Shaft Lag

[hiroshiro]

One of the tenets of TGM is maintaining lag pressure through impact and beyond. It appears as if some believe that this is manifested by the clubshaft being stressed and bowing back away from the target (the shaft leading the clubhead) throughout the down stroke and through impact. However, just about every image I have seen taken by high speed cameras shows that the shaft is straight or bowed forward just prior to impact. (The clubhead may still be behind the hands, though.) This is explained as centrifugal force acting on the center of gravity of the clubhead which is often (and especially with woods) further back than the shaft axis.

I am not questioning that one should endeavour to "sustain the lag" through impact, or that it is possible to maintain pressure again PP#3 throughout the down stroke. I would, however, like to solicit the learned forum members' opinion whether sustaining the lag is manifested by the shaft bending backwards throughout the downstroke until the moment just prior to impact. (Clearly impact itself will cause the shaft to appear to bend back, but this is not what I am referring to.)

 

[Garth]

Show me a picture of a shaft bowed forward before impact.

 

[bbftx]

hiroshiro,
True Temper Shaft Lab has done lots of empirical measurements of shaft bending during the swing --- droop and lead/lag . Different shafts swung by different people can lead or lag at impact.
http://www.truetemper.com/shaftlab/profile.html

Wishon is also developing some excellent shaft modeling software that will be capable of using measurements from a variety of real shafts to use in calculating shaft bending behavior during different swings and the resulting ball trajectory.
http://www.twgolftech.com/randd/#now03

 

[hiroshiro]

I can't right now. I don't have anything in electronic form at hand. I will see if there is anything in my library that can be scanned.

Do you have any photos of the shaft bending backwards just prior to impact?

 

[hiroshiro]

quote:Originally posted by bbftx

hiroshiro,
True Temper Shaft Lab has done lots of empirical measurements of shaft bending during the swing --- droop and lead/lag . Different shafts swung by different people can lead or lag at impact.
http://www.truetemper.com/shaftlab/profile.html

Wishon is also developing some excellent shaft modeling software that will be capable of using measurements from a variety of real shafts to use in calculating shaft bending behavior during different swings and the resulting ball trajectory.
http://www.twgolftech.com/randd/#now03

bbftx:

Thank you for the links. I had my swing profiled by Shaft Lab a few years ago. I will have to dig out the results.

The profile they had for "John Golfer" showed a clubhead lead of 0.36" at impact. I could not discern from the the other profiles (single peak, double peak, ramp) whether or not the clubhead was leading or lagging at impact as the graphs were too small. However, in all profiles the club shaft is definitely "losing the lag" as it approaches impact. The text explaining lead/lag also seemed to indicate that the clubhead always leads at impact due to "spring back" of the shaft and "overshooting".

I couldn't find anything on the Wishon link that definitively answered my question. Please let me know if I missed something. I believe I read something by Wishon in the past that the clubhead always leads the shaft at impact. This is the theory behind achieving a higher launch angle by moving the COG of a driver head as far back as possible, and also why softer shafts tend to hit the ball higher. (Although I believe that a VERY soft shaft can have the opposite effect.)

hiro

 

[Garth]

quote:Originally posted by hiroshiro

I can't right now. I don't have anything in electronic form at hand. I will see if there is anything in my library that can be scanned.

Do you have any photos of the shaft bending backwards just prior to impact?

yeah... here's one.. http://redgoat.smugmug.com/gallery/83757/1/2912863 and you could look at just about any other swing sequence on that site and see the same thing.

 

[01ragtop]

There was a pic of Sergio on here awhile back that showed the shaft bending foward at impact. Brian mentioned that it was because the shaft was too stiff.

 

[hiroshiro]

quote:Originally posted by 01ragtop

There was a pic of Sergio on here awhile back that showed the shaft bending foward at impact. Brian mentioned that it was because the shaft was too stiff.

I missed that thread. Do you have a link?

