Time for OEMs to start publishing MOI and CoG with driver releases

[MattM97]

No, no, no. Let's get this straight, we all get it, you're the one who doesn't get it. If you don't like it then please feel free to boycott WRX and all OEM's who don't provide the details you want.

[getitdaily]

Well this response was a bit over the top. But carry on. Love how discussion turns...

[Stuart_G]

Except most of the golfing public doesn't have a clue as to what their face impact tendencies are. And without that, the c.g. location info is useless at determining any type of bias to expect from the head.

On top of that it would also make the c.g. location seem to be a lot more important in the shot shape control than it really is resulting in the other more important factors for each player being overlooked or even ignored.

[Howard_Jones]

We need 3 if we want to get something out of it.

Vertical center of gravity on both the vertical and horizontal axis, and Rearward center of gravity, and thats makes 3 measurements of the head, and we also know that shaft properties is part of it where a "high launch" shaft who has a soft tip to mid section will allow more twisting (vertical) than a Low launch tip and mid stiff profile.

[getitdaily]

I believe you're insinuating that path and face to path are more important than CoG and gear effect. If so, I wholeheartedly agree.

However, as one gets more consistent with those 2 factors, aren't CoG and gear effect then a key element to consistency in shot shape?

Not sure I want to debate shaft characteristics since, imo, that's a bit more difficult to understand and those characteristics can't be changed without a new shaft.

[getitdaily]

Now we're talking...so let's say a guy has a shaft he really gets along with. But the guy wants a new driver. If shaft were eliminated as a variable (I like my shaft...) then CoG would tell that golfer something reasonably significant....?

[getitdaily]

Maybe I should change the thread title to "gear heads unite"...

[Howard_Jones]

Testing i did in my studio was all done with real players, so they become kind of "un-scientific" since we never have the same impact conditions, and i did nothing to analyze the numbers and split them depending on this measurements. i saw a pattern that for each 1/8" we moved impact up or down on the face, spin levels changed by average 240 rpm, and thats good to know, but i cant say that a change of VCOG by 1/8" makes the same difference, even if that might sound logical., since that becomes a question of RCOG and MOI plus shaft properties.

The reason is that my numbers comes for several different head models, several different lofts, and different shafts, and different impact conditions like path, face angle and angle of attack, so all i found was a pattern for how vertical gear effects works, but not with a mathematical constant, but i use the number 240 rpm for each 1/8" since thats the average of the numbers ive collected.

This illustration explains it better, but again, there is not even a constant for face roll from driver to driver, they vary, and by that "actual loft", so this illustration is only useful to explain "how it works"...

The concept ive used here is the same as USGAs ball cannon test for drivers where the head is fixed, and the ball is shot against the face. Depending on impact height, we should see a pattern on return values like this:

[Stuart_G]

If you want to talk consistency of the results, it's the consistency of the delivery of the head into impact and the face impact that's at the core of inconsistent results. The gear effect only acts as a scaling factor for just the inconsistencies in the face impact location. It has no effect on other inconsistencies in the delivery. And for those with inconsistent face impact, the MOI is generally going to be more of a factor than the c.g. location in reducing the dispersion in the results.

 

So the two extremes to the consistency question would be:

1) You have someone with very consistent delivery, and very consistent face impact, than the amount of gear effect will also be consistent regardless of where the c.g might be. It might have a small effect on the consistent shot shape but unless it's a consistently bad face impact location, it likely wont be all that much.

2) You have someone who has very inconsistent face impact location, than they are very likely also going to be just as inconsistent with other aspects of the delivery. In some cases the gear effect will make the overall ball flight worse but in some other cases the gear effect can help. e.g. open face to path combined with a toe side miss means less of a slice than someone with open face heel side miss inconsistencies. These people are going to be much better served by finding the club specs that will help improve the face impact consistency or delivery consistency (playing length, shaft weight, swing weight, grip size, face angle, etc..) and maybe moving to high MOI head in general - than they would worrying about the details of the c.g. location.

