Shoulder Plane vs Arm Plane

[natureboy]

The only time the word gravity is used on that page is in the 8% thing-No justification or math or anything to show it is true.

Pretty sure this is not the topic anyway since raising the hands a few inches with a steeper plane is going to add roughly 0 MPH-I rounded it for you.

It is a conclusion from a complex model sparing the reader from reading the full derivation of the equations. Basically, gravity contributes a significant (but not huge) part of the double-pendulum swing model. If you model the left arm as a simple pendulum you actually get close to the same amount.

Take a real look at the whole site and see for yourself if he knows what he's talking about. He's a great guy, and I definitely trust his math.

It says gravity accounts for 8% of your swingspeed. That's gravity over the course of more than 6'. 2-3" won't make a difference.

6" relative height difference will give you about a yard free. Not much, but it might be statistically significant in terms of the two-plane preference on tour.

Granted, it looks like the small free gravity acceleration is not the primary reason for the PGA bias for two-plane. But it certainly isn't hurting.

So what do you think is the reason? Could it be as simple as just a teaching preference among instructors who taught the pros when they were young?

[Pretzel]

It is a conclusion from a complex model sparing the reader from reading the full derivation of the equations. Basically, gravity contributes a significant (but not huge) part of the double-pendulum swing model. If you model the left arm as a simple pendulum you actually get close to the same amount. Take a real look at the whole site and see for yourself if he knows what he's talking about. He's a great guy, and I definitely trust his math. 6" relative height difference will give you about a yard free. Not much, but it might be statistically significant in terms of the two-plane preference on tour. Granted, it looks like the small free gravity acceleration is not the primary reason for the PGA bias for two-plane. But it certainly isn't hurting. So what do you think is the reason? Could it be as simple as just a teaching preference among instructors who taught the pros when they were young?

It gives you a yard, IF you are 100% efficient in translating that gravitational potential energy into kinetic energy. Nobody is 100% efficient in that regard! which makes it a fairly moot point. I'm just saying the height won't make a difference in distance unless it causes a player to have a longer swing arc and more distance to accelerate in maybe. I've found my swing is become more of a two-plane swing as I begin to keep my hands in front of me. I was very much one plane (if you look at my swing thread) but the arms are getting steeper now just because the right elbow isn't going so far behind me. This could be part of it.

[iacas]

It is a conclusion from a complex model sparing the reader from reading the full derivation of the equations. Basically, gravity contributes a significant (but not huge) part of the double-pendulum swing model. If you model the left arm as a simple pendulum you actually get close to the same amount.

Take a real look at the whole site and see for yourself if he knows what he's talking about. He's a great guy, and I definitely trust his math.

I've read a bunch of his articles. Some are better than others. This one isn't even using his math. It's using Jörgensen's, and it assumes a double pendulum model.

Besides, this discussion is about a few inches. Since nobody makes a backswing where they don't raise their hands and arms a fair amount… that's appropriate. Claims of adding 9 MPH to my swing are not.

6" relative height difference will give you about a yard free. Not much, but it might be statistically significant in terms of the two-plane preference on tour.

I don't call one yard statistically significant. I also don't know that I accept the math that 6" = 1 yard.

Granted, it looks like the small free gravity acceleration is not the primary reason for the PGA bias for two-plane. But it certainly isn't hurting.

So what do you think is the reason? Could it be as simple as just a teaching preference among instructors who taught the pros when they were young?

I prefer not to engage in speculation, particularly since I don't know if we've agreed upon the definition of "two plane."

[natureboy]

I've read a bunch of his articles. Some are better than others. This one isn't even using his math. It's using Jörgensen's, and it assumes a double pendulum model.

Besides, this discussion is about a few inches. Since nobody makes a backswing where they don't raise their hands and arms a fair amount… that's appropriate. Claims of adding 9 MPH to my swing are not.

I don't call one yard statistically significant. I also don't know that I accept the math that 6" = 1 yard.

I prefer not to engage in speculation, particularly since I don't know if we've agreed upon the definition of "two plane."

I trust Dave Tutelman's math and analysis implicitly (http://www.tutelman.com/golf/DmtBioSportsTech.php). He's a P.E. and worked at Bell Labs. He has passions for science and golf and shares both freely on his website. What's most impressive is that even with all his knowledge and experience using physics and complex calculations every day as a professional, he remains open to exploring new ideas and information even if it seems to disagree with his current model. That's a scientific mindset.

Jorgensen's math is the 'source paper' that other models have been built on and refined from. That's why it's referenced on Dave Tutelman's page. The basic model hasn't been fundamentally revised in quite a while. Refined, yes.

I agree 1 yard is small. That's why I don't consider the hand height the cause for why there may (or may not) be a bias to 'two-plane' positions at the top on tour. I was responding to the point that gravity added 'nothing' to the swing.

That's a good point about the definition...what is your definition of two-plane? If you show pictures for comparison, I think it would be most accurate to compare swings with the same length club at the top. Most pros swing shorter clubs on a shorter arc and the hands don't get as high as with the driver which is usually the 'full' arc.

Adam Scott with driver down the line (vs. the iron swing shown) looks what I would term distinctly two-plane - slightly more so that Rory (though the sweater obscures Rory's upper right arm). For me 6" is about my upper arm length which if I stayed very 'connected' at the top would make my position more akin to 'Five Lessons' Hogan or Kuchar (what I consider one-plane) and if I 'elevated' the hands would make my upper right arm more horizontal akin to Scott at the top with driver. This distinction is why I didn't consider my posts about hand height to be OT.

I agree the 'two-plane' idea is more of a continuum than a simple yes/no distinction so the OP point about what's seen on tour is worth questioning.

My personal eyeball test is the degree of deviation of the angle of the long axis of the upper right arm from the horizontal plane of the shoulders, which usually seems to be complemented by a deviation in the left arm angle from the horizontal shoulder plane (when viewed down the line). For me, anyone above the Hogan / Kuchar position are 'two-plane'. You can have a very upright 'swing plane' with a more 'one-plane' arm position at the top (if you have significant hip bend) and you can be super upright in swing plane and very two-plane with the arms like Bubba (some swings his L arm looks nearly vertical).

[iacas]

I agree 1 yard is small. That's why I don't consider the hand height the cause for why there may (or may not) be a bias to 'two-plane' positions at the top on tour. I was responding to the point that gravity added 'nothing' to the swing.

Have you managed to prove a two-plane bias?

I agree the 'two-plane' idea is more of a continuum than a simple yes/no distinction so the OP point about what's seen on tour is worth questioning.

Of course it's a continuum.

I don't think a yard is worth talking about. There are likely many other reasons why a player would be better up with a deeper or slightly more upright swing.

[jclark]

Two things: first, I would not change from one model to another for 1 yard; nor would I say one is more superior than the other. Secondly, the further the hands travel on an arc the more speed you should get, all things being equal in your swing. I don't think pros have a preference, their bodies and swing styles and mechanics probably choose oNE or two plane for them.