I fail to see why too stiff a shaft would result in it bending forward prior to impact. Was there an accompanying explanation why that was?

hiro

 

[01ragtop]

I should have posted this in the other reply.
http://www.manzellagolfforum.com/forum/topic.asp?TOPIC_ID=333&SearchTerms=shaft,too,stiff

 

[hiroshiro]

quote:Originally posted by Garth

quote:Originally posted by hiroshiro

I can't right now. I don't have anything in electronic form at hand. I will see if there is anything in my library that can be scanned.

Do you have any photos of the shaft bending backwards just prior to impact?

yeah... here's one.. http://redgoat.smugmug.com/gallery/83757/1/2912863 and you could look at just about any other swing sequence on that site and see the same thing.

Unfortunately, I cannot view the sequence in your link as I do not have a password. I will ask for one to be sent to me.

In the meantime, I can refer you to some comments and photographs contained in "Search for the Perfect Swing", by Cochran and Stobbs. I realise that this book may not be the favourite of Homer-philes, but it is what I have at hand at the moment.

If I may at first refer to the text on page 211 which reads:

"In fact there is ample photographic evidence to suggest that - for good players and bad, for whippy shafts and stiff - the clubhead has already sprung forward to the limit of its travel by the time it strikes the ball."

The book goes on to reference figures 8:2 and 8:8. 8:2 is a photo of, I believe, Robt. T. Jones. 8:8 is a photo of Dai Rees. I would also refer you to the photo on page 25, as well as the Ben Hogan sequence on pages 74 and 75. The Hogan sequence is less clear as a strobe was not used, but the shaft is clearly not bending backwards as it approaches impact.

Whether or not one believes the authors' conclusions as written, what is shown in the photographs is self-evident, and the advantage of these photographs (excepting the Hogan sequence) is that a strobe was used to minimise the blur resulting from a too slow shutter.

Of course it could also be that all these players suffered from Clubhead Throwaway, which is why I am asking the question in the first instance.

hiro

 

[MizunoJoe]

quote:Originally posted by hiroshiro

quote:Originally posted by 01ragtop

There was a pic of Sergio on here awhile back that showed the shaft bending foward at impact. Brian mentioned that it was because the shaft was too stiff.

I missed that thread. Do you have a link?

I fail to see why too stiff a shaft would result in it bending forward prior to impact. Was there an accompanying explanation why that was?

hiro

A stiffer shaft, once lagged, springs back faster than a softer one. Ideally, the shaft should kick so that it's straight at impact. Too stiff a shaft causes the face to be closed at impact, while a too soft shaft will leave the face open because the head is still lagging the shaft at impact. One way to compensate for a too stiff shaft on the driver is an open face. Most tour players like an open face on their driver. The local Cleveland rep told me that David Toms uses a 3 deg open face driver, which could mean that his shaft kicks too soon, indicating that it's too stiff.

 

[hiroshiro]

quote:Originally posted by 01ragtop

I should have posted this in the other reply.
http://www.manzellagolfforum.com/forum/topic.asp?TOPIC_ID=333&SearchTerms=shaft,too,stiff

ragtop:

Thanks for the link.

I must confess that I thought it was inconclusive. The frame prior to impact showed the clubhead to be around 18" from the ball. Due to the distance yet to travel and the viewing angle available, the curvature in the shaft could be attributed to, and is more likely the result of "shaft droop".

hiro

 

[hiroshiro]

quote:Originally posted by Garth

Show me a picture of a shaft bowed forward before impact.

Found a decent one here:

http://www.manzellagolfforum.com/forum/topic.asp?TOPIC_ID=3187

 

[golfie]

quote:Originally posted by hiroshiro

quote:Originally posted by Garth

Show me a picture of a shaft bowed forward before impact.

Found a decent one here:

http://www.manzellagolfforum.com/forum/topic.asp?TOPIC_ID=3187

And here,

http://www.clubmaker-online.com/bj010r.html

 

[nevermind]

I'm with hiroshiro. Sustaining the lag pressure does not manifest itself in a backward bent shaft at impact. I don't think you can successfully argue against that.

