Why are we still using Swingweight?

[THE GOLF GUY]

2 hours ago, David LD said:

I don't have a build sheet - I can get you certain specs of you want.

 

I borrowed a swing weight scale when I built my drivers, I have different ones a different weights for different setups - I'd argue that it's quite difficult to keep the ball under the wind with a really light head. Most of my heads are closer to 200grams and I have a few which are around 230...mostly playing 75 gram shafts with a 62 gram grip

I'm also playing a lot heavier and stiffer shaft that most guys - I've seen 45 gram driver shaft setups for ppl chasing speed, but to me I feel like I'm going to split the shaft in half. I'm already swinging over 150mph club speed and I added weight for stability and control.

Now for my irons idk my current swing weight because the last 3 sets I had I bent the shafts in 30 swings or so and I had to get a custom set of the true temper x7s they made for Jason day who was also bending his shafts -they are about double the thickness of the x100 and reinforced at the tip.

Since I didn't know if they would bend on me or not I figured I'd dial them in and then weight them after - granted I'm also playing with the shaft lengths - I build all my own clubs, but it's not like I can go get fit somewhere  because not only is there no demo equipment, but I can't really even compare to a stock shaft, plus I might bend or break the stock demo stuff.

For your R7, I'd bet the head on it is at least flattened - my father had one which he played from 2006 to maybe 2015ish and the head died, if I remember correctly it actually cracked on him - and he's not a long driver, he can hit the ball,but has major back issues - it was a great driver head though.

I mean if you really want to play that head or just play around, over the past 4 years or so the biggest golf improvements have been with the shafts.

If you're looking for any specific specs or build suggestions I can give my opinion or try to point you in the right direction.

As for driver swing weight - I do just build to feel, but I'm also going off always using a 75 gram shaft 60-63 gram grip - so the only factor is head weight and then matching that to shaft cpms (stiffness) but if you hand me say a d10 and then a lighter or heavier club I could tell you this one is the d8...I was also hitting close to 40k balls at the range and breaking at least 12 drivers a vear (the heads all crack or warp only the guys using the super light shafts break shafts, I haven't broken a shaft in 8 years)

Like I was saying in my original response - the swing weight matters the most across your irons.

Most definitely the irons

[SWINGWEIGHT]

Swingweight  is a nonsense. It is there just because it makes it easier for manufacturiers to assemble their sets :

Take the heads  for an irons set with a 7grams difference between each of them as all OEMs do, cut the shafts, all the same weight  with 1/2 inch difference between each of them , take the   grips, all the same weight, take the ferrules, all the same weight, glue all af those componentst togethet put  the grps on, and her you are, the miracle happens : all of your clubs are the salme swingweight ! 
And this means that,  if you do so , when at address  or at the top of the backswing, you balance those clubs, you have the same feel as they are all of the same static  balalance. However is the club static during the swing ? Certainly not. And does it help for more co,sistency ? How could it ? However maybe that this same feel at addres makes the golfer be more confident. OK, and then he has to struggle with a  set with which, during the swing, the feel with each club will be different. Isn’t that great ?

Now think about this :  your driver  iron is swingweight D2 , 45’’  long , and weights 300 grams. Well, I can make onee, 3 meters long, weighting  3 kilos, and, thanks to much weight at but, make it D2.  Will you be able to swing is as easily and consistently as yours, which is also D2 ?

So, if you want to improve your consistencey, forget about swingweight and go to constant MOI, which is  constant dynamic balance during the swing. And , if you miss the same feel at  address, ask for your set to be constant swingweight  AND MOI !!!

[release]

23 hours ago, Marty2shanks said:

My experience - both swingweight and total weight matters.  For driver and woods I am D5-6 and play 78g in driver, 87g in 3/5w, 96g in hybrid.  Irons are D3-4 with 130g shafts.  Wedges are D4-5 with 130g shafts.  Anything lighter than that forces me to try to time the shaft and I lose feel of the face.  Anything around D0 feels awful and I have no consistency.

How much weight did you need to add to the driver head to achieve D5-6?  and the length of the driver ?

[release]

13 minutes ago, SWINGWEIGHT said:

Swingweight  is a nonsense. It is there just because it makes it easier for manufacturiers to assemble their sets :

  

Swing weight is the essential base to measure an illusive element in golf swing.  

The "feel".  Which can not be standardized and could not be taught in a lesson.

IMHO, the total weight of the golf club comes before the feel for it.  The "feel" involves many other additional elements besides the balancing pint.  

[SWINGWEIGHT]

2 minutes ago, release said:

Swing weight is the essential base to measure an illusive element in golf swing.  

The "feel".  Which can not be standardized and could not be taught in a lesson.

IMHO, the total weight of the golf club comes before the feel for it.  The "feel" involves many other additional elements besides the balancing pint.  

Read me again please I did'nt said that the feel should be standardized . Nor did I talked  about lessons. I said that when a set is assembled to constant swingweight, and I will add, with  same shafts for each club of  the set, the feel, at address,  will be the same  and a vast majority of golfers like that. However  it definitely cannot help to get a consistent swing  with each club of the set.
Then, I don't undertsand what you mean when saying "Swing weight is the essential base to measure an illusive element in golf swing"

[SWINGWEIGHT]

16 minutes ago, release said:

Swing weight is the essential base to measure an illusive element in golf swing.  

