Measuring Closure Rate and Grip Roll or Twist on GEARS

[Warlock]

So which is more meaningful  or is ROC meaningless ( see my drawing below)?

1. Rate Of Closure relative to path

2. Rate Of Closure relative to target 

3. Rate of Closure measured in degrees/sec

4. Rate of Closure measured in degrees/distance

 

 

Edited February 18, 2022 by Warlock

[Ty_Webb]

On 2/16/2022 at 1:06 PM, iacas said:

Have you considered the possibility that the clubface hitting the ball could affect the "clubface" in that moment? As you know a toe hit will open the face even though the grip end could still be twisting the other direction in that moment.

I urgently need to see high speed video of this happening. I've seen video of pros hitting it solidly and it definitely flexes somewhat, but this reminds me of that probably fake video of the golf ball bouncing off a steel plate. It's so extreme my mind is basically refusing to believe it without photographic evidence. 

[iacas]

45 minutes ago, Warlock said:

or is ROC meaningless

I'm going with that, yes.

As a bunch of videos and studies will tell you:

• There are accurate players with high rates of closure.
• There are accurate players with low rates of closure.
• There are long hitters with high rates of closure.
• There are long hitters with low rates of closure.
• There are good players with high rates of closure.
• There are good players with low rates of closure.
• There are bad players with high rates of closure.
• There are bad players with low rates of closure.

48 minutes ago, Warlock said:

4. Rate of Closure measured in degrees/distance

I prefer that method, because if you took Dustin Johnson's swing and slowed it down 10%, if you do it in °/s it's 10% less… despite having the same "positions in space." Higher swing speeds have higher "°/s" "rates of closure" simply by the nature of their higher swing speeds.

The GEARS video you showed above showed Rickie and Blixt.

2 minutes ago, Ty_Webb said:

I urgently need to see high speed video of this happening. I've seen video of pros hitting it solidly and it definitely flexes somewhat, but this reminds me of that probably fake video of the golf ball bouncing off a steel plate. It's so extreme my mind is basically refusing to believe it without photographic evidence. 

We could probably record one with a 960 FPS camera and compare it to the resulting GEARS video, but I don't know what to tell you except that GEARS is research grade for its club data. It's exactly what you would have seen from that shot.

There's a decent chance I can do this for you at some point because… we wouldn't need to get in the entire suit. We'd just need to show the clubhead swinging, no body data.

[Ty_Webb]

37 minutes ago, iacas said:

We could probably record one with a 960 FPS camera and compare it to the resulting GEARS video, but I don't know what to tell you except that GEARS is research grade for its club data. It's exactly what you would have seen from that shot.

There's a decent chance I can do this for you at some point because… we wouldn't need to get in the entire suit. We'd just need to show the clubhead swinging, no body data.

I'm not saying I don't believe it. I'm saying it's so mindblowing that I want to see video of it happening. I know GEARS is hugely impressive and would read this correctly. That clubface looks like it's twisting 90*. 

My coach was telling me that a 110mph driver swing, the force the club is pulling you with is around the equivalent of 100lbs. It's fascinating to me that it's so high and doesn't really ring true given how heavy 100lbs is and how little I fear the club coming out of my hands, but the force needed to twist a clubhead that much must apply an incredible force on the hands. I know sometimes I mishit shots and the club twists in my hands somewhat. I guess now I know why! 

Would it change much depending on the flex of the shaft? I'm kind of assuming that the shaft in the tweet was a L flex graphite shaft or some such. Would X-stiff steel react differently? I assume torque ratings would impact how much it twists as well. Presumably the stiffer the shaft too, the more forceful the twist applied to your hands by a toe strike would be. You'd feel nothing if it was a piece of string, but everything if it was rebar.

[iacas]

14 minutes ago, Ty_Webb said:

My coach was telling me that a 110mph driver swing, the force the club is pulling you with is around the equivalent of 100lbs. It's fascinating to me that it's so high and doesn't really ring true given how heavy 100lbs is and how little I fear the club coming out of my hands

It does, yes, but you can obviously lift more than 100 pounds, or pull on a rope in a tug-of-war with more than 100 pounds…

14 minutes ago, Ty_Webb said:

but the force needed to twist a clubhead that much must apply an incredible force on the hands. I know sometimes I mishit shots and the club twists in my hands somewhat. I guess now I know why! 

Yes, plus a lot of the force is almost a "pulse" that's absorbed by the shaft, the grip, even the flesh on your hands rather than the "bones" or actually moving your hands/wrists.

14 minutes ago, Ty_Webb said:

Would it change much depending on the flex of the shaft? I'm kind of assuming that the shaft in the tweet was a L flex graphite shaft or some such.

