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Post by dubiousgolfer on Sept 13, 2020 7:34:01 GMT -5
Just thought I'd add a thread to amalgamate what I've found on the internet concerning ROC . Looking at Phil Cheethams diagram Fig 8 below , CCV (=ROC) is dependent on 3 parameters: 1. Clubhead speed 2. Swing Plane Inclination (the more vertical the club shaft swing plane the less the ROC) 3. Handle Twist Velocity This is also confirmed by Sasho MacKenzie article link: golf.com/instruction/what-is-rate-of-closure-golf-swing-sasho-mackenzie/He mentions that it won't benefit a golfer to reduce his clubhead speed and that tour players " tend to have relatively similar vertical swing planes with driver (40° to 45° from vertical)". I find the above statement very confusing because I'm assuming most drivers have similar lie angles and although their shaft characteristics in terms of shaft bend and clubhead droop might differ , I cannot imagine their clubshaft swing planes being vastly different. The golfers might swing their arms/hands down different planes but surely the clubshaft plane at impact must be virtually the same? Therefore I don't understand how one can change their 'vertical planes' unless they change the lie angles of their drivers. Sasho Mackenzie also mentions on his twitter account the following: "Variability in ROC was moderately correlated to dispersion. Lower dispersion players are able to repeat their ROC at impact regardless of its magnitude."He mentions the following on his article link above: " I’ve measured Jon Sinclair (former professional) hit a smooth 86 mph 6 iron with a high RoC of 25 °/ft, and immediately follow it up with an 88 mph 6 iron with a low RoC of 13 °/ft. Both shots carried over 180 yards with relatively straight trajectories."Doesn't this seem to suggest that golfers with good hand/eye coordination (ie. skill) is a relevant factor rather than magnitude of ROC? Some more SMK comments: Here’s some other ‘lack of evidence’ presented by Ping the last time the World Scientific Congress of Golf was in St. Andrews. No relationship between ROC and either handicap or dispersion. SMK comments relating to Alex Saary graph below using "Foresight's HMT GC2 to measure rate of closure or ROC". "Some of those data points look quite low to be believable. Can you provide some details on the graph, so that it can be critiqued to the same level as Phil’s thesis?""Handle twist velocity will be at least 500 deg/s slower than ROC, and closer to 1000 deg/s slower for a tour player . That’s meaningful. It’s doubtful because I’ve never seen a Tour player with less than +650 deg/s for handle twist. Alex’s graph suggests negative twist. Doubtful."
*******Note: see last graph below which relates to SMK's comments above****** "For any swing, handle twist velocity will be meaningfully lower than ROC, but also highly correlated. Alex’s graph suggests some players are twisting the shaft in a way that would tend to reduce the RoC created from the fact the club is swung on an inclined plane. Doubtful."I'm unsure how HMT GC2 measures ROC but doesn't the below graph tend to demonstrate that golfers like Joe Durant, DJ, Rory, Furyk could be reducing their HTV using a 'Drive Hold' hand release action ? Their clubhead speeds vary from 104 - 122 mph yet their ROC seems to vary by only 350 degrees per second. SMK is assuming a high correlation with ROC and HTV approaching impact but cannot confirm that same correlation post impact (because of the low frequency sampling rate of the measurements systems). Therefore , next task is to find out more about this HMT GC2 system and check its integrity. Phil Cheetham graph : Note comment: Phil Cheetham acknowledged that using driving accuracy and basing it solely on hit fairway percentage is not a very complete view of things when it comes to accuracy because, for example, one is less likely to hit a fairway if they hit a 330 yard drive than a 250-yard drive due to the geometry of the shot. Margin for error is less. DG
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Post by dubiousgolfer on Sept 13, 2020 8:33:03 GMT -5
Here is what I found about GC2 from their website foresightsports.eu/It seems that their sampling frequency is 10,000 frames per second. They cost about £6k + vat. DG
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Post by imperfectgolfer on Sept 13, 2020 9:32:30 GMT -5
DG, You wrote-: " I find the above statement very confusing because I'm assuming most drivers have similar lie angles and although their shaft characteristics in terms of shaft bend and clubhead droop might differ , I cannot imagine their clubshaft swing planes being vastly different. The golfers might swing their arms/hands down different planes but surely the clubshaft plane at impact must be virtually the same? Therefore I don't understand how one can change their 'vertical planes' unless they change the lie angles of their drivers." Why must the VSP of driver swings be the same among all pro golfers - seeing that the ball is struck off a tee, and not the ground (where lie angle is very important)" Here are Phil Mickelson's and Sergio Garcia's driver swings. PM's VSP = 49 degrees and SG's VSP = 45 degrees. You also quoted SMK as follows-: " SMK comments relating to Alex Saary graph below using "Foresight's HMT GC2 to measure rate of closure or ROC".