The "feel".  Which can not be standardized and could not be taught in a lesson.

IMHO, the total weight of the golf club comes before the feel for it.  The "feel" involves many other additional elements besides the balancing pint.  

Indeed, total weight matters a lot , however  this  doesn't mean that it comes before the feel, which also matters a lot as, when the golfer is pleased with the feel he gets , in the swing with each of his clubs , it definitely helps him to being more consistent whatever club he hits.
So, we should look for the best feel , as well as  best weight and best dynamic balance, i.e. MOI for each club of a set. And having such assembled sets helps a lot.

[cnosil]

1 hour ago, SWINGWEIGHT said:

Swingweight  is a nonsense. It is there just because it makes it easier for manufacturiers to assemble their sets :

Take the heads  for an irons set with a 7grams difference between each of them as all OEMs do, cut the shafts, all the same weight  with 1/2 inch difference between each of them , take the   grips, all the same weight, take the ferrules, all the same weight, glue all af those componentst togethet put  the grps on, and her you are, the miracle happens : all of your clubs are the salme swingweight 

I am not saying swingweight matters but your explanation is an oversimplification.   The target weights for each of the components is the same but they don’t actually all come out the same.  Manufacturing tolerances allow for a few grams in each direction thus a few SW points in either direction.  

 

 

 

[SWINGWEIGHT]

8 minutes ago, cnosil said:

I am not saying swingweight matters but your explanation is an oversimplification.   The target weights for each of the components is the same but they don’t actually all come out the same.  Manufacturing tolerances allow for a few grams in each direction thus a few SW points in either direction.  

 

8 minutes ago, cnosil said:

This is definitely not so , except for the grips and ferrules, there is no target weight identical  for each of the components, as you say, with, however the exception of  single length irons sets.  But    your knowledge about golf clubs seems very limited. As for the manufacturing tolerances, this is not the issue we are discussing.
Thank you !

 

 

 

[KCEE]

18 hours ago, U-Gruv said:

From what I understand, with grips being identical weight. shaft weights consistent, and head weights equally gapped at +7gms, with non-constant weight shafts (typically parallel tip), assembly with progressive swing weights as the target, from 4 iron (D0) to the GW (D3) by adding tip weights or slightly adjusting the length gaps, will provide you a fairly closely matched set from an MOI perspective.  If the shafts are constant weight (typically but not always the taper tip shafts), then using fixed length gaps and no weight manipulation in the heads will yield progressive swing weights and therefore closely matched MOI measurements.  Thoughts?  

If you have the "standard" 1/2" length progression in a set of irons then you would want 8 grams progression in the heads to MOI match assuming you are using the same shafts and grips.  If the heads are 7 grams apart then a 3/8" length gap progression would achieve the MOI match. I remember this from Bill Totten and then Dave Tutelman's articles about Swing weight vs MOI. Tutelman still has his website up with some good info on all of this.

I don't have a MOI pendulum to measure, but I use an Excel spreadsheet where I can plug in the weights of all components and even the balance point of each shaft to calculate the MOI of the finished club. That said going 8 grams each head is probably close enough for most of us. 

In my case I still struggle with the longer irons even when they are MOI matched. I find they are too light overall so adding a backweight gets the static weight up while leaving the MOI alone. My 6 iron usually has at least a 15 gram back weight. My woods usually have 20-25 grams backweight even though I don't use "light" shafts.

[Marty2shanks]

1 hour ago, release said:

How much weight did you need to add to the driver head to achieve D5-6?  and the length of the driver ?

12 grams more than the stock weight inserts.  45” length.  Head is a TM R11S.  Aldila RIP Phenom X-Stiff flex shaft.  108mph swing speed.  260 carry.  285 total. I have newer drivers (TM M5, TM R1, Callaway Mavrik, Titleist 917, Mizuno ST200) but nothing matches this combo for length and accuracy.  Mavrik is longer, but not as consistent.  Everything else is about same distance (or slightly less) but not as accurate. I am sure with the added weight I am at the MOI limits, but havr no way of testing that.

[cnosil]

48 minutes ago, SWINGWEIGHT said:

 

This is definitely not so , except for the grips and ferrules, there is no target weight identical  for each of the components, as you say, with, however the exception of  single length irons sets.  But    your knowledge about golf clubs seems very limited. As for the manufacturing tolerances, this is not the issue we are discussing.
Thank you !

 Your original statement said take each of the components and put them together and you get the same swingweight.  This typically is not true due to component tolerances:

• coubhead  typically +/- 2-4 grams
• grips typically +/- 3 grams
• shaft typically +/- 4-5 grams
• Balance point typically +/- 1/8” 

How does this according to your statement “It is there just because it makes it easier for manufacturers to assemble their sets”?   make it easier to get to advertised/desired swingweights?    we know that most OEMs just assemble clubs by grabbing a component out if a box which potentially results in swing weights all over the map.  
 

While not directly the topic  being discussed, you should still attempt to be accurate with the information you are presenting and  since you believe my knowledge “seems very limited” attempt to educate those on the forum and not dismiss things as not being relevant.  
 

Swingweight is simply just another basically meaningless number used in the golf industry that is only relevant to the individual club being assembled but needs to be combined with additional information to make meaningful to a set of clubs and the player.  