 

[crapula]

The information should not only be available but each manufacturer should explain how they measure/ gather such information.

Like what Callaway did this year when they decided to measure club lengths different. They didn't have to explain, but they did.

True loft, head weight, lie, COR test, face angle, etc... eventually some manufacturer will allow the option for hand picked heads to the public from their website. The demand just has to get high enough, I think it will, but it might take a while.

It would be great if manufacturers actually swing weighted clubs with custom specs and included SST pureing as an option (or just did it every time free of charge).

The options get better and better every year, hard step, soft step, + wraps, + wraps under lower hand, grip stretched -1/64, etc.

 

To anyone saying that the public majority doesn't know any better, that's irrelevant, they can just buy the standard stock option. It would be nice to have the option to buy very specific specs. You can go to best buy and buy a stock computer or you can buy a custom computer or you can build it yourself. Just because the majority doesn't know about all of the customization's isn't a reason to limit the advanced consumer. From a business perspective it may not be cost effective either, but sometimes to get ahead or stay ahead of the rest you need to incorporate a loss leader strategy.

 

[getitdaily]

Bingo! You get it!

[Howard_Jones]

What you are asking for have been available from Custom Club makers as long as i can look back in time, so you have that option, but insist that it become a option from them who lives by selling clubs in large quantum....its like asking McDonals to set of a Gourmet option because you dont want to go to a real Gourmet restaurant.

[crapula]

Yeah, that's great for custom club makers. Manufacturers will continue to offer more options as time goes on.

I'm not insisting, it would be nice if they did. Damn, can't anyone ever ask for anything and dream without being crapped on here?

 

[getitdaily]

Agree again on delivery and impact location.

I do come at this from your perspective #1. I am very, very consistent in impact location and delivery. I am lucky enough to have access to a launch monitor just about as much as I'd like. I have tested my SIM and the affect of moving weight around. I was able to see that moving CoG heel/toe added or reduced sidespin by a couple hundred rpm.

For adjustable weight drivers (heel/toe adjustability), CoG doesn't matter as much, imo. But a driver like SIM MAX, Speedzone, Mavrik...CoG location would be important for a knowledge person to know as part of the buying process since CoG movement is basically non-existent.

[Howard_Jones]

Its fine with hopes and dreams, but be realistic, its not like you cant find what you want, but you want find it where you wants to find it, thats the only issue you have here, the next is, what are you willing to pay for the difference? Custom Club makers pricing is often seen as "overpriced" so you are asking for more, and you can have it, but many want pay for it, but the option is there....

Yes we dont have to go back more than 10-12 years in time, before the options from OEMs was limited to play lengths, Loft and lie angle and grip size, so they have made huge progress in the direction of "custom" with tons of shafts options and adjustable hosels, but never forget that their concept is volume sales, so even a simple thing like shaft testing for FLO or PURE would slow the production line so much they want be able to make the margins they need. If there was something we should have more insight on, its their standards and tolerances, but they keep it for themself, and thats why there is a marked for Custom Club makers who offers "true specs" and like some customers demand it to be.

[getitdaily]

I love what you bring to the forums! You single handedly helped me gain a significantly better understanding of the impact of gear effect and CoG.

[Howard_Jones]

Thanks but im about to get old and rusty, and development goes on without me being able to keep myself updated on "the latest", but if we talk the basics for "how it works", that want´chance since thats pure physics and has been known for decades, and before the invention we see today was possible to make due to lack of "modern materials". Those of you who actually wants to know the physics behind club tech should buy a book thats now almost 20 years old, written by Richard Grieg and Dr. Frank Werner. Thats one of the most important books ive been reading to get the understanding i have. Lots of the stuff they are writing about and explain was theories written down in the 60s, before we had graphite shafts and titanium, but they did the numbers for how it would work, so i been smiling every time some OEM have launched something "new", like the square heads from Callaway and Nike with High MOI some 12-14 years back. Its nothing new under the sun, and we want see anything thats not described in that now 20 year old book since the laws of physics has not changed since then.https://www.amazon.com/Clubs-Really-Optimize-Their-Design/dp/0967762502