Those who have studied these things say that the vast majority of golfers have a forward bending shaft at impact. I've also read that when a robot swings shafts of different flexes, there is no correlation b/w flex and dispersion. Results may vary in human tests, due to reasons other than flex.

 

[hiroshiro]

quote:Originally posted by golfie


And here,

http://www.clubmaker-online.com/bj010r.html

Thanks, golfie. I remember those from a few years back when I used to subscribe to ShopTalk.

hiro

 

[hiroshiro]

quote:Originally posted by MizunoJoe


A stiffer shaft, once lagged, springs back faster than a softer one. Ideally, the shaft should kick so that it's straight at impact. Too stiff a shaft causes the face to be closed at impact, while a too soft shaft will leave the face open because the head is still lagging the shaft at impact. One way to compensate for a too stiff shaft on the driver is an open face. Most tour players like an open face on their driver. The local Cleveland rep told me that David Toms uses a 3 deg open face driver, which could mean that his shaft kicks too soon, indicating that it's too stiff.

Sorry, MizunoJoe, but I don't believe that is the case. I don't pretend to completely understand shaft dynamics during the downswing, but they are fairly complicated. The initial shaft load during the transition from back stroke to down stroke occurs in a different plane than the shaft "kick" when the head approaches impact. This initial bend unloads and then the shaft probably loads/unloads in a different plane. The head leads the shaft not because of excessive spring back but because of the offset (rearward) center of gravity of the clubhead. Other things being equal, the softer the shaft, the more the head leads the shaft, leading to a greater dynamic loft at impact AND a more closed face. Therefore a SOFTER shaft tends to cause hooks, and a stiffer shaft tends to cause fades (and lower trajectories).

Tour pros tend to prefer open faces because their swings are ones that promote draws. (Is it true that most pros are Horizontal Hingers?) I sincerely doubt it is because their shafts are too stiff.

My personal opinion is that golfer should use as stiff a shaft as possible that still allows the golfer to "feel the clubhead" and maintain rhythm/tempo (not Homer's Rhythm in this case). A stiff shaft will minimise clubhead lead/lag (as well as clubhead droop)and should lead to greater consistency.

hiro

 

[hiroshiro]

quote:Originally posted by nevermind

I'm with hiroshiro. Sustaining the lag pressure does not manifest itself in a backward bent shaft at impact. I don't you can successfully argue against that.

Nevermind:

Do you feel it is possible to maintain lag pressure throughout the downstroke until impact despite having a shaft that is bending forward? This is really the crux of what I'm interested in.

hiro

 

[Jim Kobylinski]

I highly doubt David plays with a 3* open driver. VJ plays with drivers that are 3-4* open and he is on the only people who can swing his driver fairly well.

Most pro's like the driver faces open to allow for the longer closing of the face during horizontal hinging.

 

[MizunoJoe]

quote:Originally posted by hiroshiro

Other things being equal, the softer the shaft, the more the head leads the shaft, leading to a greater dynamic loft at impact AND a more closed face. Therefore a SOFTER shaft tends to cause hooks, and a stiffer shaft tends to cause fades (and lower trajectories).

Tour pros tend to prefer open faces because their swings are ones that promote draws. (Is it true that most pros are Horizontal Hingers?) I sincerely doubt it is because their shafts are too stiff.

That has been the "wisdom" for yrs, but I always wondered why the opposite was true for me. It is interesting that when people first try the Whippy flexible shaft golf club trainer, they leave it out to the right, until they slow down considerably and get the kick timed.

Shaft experts(which I am not) have made the claim that most people, including tour pros, use shafts which are too stiff. There are some good reasons for this - a stiffer shaft feel crisper, if you can load it, and, according to Bob Burns, a shaft expert, a stiffer shaft gives more distance than a softer one for a given head speed.

This has been discussed at length here some time ago, so you might do a search.