[BigBoiGolf]

I'm inclined to agree with @Dave Tutelman on this, and from my experience both building and doing advanced play, I'll point out why:

1. It doesn't make sense that adding weight in general should make an object feel "lighter" even though the scale tells me it's balanced to be lighter. I don't hold the club at the swingweight's 14" fulcrum point, so any balance measurement with respect to this point is, to me, pointless. While the MOI meter measures directly at the end cap, I would assume in good faith that simply gripping down 1/2" to 1" from this end cap would theoretically decrease how much work I must perform on the club to displace it through 3D space. Compared to a swingweight machine, the MOI meter gives me the absolute worst case scenario for first-moment work, where swingweight because I can't grip or swing at 14", gives me a scenario I cannot possibly ever do.

2. Even with lighter swingweights, there's no mechanical advantage I am seeing to be made with a particular installed golf shaft. If we are to take other professional's work, like Russ Ryden who does in my opinion probably the best shaft profiling and measuring, and more important normalization of golf shafts in the industry, we would see that simply adding extra weight to the handle or a reduction in tip weight (that one could accomplish by bore drilling or weight kit removal) shouldn't result in some dramatic effect of how the shaft would load and release, and if we were to do significant tip weight reduction, we're probably looking at selecting a different shaft entirely, because from the physical viewpoint of the shaft, it is merely responding to tip weight. This makes the most sense because as I've seen professional builds, shaft tip trimming is becoming more popular, but I also see a higher baseline weight of drivers that is encroaching on Fairway Wood category. I had found a MacGregor Tourney Steel 5 wood head in my basement and it weighed 210 grams, and this was probably manufactured in the 1980s

3. I had an old golf club, an Epic Flash with a UST Proforce V2 7F5, that I built with a Winn DriTac Lite standard grip, where I removed all the weight in the head, including the track mount weight, and assembled at 46", and was able to perform my fastest swing at 133mph. So I went down to the R7 SuperQuad, pulled all the weight out, and did 2 build sheets with more precise measurements, and I will be completely honest, the weightless build felt completely fine and pretty similar to that Epic Flash experimental build. My mom has an old iron from 2001 and I've taken it to the range to hit a few "sizzler" shots and it was just remarkable at how light it was, yet it performed shot after shot and after 50 - 60 shots, I didn't feel worse for wear, her club's MOI was 2660 kg-cm^2

I think it's just one of those things that has stuck around because we didn't have different grip weights, we always had these steel shafts where the balance point uncut was 50%, and it feels like we're desperately clinging onto these designations that feel more... mystical than practical. From my perspective I'm using muscular power that is draining me with every swing, requiring a fresh shot of carbs to maintain performance (it's more of an excuse to drink while playing but I'm not complaining!), so I'm more inclined to make the work easier for me to do while maintaining a similar performance.

After all, isn't that the point of fitting? The same or less work with the same or better results?

Edited May 9 by BigBoiGolf

[N.O.Hustle54]

I've tried my tinkering with swing weights. For years I would weight and use tip weights and then lead tape. About two years ago I removed the tape and I no longer add weight. My handicap has gotten consistently better since I stop being concerned about swing weight. I have gotten fitted and changed shafts to heavier KBS 130 X-stiff and have shown consistent improvement. Now it is simply about feel. If the club head / shaft combo feels right, give yourself 5-6 rounds to hone it all in or a few weeks of consistent practice and watch how better your contact will become.

[Dave Tutelman]

1 hour ago, BigBoiGolf said:

I'm inclined to agree with @Dave Tutelman on this, and from my experience both building and doing advanced play, I'll point out why: .....

We're very much in agreement here, BigBoiGolf. Even to our opinion of what Russ Ryden is doing. Just a few things I'd like to point out.

A lot of the discussion -- too much in my opinion -- is centering around the fact that 14" is not a pivot or fulcrum for anything real. While true, that completely misses the point. The inventor of swingweight, I am almost sure, picked 14" empirically, because it simulated moment of inertia across a wide variety of clubs. That, and not any physical reasoning, is behind the number 14".

If you look at the graphs I mentioned in my previous comment, you will notice that swingweight and moment of inertia track very well against one another, if all you vary is head weight or overall shaft weight or club length. If you consider swingweight to be a "cheap and dirty" way to measure moment of inertia, the errors are less than 10% for each of those club properties. (That relationship falls apart completely when you look at grip weight. We'll get back to that in point #3 below.) Until the 2000s, it was quite expensive to actually measure MOI, which cannot be done statically. (Well, either expensive or tedious and math-intensive.) So a swingweight scale was a remarkably good shop tool for getting an approximate MOI match. Very few of the clubfitters who used the tool every day knew that, but physics and history strongly suggest it is true.