 

The subject vertical gear effects is one of the most important to understand driver spin, it overrules ALL other parameters, both Static, Dynamic and Spin loft who becomes useless real life due to varieties in impact location. Thats why its so simple to analyze spin issues. Low launch and low spin = low impact, and high launch high spin is high dynamic loft. That means when we test 2 different shafts, we dont know where spin came from before we compare both dynamic loft and impact location. If a certain shaft delivers more both launch and have lower spin, we know that impact was on the upper 1/3 of the face where it should be, and thats why "high launch low spin shafts" DOES deliver what they say they can do, but ONLY if impact location is in the upper 1/3 of the face, That same shaft will be a spin machine if impact is made low on the face, and the ball would hardly come up in the air at all, even with max forward shaft bending since the head will twist forward and reduce launch but vertical gear effects will generate tons of spin.

So, the next time you see a player who trace a shaft for spin issues, its NOT the shaft, but his impact position, and only if the shaft he test moves impact to a better area he will see a improvement, but that can be done without a shaft change.

[getitdaily]

Awesome stuff.

Vertical CoG is still an area I don't fully understand.

How does vertical gear effect work when CoG is high and low?

If high CoG and high impact, is spin higher or lower with same CoG and low impact?

[Howard_Jones]

@getitdaily
Since this is "your tread" as the OP, i would like to add some Trackman numbers from a 10 year old driver test where Rory is the player. Ive been using it to explain that SPIN LOFT is a LAB term that can be used under robot testing, but NEVER for humans. I simply get p...off when i see PGA trainers try to wrap a players head around the idea that his spin issues is a spin loft issue, thats pure bull s...
I dont think any of us in here is at Rorys level, not even like he was 10 years ago, so the numbers should be valid to settle that once and for all....spin comes from Vertical gear effects an vary du to impact position, NOT SPIN loft when the club is in the hands of a human.
Here is the TM report itself where ive ripped the numbers from
[img]https://s3.amazonaws.com/golfwrxforums/uploads/712/0VV49QS51YAC.png[/img]
Here is the same numbers broken down to be able to see whats going on.
[img]https://s3.amazonaws.com/golfwrxforums/uploads/705/K3IDT9F2U6YA.png[/img]
So, spin issues is NOT SPIN LOFT issues, but impact location issues...Vertical Gear effects is the ruler of spin on drivers, and it overrules ALL other parameters, and would do so even in a Robot if we moved impact.

[storm319]

It simply sounds like impatience on waiting for the free 3rd party data to be published and/or an unwillingness to pay a premium for that level of service from a custom fitter. IMHO if you aren't willing to pay the premium then it can't be that important...

[Howard_Jones]

Lets take is SLOW....

Maximized PTR (power transfer ratio or Smash factor if you like), is made if we can make impact and have COG DIRECTLY behind the ball. That avoid or eliminate head twisting, so no energy is lost in the transfer. The moment we make impact outside COG, be it vertical or horizontal, the head will twist and PTR drop.

A head with a LOW VCOG numbers is beneficial to get high launch and low spin, since the "useful face area" on the upper part of the face is larger than it is on a head with a high VCOG, and the difference to COG on the head vs ball is also what makes the head to twist, and by that change both launch angle and spin levels.

If we go deeper down in this, and follow HORIZONTAL COG, it moves depending on Face to Path like this: Its the direction COG travels at impact that matters, and face angle or face to path makes it to move heel or toe side.

That means if we want to maximize power transfeer and play a draw, we should do it with a FADE BIAS head since Horizontal COG is already a tad toe side, and moves even further out when we close face vs path.

This head is pointing strait, but look at the yellow triangle, if COG was dead center, this head would twist like crazy and cause a hook, but if COG was already toe side like it is on a FADE BIAS head, and we close face vs path like we do for a draw, COG ends up directly behind the ball and no horizontal gear effects comes to play.

