which is easier to hold at the end of the buttcap.

[dmcb101]

I have looked for the answer to this question and could not find it. I am about 5'8-5'9 and I have seen that my optimal number is about 21.2. A racquet that I am considering getting has a number that is 21.24. My question is, how much does a 100th of a number effect this whole pendulum stuff? Would 21.24 be fairly close or not that close? Just wondering the effect of the numbers. Thanks for the great information by the way. This thread literally opened my eyes to what I thought I knew about racquet customization so thanks!

[TaihtDuhShaat]

Every little bit has an effect when you are close the that tuned spot. 1/8 of a gram of lead transferred from the hoop to the upper grip can be felt. But, when you are within a 10th, that's close enough for practical purposes.