With 20:20 hindsight, here are a few things we need to think about when we think about swingweight:

1. I have shown elsewhere that a really good MOI match can be obtained by doing a swingweight match with a sloped swingweight of a little over one point per inch of club length. This gets much closer to a true MOI match than a straight swingweight match does.
2. All of this -- the origin of the swingweight scale, the sloped swingweight match, etc -- depends on varying length and clubhead weight only. There is a second correction for changes in shaft weight. Anything else simply does not fit the model, and can give nonsense results if you do them to match swingweight. That includes different weight grips, counterweighting, lead tape in the middle of the shaft, etc. The talk about a D-0 telephone pole is no more than a joke based on this truth.
3. If you think about when swingweight was invented (the 1940s), there was not much choice in shaft weight and even less in grip weight. So swingweight worked fairly well as an MOI surrogate for the clubs you could build back then. With today's ability to play with shaft weight profiles and grip weights, swingweight is no longer a reliable surrogate for MOI -- unless you are careful not to use those "knobs" to adjust your clubs.

[HikingMike]

Great discussion.

From a physics perspective, doesn't this mostly boil down to two things - overall weight, and center of gravity (COG distance from hands and/or shoulders)? The center of gravity is the thing you are swinging. With planets and stars or whatever, you can calculate everything you need to using the centers of gravity. 

Now shaft flex muddies the water a little, more flex, more muddy. Same with planets - gravity can "stretch" or "bulge" a planet a bit, cause flexing, or like the ocean's tides due to the Moon, bulge around the equator due to rotation and centripetal force.

But if we assume no flex for ease of thinking, then you have weight and center of gravity location. If the center of gravity is further from the hands/shoulders, then it will swing heavier (assuming same overall weight). If the overall weight is heavier, then it will swing heavier (assuming same center of gravity distance). 

At the top of your backswing, you are stopping a swing, and starting a swing - stopping the club and starting the club. That's acceleration. Force = mass * acceleration. That's what you feel, the force.

Obviously there are a lot of messy things going on with the swing and it's not just a simple weight on a stick physics problem. But if you want to abstract it, that's a big part of it.

[BigBoiGolf]

2 hours ago, HikingMike said:

Great discussion.

From a physics perspective, doesn't this mostly boil down to two things - overall weight, and center of gravity (COG distance from hands and/or shoulders)? The center of gravity is the thing you are swinging. With planets and stars or whatever, you can calculate everything you need to using the centers of gravity.

It's more tip weight and length of that weight from the "center of input". Realistically it's our hands, An MOI meter uses the end cap of the grip because it's just easier to measure it that way.

In Example a the estimated MOI is Because the target axis Omega sits equally between 2 masses m at distance R

The golf club is more like Example b, where the estimated MOI is closer to Because the target axis Omega is closer to the hands

These are not the correct formulas to represent a golf club or swing, as the swing can be more simplified as a multi-pendulum movement, but you can see shifting the target axis of input can result in massive discrepancies in force required to move or rotate an object

Source: https://phys.libretexts.org/Bookshelves/University_Physics/University_Physics_(OpenStax)/Book%3A_University_Physics_I_-_Mechanics_Sound_Oscillations_and_Waves_(OpenStax)/10%3A_Fixed-Axis_Rotation__Introduction/10.06%3A_Calculating_Moments_of_Inertia

 

2 hours ago, HikingMike said:

Now shaft flex muddies the water a little, more flex, more muddy. Same with planets - gravity can "stretch" or "bulge" a planet a bit, cause flexing, or like the ocean's tides due to the Moon, bulge around the equator due to rotation and centripetal force.

Shaft flex, or realistically more so shaft weight (because there's a positive relationship between shaft weight and EI Area Under the Curve) is more so about the transition force, tempo and slotting where the player can place the golf club in such a way to move it efficiently as if it were orbiting it.

Consider the following diagram of orbiting bodies:

From the top of the golf swing we actually start the hands down a path similar to Instantaneous Velocity 1, while the head is still moving back behind us, putting a massive strain on the golf shaft in order to change directions without suffering from plastic deformation. The hands, for a short time, will essentially be pulling the golf club at basically the tangent of the current position, which when factoring in centripetal acceleration, result in a path similar to 3.

Not all things last, generally around the trail leg as you are unable to keep pulling the hands around you in a tangent direction, the form breaks down and the release essentially begins, and the stored energy of the golf shaft creates kind of a "kicking" motion to fling the clubhead forward (usually in combination with pushing very hard into the ground with the lead foot to pivot the hip upwards and "fling" the club to boost velocity)

If you cannot load the shaft you'll likely hear a concern that the shaft is "lifeless" or boardy. If you over-load the shaft, you'll hear a concern about it being too wobbly or unpredictable during the release.

In truth, you need to go back and forth between shaft weight/flex, and the calculated moment of inertia for the entire club, to have a club that doesn't require significant effort to move around or pre-load, and doesn't require exceptional force to maintain its tangent path while also hitting the sweet spot of being able to load, but not over-load the golf shaft to get it ready for release.

If I had to do a fitting all over again, I'd start at shaft weight and work my way down in 10 gram increments, and I wouldn't care too much about flex since it's not standardized anyways. Once I find a decent spot, I'd work through different makeups to find and estimate the MOI of the club, then work around that reference point however you like.

You don't have to make your entire bag the same MOI if you want, I usually separate them into groups based on what shaft I'm using.

In summary: We care about MOI because of what we're doing at our hands. We care about shaft weight and tip weight and flex because of what we're doing at the tip of the golf shaft. One is input, the other is taking that input and transforming it.