At that swing speed? No. Ryan plays Nippon N.S. Pro Modus Tour120 X shafts.

Let's get back to topic (if there's any more to discuss here, that is).

[GolfLug]

1 hour ago, Ty_Webb said:

My coach was telling me that a 110mph driver swing, the force the club is pulling you with is around the equivalent of 100lbs.

Only if you try to freeze it mid swing. Your coach must not account for inertia. 

[billchao]

2 hours ago, Ty_Webb said:

I urgently need to see high speed video of this happening. I've seen video of pros hitting it solidly and it definitely flexes somewhat, but this reminds me of that probably fake video of the golf ball bouncing off a steel plate. It's so extreme my mind is basically refusing to believe it without photographic evidence. 

https://youtu.be/6dG9hb3_blo

YouTube doesn’t allow embedding of this video for some reason.

[iacas]

59 minutes ago, GolfLug said:

Only if you try to freeze it mid swing. Your coach must not account for inertia. 

No, it's pulling outward from your hands with 100 pounds of force.

[Big Lex]

On 2/18/2022 at 9:32 AM, iacas said:

• There are accurate players with high rates of closure.
• There are accurate players with low rates of closure.
• There are long hitters with high rates of closure.
• There are long hitters with low rates of closure.
• There are good players with high rates of closure.
• There are good players with low rates of closure.
• There are bad players with high rates of closure.
• There are bad players with low rates of closure.

I find this really interesting and a little surprising. 

What data set are these statements based off? I assumed it might be the GEARS data for tour pros, but then you mention "bad players" and so I assume there must be some amateurs in your data set. 

It just seems intuitive that - all other things being equal (which we know they never are) - a swing where the face is rotating slower or through less of an arc should produce more accurate shots over time (less dispersion). Golfers aren't robots and don't have identical ball position on EVERY swing, and so it's reasonable to assume they might catch the ball at a slightly different point in their arc in different swings. The more variance there is in face angle at different points on the arc, the greater the differences should be in shot direction. 

But I guess not 🙂

I suppose things like a good (and consistent) club path and face angle at impact have a much, much greater effect on the result of the shot than any variance which might be induced by differences in face closure rate.  

I mention this because I once had a golf lesson from a prominent teacher who bases one part of his teaching system on the premise that a certain grip, hand action, and release produces more accurate striking, for multiple reasons. One reason he cites is his belief that this pattern creates less face rotation in the swing. This is NOT the main reason he teaches this grip and release; he teaches them because he believes his method creates a swing which is more "natural," mechanically simpler, and therefore easier to execute consistently. But he also talks up the face closure aspect of it. 

 

[iacas]

2 hours ago, Big Lex said:

What data set are these statements based off?

A few thousand golfers across ability levels. Not just GEARS data, but ENSO data, etc. Fujikura and PING would tell you the same things. GEARS folks can tell you the same thing(s).

2 hours ago, Big Lex said:

It just seems intuitive that - all other things being equal (which we know they never are) - a swing where the face is rotating slower or through less of an arc should produce more accurate shots over time (less dispersion).

I've said that "lag happens" just as a matter of sequencing, and the same is true of grip roll and/or face control. It "happens," it's not often something you specifically work on.

That's not to say I don't work with people who flip/roll incorrectly… just that some people with stronger grips or a different manner of "releasing" the club (still dislike that term) will have different rates. If it's "natural" and a good fit for you, you can hit it straight and/or far even if it's a higher rate/distance.

2 hours ago, Big Lex said:

But I guess not 🙂

You're missing that golfers aren't robots… which is a positive, too, in that they can adapt.

2 hours ago, Big Lex said:

I mention this because I once had a golf lesson from a prominent teacher who bases one part of his teaching system on the premise that a certain grip, hand action, and release produces more accurate striking, for multiple reasons. One reason he cites is his belief that this pattern creates less face rotation in the swing. This is NOT the main reason he teaches this grip and release; he teaches them because he believes his method creates a swing which is more "natural," mechanically simpler, and therefore easier to execute consistently. But he also talks up the face closure aspect of it. 

I've undoubtedly taught lessons which reduce the amount of face roll, but most of those lessons fit into one of two categories (or both):

• Golfers who square the face up "improperly" by flipping/rolling the wrists in a way that doesn't help them strike it cleanly (often with little to no shaft lean, etc.).
• Golfers whose body stalls out so the face rolls hard through impact and early into the follow-through. Now, often these numbers don't change much before impact, but they do after impact, and so it's a byproduct of simply a better use of the body.

In both cases, the change to the face roll is almost a byproduct, not the end goal.

I suppose a third thing that would change this is just someone with a horrible grip or someone who twists the face wide open during the early downswing. Often these people don't even square the face up, so sometimes these lessons result in increasing the rate of closure/grip roll through the delivery stage.