 

[Howard_Jones]

Its seems like it, but if you are good friends with the folks in your local golf shop, anyone can measure and find VCOG and RCOG on the heads you look at. Im aware of the annual report form another Golf-web page, and the tolerance the instrument they use is 0.5 mm, so most of us can do it almost just as good with tools that cost a few bucks....

We need a Vise and a standard pen of the type with a button on the back we push to get the tip out and some paint.

We place the pen, in the vise tip up, and as vertical as we cant, after we have dipped the pen tip in paint and let the pen tip back into the pen.

Now we place the head face down on the pen tip, and move it until we find the spot where the head can rest on the pen tip without our support.

Hold the head in that position and push the button of the pen, and you will have a mark on the face for where VCOG is within plus minus 1 mm.

Bad photo, but it shows how simple this really is.

[getitdaily]

Ok...so, high CoG and high impact means less gearing so spin and launch are not hugely impacted by CoG?

High CoG and low impact would mean spin generally will increase? Because high CoG means more of the face gears spin up?

[Howard_Jones]

YES, you got it right, High COG and high impact = less twisting and less gear effects, so VCOG vs Impact location is VERY IMPORTANT, but so is RCOG and MOI.

A short RCOG = lower moi and more twisting, a long RCOG = higher MOI and less twisting or should we say, More stable spin and launch for the last type, and more variable for the first type.

 

TM SLDR had a very low VCOG compared to other heads, and RCOG was short, so a impact on the upper half made VERY low spin values, but low impact made VERY high spin values. Most heads on the marked has VCOG higher than the SLDR and a RCOG thats WAY longer (higher MOI, less twisting). If you made impact top the heel or toe side....only luck could bring that ball into the fairway since the horizontal gear effects becomes silly strong.

 

[rgk5]

It will never happen for three reasons.

No company wants an actual, unbiased set of COG or MOI specs published. Most consider that classified.80% of the public buys on a few shot trial, because their buddy has one, I like the look ad nauseam.Many are impulse buyers when something is new. Witness the alleged number of pre-orders on this board.

[getitdaily]

Perfect! For some reason it was hard for me to relate CoG and vertical spin rate on the vertical axis to be the same as CoG and horizontal spin rate on the horizontal axis.

I think I got it now.

And now I agree wholeheartedly that vertical CoG needs to be released by OEMs upon driver launch...lol

[Howard_Jones]

its actually simple stuff, VCOG vs impact is what we look at during testing to understand spin, and if we have 2 different heads, and we make impact the same place on both, the one with highest launch and lowest spin would be the head with shortest RCOG and lowest MOI. (like SLDR).

[Howard_Jones]

Let me add something ive forgot, RCOG and its influence for added Dynamic loft / forward shaft bending.

A LONG RCOG value means COG is longer back from the shaft center on this head vs a head with a short RCOG.

COG will FORCE its way forward to be aligned in a strait line down from your hands, and this goes for both "early and late release".

Thats why TM had a "loft up campaign" on the SLDR model, the short RCOG value did not add much Dynamic loft, so to compensate for that, we needed higher static loft.

(extreme example to show it better)

[getitdaily]

Is it correct to imply that one can use a stiffer shaft (or maybe just stiffer tip section shaft?) the farther back CoG is to help reduce that forward shaft bend?

This is also why rear CoG tends to increase closure rate, right? So to help slow closure rate by shaft alone, one would play a stiffer shaft?

[Howard_Jones]

Yes and Yes, but we cant prevent the head from coming forward, so if COG is located lets say 40 mm behind the shaft center at address, it will no matter what be forced to end 40 mm forward at impact.

High vs low launch want matter here, that only comes to play as added ABOVE that, and only for players with some load and a late release.

If you have a head with true loft, and use a launch monitor, you will be able to see how much the shaft itself contributed with.

Dynamic loft = Static loft + Angle of attack, + forward shaft bending.

So if Dynamic loft was lets say 16*, and you play a 10.5 head, and has a positive AOA of 3, we know that 13.5 was head and AOA, and 2.5 came from forward shaft bending