Edited May 9 by BigBoiGolf

[Dave Tutelman]

On 5/8/2024 at 8:11 AM, release said:

I had read that the irons in Ben Hogan's bag had different swing weights in the set.  Lower swing weight numbers in the long irons and higher swing weight numbers in the short sticks.  It is what the man felt "right" for his preference to produce the trajectory flight shapes he wanted.

It is certainly worth noting that this progression of swingweight is a step in the direction of MOI matching. In fact, if the swingweight changed by about 2/3 of a point from each club to the next, it was a very good MOI match.

Bobby Jones's career predates swingweight. But I have read that his clubs were matched by the head weights times the square of the length. This is also closely related to an MOI match.

[bigtmatdaddy]

I think it represents the quality of the build and the consistency of each club. I’ve checked so many brand new custom irons that were all over the map. Just do your job and make the set with accuracy. 

[Dave Tutelman]

11 hours ago, bigtmatdaddy said:

I think it represents the quality of the build and the consistency of each club. I’ve checked so many brand new custom irons that were all over the map. Just do your job and make the set with accuracy. 

That's a "yes but". People with a swingweight scale who don't understand it thoroughly might conclude "swingweights all over the map" when in fact the build accurately accomplished exactly what was needed. A properly MOI-matched set will not all be the same swingweight. Unless you graph the swingweights and notice they are carefully sloped (but not identical), you might conclude this is a sloppy set.

[Dave Tutelman]

18 hours ago, HikingMike said:

From a physics perspective, doesn't this mostly boil down to two things - overall weight, and center of gravity (COG distance from hands and/or shoulders)? The center of gravity is the thing you are swinging... 

Now shaft flex muddies the water a little, more flex, more muddy... But if we assume no flex for ease of thinking, then you have weight and center of gravity location. If the center of gravity is further from the hands/shoulders, then it will swing heavier (assuming same overall weight). If the overall weight is heavier, then it will swing heavier (assuming same center of gravity distance). 

At the top of your backswing, you are stopping a swing, and starting a swing - stopping the club and starting the club. That's acceleration. Force = mass * acceleration. That's what you feel, the force.

...

Obviously there are a lot of messy things going on with the swing and it's not just a simple weight on a stick physics problem. But if you want to abstract it, that's a big part of it.

That is part of it, perhaps even a big part. But weight (really mass) and force are useful for static feel and motion in a straight line. As the club picks up speed, more of the motion is rotational. At impact, 80% of the clubhead speed is due to angular velocity and only 20% to linear. (Could be more biased than that; I've seen studies go down to 87-13, but none more equal than 80-20 for decent golf swings.)

So we need to account for angular motion as well. That means torque and moment of inertia, which are the angular equivalents of force and mass.

Weight and CG reflect the zeroth and first moments of the club's mass. In order to reflect rotational acceleration/motion, you also need the second moment of the mass -- the moment of inertia.

How does this fit golf reality? In fittings I have seen where each club was separately fit until they all felt the same, the set was very close to a moment of inertia match and not very close to a swingweight match. That means it probably isn't all about the transition nor static feel, but rather about feel as the club approaches impact -- rotating more than translating.

[BigBoiGolf]

I'll drop off this interesting bit of info since I always try to see how pros are setting up their gear for reference points, the below picture is of the Nike Ignite 340SF Tiger Woods was using with an 83 gram Diamana shaft around 2004, note the headweight is ~201 grams, and he was playing his driver at 43.5 inches assembled. I'll post later my MOI results from a counter balanced shaft installed in my driver at 45", and a non-cb shaft installed at 45", same headweight. That will also give us a rough idea how much MOI is being affected by the "same weight, same length, different balance point" concept.

 

[HikingMike]

17 minutes ago, BigBoiGolf said:

I'll drop off this interesting bit of info since I always try to see how pros are setting up their gear for reference points, the below picture is of the Nike Ignite 340SF Tiger Woods was using with an 83 gram Diamana shaft around 2004, note the headweight is ~201 grams, and he was playing his driver at 43.5 inches assembled. I'll post later my MOI results from a counter balanced shaft installed in my driver at 45", and a non-cb shaft installed at 45", same headweight. That will also give us a rough idea how much MOI is being affected by the "same weight, same length, different balance point" concept.

 

I feel like we need a little more explanation on this photo! That is something. That's a Nike sticker on there. Is this the same actual head Tiger used, or just the same setup? Definitely interesting stuff about his driver setup. Compared to today, this is a light driver head, short shaft, heavy shaft.

Your MOI comparison sounds excellent.

Btw, great physics post above too.

[Dave Tutelman]

22 minutes ago, BigBoiGolf said:

I'll drop off this interesting bit of info since I always try to see how pros are setting up their gear for reference points, the below picture is of the Nike Ignite 340SF Tiger Woods was using with an 83 gram Diamana shaft around 2004, note the headweight is ~201 grams, and he was playing his driver at 43.5 inches assembled. I'll post later my MOI results from a counter balanced shaft installed in my driver at 45", and a non-cb shaft installed at 45", same headweight. That will also give us a rough idea how much MOI is being affected by the "same weight, same length, different balance point" concept.

Let me predict what will happen. IIRC, you have an GolfMechanix MOI meter.

I gather from what you say, you intend to compare two drivers with the same head weight (I hope approximately the same head design), the same length, the same shaft model, the same grip, but one will will have extra weight in the butt of the shaft. (That's what I interpret "counterweight" to mean.)