"Some of those data points look quite low to be believable. Can you provide some details on the graph, so that it can be critiqued to the same level as Phil’s thesis?"
"Handle twist velocity will be at least 500 deg/s slower than ROC, and closer to 1000 deg/s slower for a tour player . That’s meaningful. It’s doubtful because I’ve never seen a Tour player with less than +650 deg/s for handle twist. Alex’s graph suggests negative twist. Doubtful." Where did you get that quote where SMK is commenting on Alex Saary's results? Are Alex Saary's results in the public sphere? Jeff.
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Post by dubiousgolfer on Sept 13, 2020 9:57:20 GMT -5
Dr Mann If both PM and SG had the same driver lie angle but PM swinging the clubshaft more vertical , wouldn't the 'normal' to the clubface point to the left and not down the ball target line? I got those quotes from searching on SMK's twitter account. The graph was included in one of the comments made by a person called Jeff Martin. For some reason the url link below doesn't show the twitter exchange - best to google search it. Jeff Martin @jeffygolf · 17 Apr Replying to @lukekerrdineen and @sashomackenzie Alex Saary's graph is also shown in full below http://instagr.am/p/-9ZmnlO5PX DG
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Post by imperfectgolfer on Sept 13, 2020 10:16:52 GMT -5
DG,
You wrote-: "If both PM and SG had the same driver lie angle but PM swinging the clubshaft more vertical, wouldn't the 'normal' to the clubface point to the left and not down the ball target line?"
I imagine that a different ball position and different degrees of forward shaft lean at impact can easily override any effect that a small difference of 5 degrees in VSP will have on the actual clubface direction at impact. Also, they presumably choose a driver that has a variable clubface hook angle to best suit their individual swing action.
Jeff.
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Post by Richie Hunt on Mar 27, 2022 23:33:17 GMT -5
I talked to Dr. Cheetham about getting his Rate of Closure data on Tour players to see if I could see if there was any correlation between RoC and any type of performance metric for Tour players.
Using Hit Fairway Percentage was a terribly flawed idea for the following reasons:
1. It does not measure the degrees offline the shot was hit. Thus a short hitter could miss by 3 degrees and a golfer like Bryson could miss by 2 degrees on the same hole and Bryson could end up missing the fairway because he hit the ball 70 yards further and the geometry caused him to miss the fairway, but in reality Bryson was more accurate and likely gained a sizable advantage off the tee.
2. The hit fairway percentage is not properly adjusted for the golfer's schedule. A place like Torrey Pines has roughly sub-50% fairways hit by the field every year whereas Muirfield Village has a 70%+ hit fairways by the field
I'm afraid that Mike Finney and Brian Manzella got in Dr. Cheetham's ear (even though I told Dr. Cheetham that I would hand over all of the data and math behind this before I would publish anything) and I never got the data from Dr. Cheetham.
In recent years data using the PGA Tour Tracker2 system, I've discovered the following.
1. With the driver, the Tour is about 50/50 split between players that consistently hit fades vs. those that consistently hit dras.
2. With the irons, it's more like 75% hit draws and 25% hit fades. I presume that's due to the geometry from the attack angles that can make it more 'natural' to hit a draw with an iron.
3. There are about 5-10% of the players that play more or less for a straight shot with the driver and then if it happens to fall left or fall right they can still find the fairway. From looking at the data, this is not a favorable way to drive the ball because it's not very predictable and thus has a tendency to be more inaccurate. That's unless the player is generating elite ball speed (178+ mph).
4. With the irons it's very rare to find a player that plays for a straight shot and is 'okay' with the ball landing left or right.
5. There's a trend that shows how important the short-push side miss is to iron play proficiency. Essentially, everybody on Tour has a miss with the irons that ends up well short of the hole (10+ yards) and misses well to the push side (right miss for righties, left miss for lefties...about 10+ yards).
Even shots that miss the hole location to the push side by 10-feet to 30-feet (more of a moderate push-side miss), the majority of them end up short of the hole.
For the best iron players on Tour, their misses to the right of the target (10+ feet)...about 50% of them will end up short. ~35% of those push side misses will end up pin high (within 10-feet distance wise to the hole) and ~15% will miss long (more than 10-feet long of the hole).
Compare to that to the elite iron players' pull side misses (10+ feet or more to the pull side of the hole), only about 20% of the pull side misses will end up short of the hole (10+ feet short of the hole) and about 40% will end up 'pin high' and 40% will end up long of the hole.