[Warlock]

On 2/15/2022 at 4:07 PM, iacas said:

@Warlock, two things before I get into this…

• This isn't something I've had to use with students in GEARS, and honestly isn't something I expect to use within GEARS with students, so I haven't looked into it much. If the numbers in GEARS are completely useless because it turns out that they're measuring the rotation of the shaft relative to Alpha Centauri's orbit around Ursa Major, it wouldn't really matter much to me. 😄
• I'll ask a few people who should know, and put it out for discussion amongst GEARS owners, and will report back. My answers below represent my best "knowledge" at this point.

Let's try to be picky about the words we use, etc. "Closure rate" alone can mean a lot of different things. Closure relative to what? If we're talking about the clubhead, are we talking relative to the target line or the instantaneous path of the swing?

The answer I've gotten, as I've said, is this:

• Grip roll is measured as the twisting around the shaft. So if you look at the butt end of the club, it's twisting 3:00 to 12:00 or vice versa.
• Clubface closure is relative to the path.

I think this video segment shows this relatively well (should start at 7:30):

I believe GEARS measures the "face" as perpendicular to the yellow line, which is basically an extension of the bottom groove for the "closure rate." In other words, if the face is going to hit the ball with a 0.0° path and the perpendicular to the leading edge is 0° as well, but some "x" time before when the path was 5° right but the face was 10° right, then that would be 5°/x rotation (where, again, x is some unit of time).

In the video above, the one golfer is 43° open at 6, which let's assume is 40 milliseconds before impact, and we'll assume he hits the ball square to the path (he almost surely doesn't, but he's probably close): 43/0.04 = 1075°/second.

Well… Taking this in parts, and addressing the "could be decreasing" part first: I have to believe you understand that a clubface can still be "closing" but doing so at a slower speed. If something is "closing" at one point at (to make up a number) a billion degrees per second, but then slows down to closing only 10 million degrees per second, it's still closing. Just not as quickly.

Sasho's article also says:

The club is swung down and around the body on the forward swing, which presents the Inclined Plane knob. Turning this knob to zero would result in moving the clubhead in a vertical plane like a Ferris wheel (0° from vertical). At a driver speed of 90 mph, an Incline Plane knob turned up to 30° from vertical (a steep move through impact) contributes about 800 °/s to RoC. Cranking the knob up to a relatively flat 45° from vertical, increases the contribution to 1200°/s. There may be reasons to change the pitch of your swing, but reducing RoC shouldn’t be one of them. Tour players tend to have relatively similar vertical swing planes with driver (40° to 45° from vertical) and most amateurs are too vertical already.

Which… doesn't really seem to jive with the numbers I'm seeing from, for example, this multiple-time major winner:

GEARS tells me that at A6 and A7, the numbers are (rounded to integers):

• A6: 775°/sec grip roll, 512°/sec closure rate, 27.4 rpm closure rate^
• A7: 1745°/sec grip roll, 514°/sec closure rate, 431 rpm closure rate^

^ Why are these numbers different?

BTW, the path here was 1.86° out with a face 2.73° open. The frame here is just before impact.

The fact that 512° and 514° are similar, but 27.4 rpm and 431 rpm are wildly different, but both are listed as "closure rate" makes me wonder about a lot of things here. 😛

The thought just occurred to me that maybe the "rpm" one is the shaft rotational rate and the "°/s" is the clubface's rotational rate?

That's because: CCV = HTV sin (θ) + SPV cos (θ) where θ is the Lie Angle. Again, it's the frame of reference and how you're measuring it.

This assumes they're using the same frame of reference for "clubface closure."

So… handle twist velocity (HTV) plus

Since sin(58°) is ~0.84, you're adding two big numbers together. 1075°/second HTV adds about 911 RPM closure rate if measured that way, plus the angular rate of speed of the clubhead which is going to be quite high itself.

Yes, it says:

Closure Rate is a measure of the rotation of the club face as it approaches the impact point. This measurement is calculated relative to the club’s path.

Specifically, an angle is measured between the face of the club and the path of the club as shown. Closure Rate is the rate of change of this angle measurement (in degrees/second) of the club’s face relative to the club’s path.

That says to me what I said above: it's the face angle relative to the path. What I'm not 100% certain of is whether it's, say, the spin axis/D-plane or just the leading edge normal relative to the path.

There's also this, in the new "Graphs" section (the graphs were re-done in the latest release). This shows a peak "Taylormade Closure Rate" of nearly 2780°/s.

I'm not sure what you mean about an "angular measurement" versus a "rate." If you have an angular measurement that's changing over time, that's an angular rate of change.