They will have very similar MOI measurements. The counterweighted one will be slightly higher, but the difference will be very small. But the counterweighted driver will have a noticeably lower swingweight, by about 3 points for each 10 grams of counterweight.

Please let us know how that works out.

[BigBoiGolf]

4 hours ago, Dave Tutelman said:

Let me predict what will happen. IIRC, you have an GolfMechanix MOI meter.

I gather from what you say, you intend to compare two drivers with the same head weight (I hope approximately the same head design), the same length, the same shaft model, the same grip, but one will will have extra weight in the butt of the shaft. (That's what I interpret "counterweight" to mean.)

They will have very similar MOI measurements. The counterweighted one will be slightly higher, but the difference will be very small. But the counterweighted driver will have a noticeably lower swingweight, by about 3 points for each 10 grams of counterweight.

Please let us know how that works out.

TEST SCOPE:

To investigate the difference between Counter Balanced Golf Shafts and Non-Counter Balanced Golf Shafts of similar total weight class of their effects on Swingweight and Moment of Inertia

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TEST CANIDATES:

2 Driver Heads from GolfWorks, the Maltby KE4 Tour TC and Maltby KE4 TC Pro, were selected alongside 2 assembled golf shafts with the same Maltby Driver Adapter. The golf shafts are the UST-Mamiya ProForce V2 2022 7F5, and the True Temper Project X HZRDUS Yellow 2018 76 6.5, both assembled with Lamkin UTX Cord Blue grips.

The UST ProForce V2 had a prior assembled length when installed to the KE4 Tour TC of 45.75", and was selected for a second measurement series to document butt trimming's effects on both Swingweight and Moment of Inertia. The ProForce V2 was then trimmed 7/8" to match the installed length of the Project X HZRDUS Yellow shaft in both canidate heads.

 

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CANIDATE SPECS:

Maltby KE4 Tour TC

• Lie: ~59
• Head Weight without Adapter: 191.71g
• Loft: ~10
• Volume: ~460cc

Maltby KE4 TC Pro

• Lie: ~57
• Head Weight without Adapter: 191.68g
• Loft: ~9
• Volume: ~440cc

UST Proforce V2 7F5 Sample A:

• Installed Length (KE4 TC Pro): 45.825"
• Installed Length (KE4 Tour TC): 45.75"
• Unassembled Weight (with adapter and grip): 132.34g

UST Proforce V2 7F5 Sample B:

• Installed Length (KE4 TC Pro): 45"
• Installed Length (KE4 Tour TC): 44.825"
• Unassembled Weight (with adapter and grip): 130.61g

Project X HZRDUS Yellow 76 6.5:

• Installed Length (KE4 TC Pro): 45"
• Installed Length (KE4 Tour TC): 44.825"
• Unassembled Weight (with adapter and grip): 129.35g

-------------------------------------------------------------------------------------------------------------------------------------

TEST RESULTS:

UST ProForce V2 7F5 Sample A -> KE4 Tour TC:

• Swingweight: D3.2
• MOI
  • 3023.6
  • 3024.1
  • 3024.2

UST ProForce V2 7F5 Sample A -> KE4 TC Pro:

• Swingweight: D4.7
• MOI
  • 3046.7
  • 3045.8
  • 3046.4

UST ProForce V2 7F5 Sample B -> KE4 Tour TC:

• Swingweight: C9.5
• MOI
  • 2898.7
  • 2897.5
  • 2897.0

UST ProForce V2 7F5 Sample B -> KE4 TC Pro:

• Swingweight: D0.2
• MOI
  • 2920.8
  • 2918.9
  • 2918.5

Project X HZRDUS Yellow 76 6.5 -> KE4 Tour TC:

• Swingweight: C6.5
• MOI
  • 2868.5
  • 2866.1
  • 2866.7

Project X HZRDUS Yellow 76 6.5 -> KE4 TC Pro:

• Swingweight: C7.2
• MOI
  • 2888.0
  • 2887.5
  • 2888.2

Edited May 10 by BigBoiGolf
Re-Organized Data

[Dave Tutelman]

2 hours ago, BigBoiGolf said:

TEST SCOPE:

To investigate the difference between Counter Balanced Golf Shafts and Non-Counter Balanced Golf Shafts of similar total weight class of their effects on Swingweight and Moment of Inertia

TEST CANIDATES:

2 Driver Heads from GolfWorks, the Maltby KE4 Tour TC and Maltby KE4 TC Pro, were selected alongside 2 assembled golf shafts with the same Maltby Driver Adapter. The golf shafts are the UST-Mamiya ProForce V2 2022 7F5, and the True Temper Project X HZRDUS Yellow 2018 76 6.5, both assembled with Lamkin UTX Cord Blue grips.

The UST ProForce V2 had a prior assembled length when installed to the KE4 Tour TC of 45.75", and was selected for a second measurement series to document butt trimming's effects on both Swingweight and Moment of Inertia. The ProForce V2 was then trimmed 7/8" to match the installed length of the Project X HZRDUS Yellow shaft in both canidate heads.