With weak iron players on Tour, about 60% of their push side misses end up short of the hole and then about 15-25% end up pin hand the other 15-25% up up short of the hole.
With the weak iron players on Tour, their pull side misses, their pull side misses end up short about 35% of the time pin high about 40% of the time and long about 25% of the time.
The short-push side miss for Tour players almost always accounts for the most strokes lost (cumulative) on approach shots and often times the most strokes lost per shot, regardless of their proficiency with on approach shots.
My thinking is that this is where Rate of Closure is most important for a Tour pro. I'd liked to get a much larger sample size of my research to further validate my claim, but I feel RoC is such a key piece to understanding iron play proficiency.
My thoughts are that Tour pros know how to square the clubface (relatively to their curve) on a fairly consistent basis with the irons. The problem for the high RoC players is that since their clubface has to rotate more to get square, they have to rely on timing more. The high RoC players may not time their closure rate as well and if they don't close the face enough, the face is open and the dynamic loft is higher. This causes the ball to miss towards the push-side and likely miss short. If they close the face too much, the face is closed and the dynamic loft may be lower causing the ball to miss to the pull side and travel further.
With the driver, because distance is such an important variable with regards to proficiency off the tee, Rate of Closure may not mean anywhere near as much as it does with irons where directional and distance control are paramount.
I'll post any updates in my research when I get them.
3JACK
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Post by imperfectgolfer on Apr 1, 2022 9:36:25 GMT -5
3jack, You wrote-: "The problem for the high RoC players is that since their clubface has to rotate more to get square, they have to rely on timing more. The high RoC players may not time their closure rate as well and if they don't close the face enough, the face is open and the dynamic loft is higher. This causes the ball to miss towards the push-side and likely miss short." You seem to be implying that a high clubface ROC measured at impact is causally associated with a need to have more clubface closing happening pre-impact in the later downswing. That would mean that pro golfers who have a weak lead hand grip, and who therefore need to have a lot of lead forearm supination happening in their late's downswing's PA#3 release action, will likely have a high clubface ROC at impact. By contrast, pro golfers who have a very strong lead hand grip will then likely have a low clubface ROC at impact because they do not need to supinate their lead forearm much in their later downswing. However, I know of no scientific evidence that shows this causal association between the strength of the lead hand grip and the clubface ROC measured at impact. Do you have any such evidence? I think that it is possible to have a low clubface ROC through impact even if a pro golfer adopts a weak lead hand grip. Consider an example - featuring Jon Rahm. Jon Rahm's 3-D graph. The blue graph is his lead forearm supination graph, and it shows that he has a very steep graph pre-impact because he uses a weak lead hand grip. That causes a high clubface ROC pre-impact.
However, the yellow arrow points at a plateau in that blue graph at impact, and if it actually happens through impact that would result in a very low clubface ROC through impact. Here are capture images of Jon Rahm's clubface through the impact zone. Face-on DTL Note that he keeps the clubface square to the clubhead arc sugesting a very low clubface ROC between P7 => P7.2. That suggests that he may have a low clubface ROC at impact despite having a high clubface ROC between P6.5 => P7. Do you know what's his clubface ROC measurement at impact? Jeff.
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Post by Richie Hunt on Apr 10, 2022 22:46:18 GMT -5
I don't know Rahm's RoC. I do know that historically his biggest weakness ballstriking wise has come from 125-175 yards, but he is typically excellent from 175-225 yards. I have often wondered if his spin loft was too high and that may cause spin control issues and he may 'air-mail' some shots from that distance.
But that's part of the problem with my hypothesis...we don't have the RoC data with irons. My thinking is that RoC plays a large role in iron play, but there are other factors, particularly depending on the grip, that play a role.
Dr. MacKenzie did tell me that Viktor Hovland has the lowest RoC of any player he has measured. Not by coincidence, Hovland ranks 2nd in Strokes Gained - Approach and having researched his iron shots, he does not hit that short-push side miss very often.
One factor my research is showing is the importance of trajectory. It's helpful to hit the irons high because of front 1/3rd pin locations on shots from 170+ yards. But also, players that hit it higher and curve the ball right-to-left tend to fare better on pin locations on the right 1/3rd of the green and vice versa for high ball, left-to-right curvature golfers.
Although one can hit it too high (i.e. Jason Day, Jamie Lovemark from 2015-2017, etc). The mean apex height on Tour is about 100-feet. Hitting it lower than 95-feet can become a problem for players and hitting it higher than 125-feet can be a problem. A good Apex Height is around 105-120 feet.
So a player with a slightly higher RoC but hits the ball higher may be a more proficient iron player than a player with a slower RoC, but hits the ball too low.
RH
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