The Backswing Ends at ~P2

[iacas]

8 hours ago, pinseekingdreams said:

Wondering if this sort of explains the idea that the first I think few inches of the backswing are the most important part and set up the rest of the swing? I think Nicklaus said that, and maybe Butch Harmon.

No, it's not really the same thing. Setup and the backswing are important, but this is talking about when you start to apply force in the downswing direction and for how long you apply force in the backswing direction.

[Zeph]

Very interesting video. I would never imagine that you already start slowing the club down at that point.

The club is obviously still moving in the "backswing direction", and he's still using force to get it there. Does this happen because most of the hinging action starts at that point? The hands are moving back and up, but the clubhead has to move farther than the hands to get the wrist hinge done. By still moving the handle back and up, but at the same time hinging the wrists, the hands apply torque in the other direction to allow the club to hinge properly.

The clubhead travels more than a quarter of a circle, while the hands travel less than a quarter of a circle.

[iacas]

5 hours ago, Zeph said:

The club is obviously still moving in the "backswing direction", and he's still using force to get it there. Does this happen because most of the hinging action starts at that point?

If I push a ball, does it stop rolling when I stop pushing?

5 hours ago, Zeph said:

The clubhead travels more than a quarter of a circle, while the hands travel less than a quarter of a circle.

The hands hopefully travel more than a quarter of a circle (but less than a half).

It's a little bit of feel vs. real here, but also…

[Zeph]

1 hour ago, iacas said:

If I push a ball, does it stop rolling when I stop pushing?

No, but we are lifting the club and gravity is constantly trying to pull it back down. I haven't swung a club to get a feel for it, but I didn't imagine the club had enough velocity at that point in the backswing that you needed to pull the brakes already there. I also don't know how fast he swung the club back, which could make a difference on where the torque switched. I didn't quite grasp the different torque planes or how that is applied to how I interpret "torque". I'm not saying he's wrong, just trying to understand what is happening. I'll watch the video again a few times.

1 hour ago, iacas said:

The hands hopefully travel more than a quarter of a circle (but less than a half).

It's a little bit of feel vs. real here, but also…

I meant from the point where the torque turns positive, just before P2. Feel is difficult enough, but in this case "real" is also difficult to comprehend.

[iacas]

The club and arms have momentum. Hence the feel that he’s not doing anything after 2.

[Ty_Webb]

I watched the Cooper video. It seems to me that he's talking about his pressure trace is done moving to the right by P2, not that he's no longer applying an upward force to the club after P2. Am I misunderstanding that? I know that I tend to hit it better if I focus on having my weight shift left before my backswing is "over" (i.e. P4 I think). I'm not sure it's as early as P2, but then I don't think I'm getting 95% of my pressure on my trail foot by P2 either. I think I max out about 75%. On a separate note, as an habitual slider, the stuff about pushing back again with the lead side is golden.

[iacas]

19 minutes ago, Ty_Webb said:

I watched the Cooper video. It seems to me that he's talking about his pressure trace is done moving to the right by P2, not that he's no longer applying an upward force to the club after P2. Am I misunderstanding that?

Having talked with him and others briefly, yes, a bit. Other long drive guys have said similar things.

[Zeph]

1 hour ago, Ty_Webb said:

I watched the Cooper video. It seems to me that he's talking about his pressure trace is done moving to the right by P2, not that he's no longer applying an upward force to the club after P2. Am I misunderstanding that? I know that I tend to hit it better if I focus on having my weight shift left before my backswing is "over" (i.e. P4 I think). I'm not sure it's as early as P2, but then I don't think I'm getting 95% of my pressure on my trail foot by P2 either. I think I max out about 75%. On a separate note, as an habitual slider, the stuff about pushing back again with the lead side is golden.

I can't quite get my head around it, but I suppose you can apply a force to an object in one direction while applying torque in another, which is a rotational force. One force is lifting the club up while a rotational force at the same time apply torque. And the reference is in plane.

Maybe this is just outside my understanding of physics.

[Ty_Webb]

40 minutes ago, Zeph said:

I can't quite get my head around it, but I suppose you can apply a force to an object in one direction while applying torque in another, which is a rotational force. One force is lifting the club up while a rotational force at the same time apply torque. And the reference is in plane.

Maybe this is just outside my understanding of physics.

I do remember reading something that Sasho Mackenzie said - that if you have a fast backswing, you need to apply a force back towards the ball that is substantial during the backswing to slow the club down and stop it. The faster the club is moving up, the more force that you need to apply to stop it, which then means you are applying more force in subsequently accelerating the club back to the ball. All else being equal, that will result in more clubhead speed at impact. In order to get the club to stop at some point, you have to decelerate it, which involves applying a force in the opposite direction. That much is self-evidently true. I am surprised that the decelerative forces start being applied as early as P2, but it's certainly possible. I would not be surprised to find out that the long drivers have to feel like they start applying that force at P2 in order to actually start applying it a little further up in the backswing. 