 [ deleted Russ Ryden's EI specs ]

CANIDATE SPECS:

Maltby KE4 Tour TC

• Lie: ~59
• Head Weight without Adapter: 191.71g
• Loft: ~10
• Volume: ~460cc

Maltby KE4 TC Pro

• Lie: ~57
• Head Weight without Adapter: 191.68g
• Loft: ~9
• Volume: ~440cc

UST Proforce V2 7F5 Sample A:

• Installed Length (KE4 TC Pro): 45.825"
• Installed Length (KE4 Tour TC): 45.75"
• Unassembled Weight (with adapter and grip): 132.34g

UST Proforce V2 7F5 Sample B:

• Installed Length (KE4 TC Pro): 45"
• Installed Length (KE4 Tour TC): 44.825"
• Unassembled Weight (with adapter and grip): 130.61g

Project X HZRDUS Yellow 76 6.5:

• Installed Length (KE4 TC Pro): 45"
• Installed Length (KE4 Tour TC): 44.825"
• Unassembled Weight (with adapter and grip): 129.35g

TEST RESULTS:

UST ProForce V2 7F5 Sample A -> KE4 Tour TC:

• Swingweight: D3.2
• MOI
  • 3023.6
  • 3024.1
  • 3024.2

UST ProForce V2 7F5 Sample A -> KE4 TC Pro:

• Swingweight: D4.7
• MOI
  • 3046.7
  • 3045.8
  • 3046.4

UST ProForce V2 7F5 Sample B -> KE4 Tour TC:

• Swingweight: C9.5
• MOI
  • 2898.7
  • 2897.5
  • 2897.0

UST ProForce V2 7F5 Sample B -> KE4 TC Pro:

• Swingweight: D0.2
• MOI
  • 2920.8
  • 2918.9
  • 2918.5

Project X HZRDUS Yellow 76 6.5 -> KE4 Tour TC:

• Swingweight: C6.5
• MOI
  • 2868.5
  • 2866.1
  • 2866.7

Project X HZRDUS Yellow 76 6.5 -> KE4 TC Pro:

• Swingweight: C7.2
• MOI
  • 2888.0
  • 2887.5
  • 2888.2

BigBoiGolf, please help me out here. I'm having a lot of trouble interpreting this experiment. I tried to make a table out of your lists (thanks for the color-coding; I think that helped), but I am failing on some very important considerations. Let me ask a very few questions, and see if the answers allow me to make the table so I can view what is going on.

1. Is "installed length" the same as "club length with shaft installed"? If not, then what is installed length, and what is the club length?
2. Where is the counterweight? I see three shafts of roughly equal weight with grip and adapter. I don't see anything that suggests a counterweight.
3. Why two heads? Since you have adapters, it seems one head would answer the question just fine.
4. Why more than one installed length? That should not tell me much of anything. Two of the shafts are pretty much the same length, the other is a good 3/4" longer.

Let's see if the answers to these questions let me see what the experiment should show. Thanks. If you want to continue this discussion in private (outside the forum) and come back and report results, contact me at [email protected].

[BigBoiGolf]

7 hours ago, Dave Tutelman said:

BigBoiGolf, please help me out here. I'm having a lot of trouble interpreting this experiment. I tried to make a table out of your lists (thanks for the color-coding; I think that helped), but I am failing on some very important considerations. Let me ask a very few questions, and see if the answers allow me to make the table so I can view what is going on.

1. Is "installed length" the same as "club length with shaft installed"? If not, then what is installed length, and what is the club length?
2. Where is the counterweight? I see three shafts of roughly equal weight with grip and adapter. I don't see anything that suggests a counterweight.
3. Why two heads? Since you have adapters, it seems one head would answer the question just fine.
4. Why more than one installed length? That should not tell me much of anything. Two of the shafts are pretty much the same length, the other is a good 3/4" longer.

Let's see if the answers to these questions let me see what the experiment should show. Thanks. If you want to continue this discussion in private (outside the forum) and come back and report results, contact me at [email protected].

Hi Dave, I re-organized the Table to show you the combinations better

 

Quote

Is "installed length" the same as "club length with shaft installed"? If not, then what is installed length, and what is the club length?

I have updated the terminology to better reflect that this is the total assembled length

Quote

Where is the counterweight? I see three shafts of roughly equal weight with grip and adapter. I don't see anything that suggests a counterweight.

The Project X HZRDUS Yellow is counter-balanced approx. 2" more than the UST Proforce V2. If you would like me to take different measurements with counter weights, please let me know. I have updated the table to specify Counter-Balanced, Counter-Weight addition, and Counter-Weight location from Grip Cap.

Quote

Why two heads? Since you have adapters, it seems one head would answer the question just fine.

Extra measurements and possible Control Group, especially since the headweights without an adapter were so similar.

Quote

Why more than one installed length? That should not tell me much of anything. Two of the shafts are pretty much the same length, the other is a good 3/4" longer.

I took advantage of the opportunity to measure the UST Proforce V2 in its original state at a more popular driver length, since I was to trim it to match the HZRDUS Yellow. It has been Labeled in the Table as S1-A, S1-B to indicate pre-post end trim for your reading.

If you'd like me to test more Counter-Balance or Counter-Weights now that we have a baseline, let me know what you'd like to see and I can send you the data when I have time. Enjoy!