That's just defining when it's measured. It only measures it for the downswing. See the graph above. The dotted line is the change of direction of the club head.

I believe that's about it.

I don't think you should call it the "D-Plane" because it's more like the actual path, and the leading edge/shaft normal (perpendicular to the leading edge and the shaft). The D-Plane is normal to the FACE, not the leading edge/shaft. You could add or take off loft relative to the path and the "closure rate" would be affected a bunch, so maybe stop saying "D-Plane."

---

So, it seems like you've arrived at the same conclusion as what I said up above:

I said "plane" but the plane is the tangent to the path at that point, so that's what I was saying.

---

From the video up above:

To the last image, I will add this: GEARS doesn't continue to measure grip roll past impact, so I'm not sure if they're measuring the rotation from shaft parallel to shaft parallel, or if they're extrapolating it somehow.

---

All that said, my questions are:

• Why are the RPM and the "closure rate" marked the same? Hmmm, maybe it's the Cheetham/Sasho measurement for clubhead closure rate: 431 rev/min * 360°/rev * 1 min/60 sec = 2,586°/sec. That's pretty close.
• Actually that might be my only question. Maybe in GEARS the "°/sec" is showing relative to the path or instantaneous plane, and the rpm is showing relative to the target line.

I think that's all the questions I have now.

 

Iacus, 

Did you ever find out what GEARS metric  'Closure Rate' in rpm was measuring?  Is it different to 'Closure Rate' in degrees/sec?

[iacas]

1 hour ago, Warlock said:

Iacus,

Who dat? Also…

1 hour ago, Warlock said:

Did you ever find out what GEARS metric  'Closure Rate' in rpm was measuring?  Is it different to 'Closure Rate' in degrees/sec?

Heading out to soccer, but pretty sure I answered it up above.

IIRC, one is the grip roll rate while the other is the face closure rate to the path.

[Warlock]

3 hours ago, iacas said:

Who dat? Also…

Heading out to soccer, but pretty sure I answered it up above.

IIRC, one is the grip roll rate while the other is the face closure rate to the path.

Oops sorry iacus (typo error).

Below is what you said in a previous post and wondering whether you were able to confirm if 'T_Closure Rate' measured in rpm was actually the shaft rotational rate?  Also, when you say, 'shaft rotational rate', do you mean the actual rotation of the shaft about the longitudinal axis of the shaft?

"The fact that 512° and 514° are similar, but 27.4 rpm and 431 rpm are wildly different, but both are listed as "closure rate" makes me wonder about a lot of things here. 😛

The thought just occurred to me that maybe the "rpm" one is the shaft rotational rate and the "°/s" is the clubface's rotational rate"

 

 

 

 

[Warlock]

Hi iacas

You actually mentioned the below so were you correct about closure rate in rpm being measured relative to the target line?

"Why are the RPM and the "closure rate" marked the same? Hmmm, maybe it's the Cheetham/Sasho measurement for clubhead closure rate: 431 rev/min * 360°/rev * 1 min/60 sec = 2,586°/sec. That's pretty close.
Actually that might be my only question. Maybe in GEARS the "°/sec" is showing relative to the path or instantaneous plane, and the rpm is showing relative to the target line."

 

Edited July 16, 2022 by Warlock

[iacas]

5 minutes ago, Warlock said:

iacus

Seriously?

[Warlock]

8 minutes ago, iacas said:

Seriously?

Apologies again - old age I'm afraid and I've corrected my post.

Edited July 16, 2022 by Warlock

[iacas]

5 hours ago, Warlock said:

Apologies again - old age I'm afraid and I've corrected my post.

I'll link to it again: https://thesandtrap.com/how-to/mention-members/.

And yes, I'd already answered this, but I'll do it again:

Quote

The grip roll is about the axis of the shaft, and is just the twisting of the grip from 12:00 to 3:00 or vice versa.

The "closure rate" that's measured in °/sec is the leading-edge/shaft normal (perpendicular to both the leading edge and shaft) relative to the path or instantaneous plane of the clubhead.

• The Grip Roll is as I said above. Twisting around the axis of the shaft or grip.
• The °/sec Closure Rate is the GEARS "relative to the path" measurement.
• The rpm Closure Rate is the TaylorMade Closure Rate, because… 431 rev/min * 360°/rev * 1 min/60 sec = 2,586°/sec, which is pretty close to the roughly 2780°/sec I get in the graph for TMCR.

The TMCR in °/sec more closely lines up with the numbers that Phil and Sasho are talking about.

[Warlock]

4 hours ago, iacas said:

I'll link to it again: https://thesandtrap.com/how-to/mention-members/.

And yes, I'd already answered this, but I'll do it again:

Many thanks again