It makes sense that the backswing force application stops well before the club does - it has to. But gun to my head, I would have guessed that happens around P3, not P2.

[billchao]

1 hour ago, Ty_Webb said:

I do remember reading something that Sasho Mackenzie said - that if you have a fast backswing, you need to apply a force back towards the ball that is substantial during the backswing to slow the club down and stop it.

That makes a lot of sense to me. Unfortunately, I’m exceptionally bad at it so I’ve learned to slow down my swing at the top by slowing down my backswing and I have to constantly remind myself not to get “too quick.”

1 hour ago, Ty_Webb said:

I am surprised that the decelerative forces start being applied as early as P2, but it's certainly possible.

It could just be a function of time required to get those forces in the opposite direction, especially since the long drive guys are generating greater forces to begin with. It’s not like we can get the club going back/up and then immediately get it to turn the opposite direction without momentum.

[Ty_Webb]

7 minutes ago, billchao said:

It could just be a function of time required to get those forces in the opposite direction, especially since the long drive guys are generating greater forces to begin with. It’s not like we can get the club going back/up and then immediately get it to turn the opposite direction without momentum.

That is true. If you watch Kyle Berkshire swing at full speed, his clubhead speed at P2 is probably higher than mine at impact. He really whips it back fast. In theory though, assuming that you can apply the same force towards the ball as you can away from it, if you start at zero, accelerate it away for half the backswing and then towards the ball for the other half, you should hit zero at about the right spot (assuming gravity is effectively negligible given the size of the forces otherwise applying). I think the biggest issue is you can't switch from fully in one direction to fully in another instantaneously, so that change has to happen over a period of time. The faster the club is going, the longer that period will need to be in terms of distance of the club travelled. So in retrospect it could very well be that they need to start to switch at P2 to get that to happen. So in terms of Ps, we'd have max acceleration away from the ball from P1 to P2, then it would start to switch at P2, hit basically zero at around P2.5, then hit max acceleration towards the ball about P3, so the club comes to a stop at P4, before then accelerating down towards the ball all the way to P7. The effort towards the ball I'd think probably actually stops or slows down around P6 when the hands start to really slow down and then the levers apply that speed to the clubhead between P6 and P7 without a huge amount more effort from the player towards the ball at least. I think the hand forces are basically applying straight back up towards the player's center at that point and that force causes the club to rotate down towards the ball. Fun thing is at that point, the hands can be moving up and in while the clubhead is moving down and out, so your hand path can be well left and still generate a club path that is square or to the right.

[phillyk]

Some graphs from Dr Kwon’s research. I have these posted up at my golf school. 

Dark Blue line is arms. You can see it maxes angular velocity in between p2 and p3, in this graph.

 

Right foot pressure maxes at approximately the same time. These graphs are an average of the pros he has measured. 

[Ty_Webb]

Thanks phillyk - that I think ties reasonably well to when the intent would be to stop. It's also possible that long drivers would have their stuff shifted a little from tour players who have different goals in their swings than hitting it as hard as possible.

[iacas]

6 hours ago, Ty_Webb said:

I do remember reading something that Sasho Mackenzie said - that if you have a fast backswing, you need to apply a force back towards the ball that is substantial during the backswing to slow the club down and stop it. The faster the club is moving up, the more force that you need to apply to stop it, which then means you are applying more force in subsequently accelerating the club back to the ball. All else being equal, that will result in more clubhead speed at impact. In order to get the club to stop at some point, you have to decelerate it, which involves applying a force in the opposite direction. That much is self-evidently true. I am surprised that the decelerative forces start being applied as early as P2, but it's certainly possible. I would not be surprised to find out that the long drivers have to feel like they start applying that force at P2 in order to actually start applying it a little further up in the backswing. 

It makes sense that the backswing force application stops well before the club does - it has to. But gun to my head, I would have guessed that happens around P3, not P2.

If you tell someone to make a half backswing, they invariably make what amounts to a decent full backswing (just maybe a little shorter than their over-swinging really long backswing). So, I also think a part of this is what feels like P2 is often almost P3.

[saevel25]

5 minutes ago, iacas said:

If you tell someone to make a half backswing, they invariably make what amounts to a decent full backswing (just maybe a little shorter than their over-swinging really long backswing).

Or, tell me to make a swing that goes to P2 🤣

Yea, that makes sense.