 

Edited May 11 by BigBoiGolf
Fixed wrong "Counter Balanced?" Table Value

[Dave Tutelman]

21 hours ago, BigBoiGolf said:

Hi Dave, I re-organized the Table to show you the combinations better

Thanks. That is a big help. But even more help is the explanation...

21 hours ago, BigBoiGolf said:

The Project X HZRDUS Yellow is counter-balanced approx. 2" more than the UST Proforce V2. If you would like me to take different measurements with counter weights, please let me know. I have updated the table to specify Counter-Balanced, Counter-Weight addition, and Counter-Weight location from Grip Cap.

I take that to mean that the HZRDUS' balance point is 2" higher than the ProForce. The rest of my response assumes you mean that.

With that information, I can do some quantitative things with with swingweight. I can perhaps draw some qualitative conclusions about moment of inertia, but can't get really quantitative.  (Remember, swingweight and balance point are static measurements. Moment of inertia is dynamic; it can't be deduced from just weight and balance point, but needs more detailed information about the weight distribution.) If this discussion leaves you wanting more, we can talk about further tests.

For purposes of discussion, let me give some intuitive names to the shafts:

• S1-A is "long". It is 5/6 of an inch longer than the other two.
• S1-B is "nominal".
• S2 is "highBP". (I prefer that to "counterbalanced", because the latter can be done in so many ways. This one is same weight but a higher BP, which I would not have though of as counterbalanced before this discussion.)

So here are my observations. The numbers relate to the H1 head, but the numbers and the observations are similar for the H2 head.

1. "Long" is 4.5 swingweight points higher than "nominal". If you asked me to guess off the top of my head, I'd have guessed 5 points, using a rule of thumb of 6 points per inch of length. If you look at more precise tables of sensitivity, you see driver a little less than 6, so the 4.5 points makes even more sense.
2. "Long" is 127kg-in^2 higher MOI than "nominal". That is a little higher than I would have guessed but really pretty close. Sensitivites say that a swingweight point is worth about 20kg-in^2 for more-or-less similar clubs, which these are. By that rule of thumb, 127kg-in^2 is a little more than 6 swingweight points. But then, MOI is proportional to the square of length, so changing the length might change the MOI faster than the swingweight. So, still a very sane result.
3. "HighBP" is 3 points lower swingweight than "nominal". Let's take a raw shaft weight of 71g (130g assembly - 51g grip - 8g adapter), and move the balance point 2 inches up the shaft. That will reduce the torque on the swingweight scale by 71g*2in=142g-in. Since a swingweight point is 50g-in, that is a drop of 2.8 swingweight points. Very close match to the 3 points that was measured.
4. "HighBP" is 32kg-in^2 lower MOI than "nominal". Again, using a rule of thumb of 20kg-in^2 equivalent to a swingweight point, that is only 1.6 points; that is considerably less than the 3 points of actual swingweight that we lost. This is the sort of number I would expect. Counterweighting doesn't do nearly as much for MOI as for swingweight. In fact, a pure counterweight -- a weight added at the butt -- should actually increase the MOI. But I can't make a quantitative calculation here. That is because I don't know the actual weight distribution of the "highBP" shaft, and I would need to know it for an MOI calculation. Just knowing how much the BP moves tells me static stuff, but nothing dynamic.

So this is a pretty good sanity check for the theory (by my calculations) and your measurements. If we want to be more precise, we would need to do an actual counterweighting of the "nominal" shaft and compare that.

I'll leave it to you whether you want to go that additional step. It will be quite a bit more work. The swingweight part is pretty easy; just tape a weight to the grip outside the shaft even with the butt. But I don't know if this can be done rigidly enough to clamp the butt in the MOI meter and expect the weight to follow exactly; you may have to stuff the weight into the shaft, which means removing the grip and re-gripping.

Whatever you feel like doing. If you do more, I will gladly analyze the results.

This has been a fun discussion. Thanks much!

DaveT

 

[Julius]

This is a part of the science that I never really knew about or studied,  I have to say it is new to me as a concept.  Can someone explain in plain English (I am not an engineer) why it is so relevant? If you are fitted for clubs (I play PING mostly) I would assume this is addressed in that process? 

 

Edited May 12 by Julius

[Dave Tutelman]

11 hours ago, Julius said:

This is a part of the science that I never really knew about or studied,  I have to say it is new to me as a concept.  Can someone explain in plain English (I am not an engineer) why it is so relevant? If you are fitted for clubs (I play PING mostly) I would assume this is addressed in that process? 

Julius, I'm an engineer, so it is a little hard for me to completely drop the technical stuff. But the first page of my web article about swingweight and MOI, while somewhat technical, avoids the math and keeps the explanation to words and pictures. You might find it a good introduction. Or maybe not.

If you get through the first page, continue on until you are in over your head. No matter how far this is, you are going to learn a bunch about the topic.

[HikingMike]

1 hour ago, Dave Tutelman said:

Julius, I'm an engineer, so it is a little hard for me to completely drop the technical stuff. But the first page of my web article about swingweight and MOI, while somewhat technical, avoids the math and keeps the explanation to words and pictures. You might find it a good introduction. Or maybe not.

If you get through the first page, continue on until you are in over your head. No matter how far this is, you are going to learn a bunch about the topic.

Nice! Great read, thanks. I finished it, though didn’t read any of the linked material.