Tiger Woods driver shaft is TOO stiff

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Date: 02 Oct 2006 07:37:19
From:
Subject: Tiger Woods driver shaft is TOO stiff

I was checking around for good images of golf shafts bending during
a swing. Not easy, video cameras are too slow. You really need
a high speed image camera with good optics.

Nike is keting Tiger, and has just such a display.
http://www.nike.com/nikegolf/swingportrait/

Now, you can see the shaft flex. Look after the backswing
is completed.

When the hands are hip high, you can see the lag in flex
of the shaft. No surprise there.

As the driver clubhead in the image is nearly
covering Tiger's right foot, slightly before impact,
look at the shaft. It has already kicked, and the
clubhead is bent forward relative to the projection
of the shaft through the hands. It should
be kicking right around at impact so the shaft is
straight at impact. But not in Tiger's case. The shaft is
too stiff, and it kicked early and probably costs him
another 20 yards.

You can note that the shaft flexes again after impact, and
the clubhead again lags the hands.

Very poor club design. Tiger needs a substantially less
stiff shaft so the thing kicks at the right time.

I have no idea if that driver is one he uses regularly or was
just present for his photo shoot, but the camera use by NIKE
does allow a very nice capturing of shaft flex through a
golf swing.

-PA

Date: 04 Oct 2006 08:16:19
From: SKIPPER
Subject: Re: Tiger Woods driver shaft is TOO stiff

Thomas Prufer wrote:
> On Wed, 4 Oct 2006 06:45:31 -0400, "tin Levac" <vac3@REMOVEvideotron.ca>
> wrote:
>
> >That's just as impossible. I read the specs and there's 10 bits per pixel.
> >It's a little complex and I don't know how the camera is built but I have a
> >good idea nevertheless. The light data must travel from the SR-CMOS to the
> >processor to the memory. Each pixel is 10 bits wide and each bit must be
> >connected by a trace. The SR-CMOS is 1024x1024 at 10 bit each so that would
> >require over 10 million traces to connect all pixels so that they can be
> >captured simultaneously. Another thing, all traces would have to be exactly
> >the same length. Well, there isn't 10 million traces so it follows that all
> >pixels are captured in sequence.
>
> You are confusing reading the pixel data with exposing it.
>
> >Now, how fast is the shutter moving across the focal plane for 1/100,000?
> >Which way is the shutter moving, is it moving in the same direction as the
> >object or the opposite direction or what? Obviously, there isn't a
> >mechanical shutter but the sequence of pixels produces the same result as a
> >mechanical shutter moving across the focal plane.
>
> A shutter need not be mechanical. Bragg cells could work as a shutter and expose
> all pixels simultaneously. Or there's an electric "enable" signal.

Never mudwrestle with a pig. You'll never win. You just get all dirty,
and the pig enjoys it.

-PA

Date: 04 Oct 2006 17:41:51
From: Martin Levac
Subject: Re: Tiger Woods driver shaft is TOO stiff

"SKIPPER" <blakestah@gmail.com > wrote in message
news:1159974979.321583.84250@m7g2000cwm.googlegroups.com...
>
> Thomas Prufer wrote:
>> On Wed, 4 Oct 2006 06:45:31 -0400, "tin Levac"
>> <vac3@REMOVEvideotron.ca>
>> wrote:
<snip >
>>> Never mudwrestle with a pig. You'll never win. You just get all dirty,
> and the pig enjoys it.
>
> -PA
>

Obviously, you are refering to me.

If that's what you think of me based only on what I wrote, imagine what
others think of you based on your last comment.

tin Levac

Date: 04 Oct 2006 03:51:18
From: SKIPPER
Subject: Re: Tiger Woods driver shaft is TOO stiff

That's what I get, too, 0.558 mm...

At the clubhead...

A fraction of that at the hands.

Of course, this has also been supported by strobe camera
work which lacks that limitation.

But that was only part of the argument...that the snapshots
supported a reverse kick better than they support a forward
kick.

The more compelling evidence is the relation between small changes
in flex, and ball flight patterns.

A stiffer shaft will kick earlier. This will turn a straight shot into
a
high hook if the shaft is kicking through the ball. And it will turn a
straight shot into a low slice if the shaft reverse kicks.

I suspect that the stiffnesses used are simply close to a harmonic
of the swing period so that the club is straight at impact. By
engineering
a shaft stiff enough to be kicking through the ball, the clubhead speed
should improve a bit without loss of accuracy. This would make the
club natural frequency close to 450 Hz or cpm.

It is also possible the club is supposed to reverse kick for a very
good reason that I don't understand...

-PA

Thomas Prufer wrote:
> On Wed, 4 Oct 2006 03:57:00 -0400, "tin Levac" <vac3@REMOVEvideotron.ca>
> wrote:
>
> >A true snap shot would be all segments of the image being captured in no
> >period of time and that's impossible.
>
> Eh? I'd say a true snap shot would be all pixels captured in a finite period of
> time, but simultaneously: the same period of time for all pixels.
>
> Anyway, if my sums are right, something at 125 mph moves half a millimeter in
> 1/100.000 of a second.
>
>
> Thomas Prufer

Date: 03 Oct 2006 23:03:38
From: Martin Levac
Subject: Re: Tiger Woods driver shaft is TOO stiff

<blakestah@gmail.com > wrote in message
news:1159799839.662988.141710@i3g2000cwc.googlegroups.com...
>I was checking around for good images of golf shafts bending during
> a swing. Not easy, video cameras are too slow. You really need
> a high speed image camera with good optics.
>
> Nike is keting Tiger, and has just such a display.
> http://www.nike.com/nikegolf/swingportrait/
>
> Now, you can see the shaft flex. Look after the backswing
> is completed.
>
> When the hands are hip high, you can see the lag in flex
> of the shaft. No surprise there.
>
> As the driver clubhead in the image is nearly
> covering Tiger's right foot, slightly before impact,
> look at the shaft. It has already kicked, and the
> clubhead is bent forward relative to the projection
> of the shaft through the hands. It should
> be kicking right around at impact so the shaft is
> straight at impact. But not in Tiger's case. The shaft is
> too stiff, and it kicked early and probably costs him
> another 20 yards.
>
> You can note that the shaft flexes again after impact, and
> the clubhead again lags the hands.
>
> Very poor club design. Tiger needs a substantially less
> stiff shaft so the thing kicks at the right time.
>
> I have no idea if that driver is one he uses regularly or was
> just present for his photo shoot, but the camera use by NIKE
> does allow a very nice capturing of shaft flex through a
> golf swing.
>
> -PA
>

The images that you analyse are not an accurate copy of the object that they
captured. More to the point, they are not an accurate copy of the movement
of the object that they captured. Your analysis is invalid.

Since all subsequent posts are also relying on the same images without
consideration, they can all be considered invalid.

The camera that is used is purported to be a Phantom v5 which is touted as
being able to capture 4000 frames per second. How long does it take for each
frame to be captured? It is safe to say that it takes time, regardless of
the amount of time. If the object being captured was stationary, it would
make no difference whatsoever but that is clearly not the case. It is
impossible to capture the complete object in the same fraction of time. The
image is captured in segments at different times. Since the object being
captured is moving across the focal plane and segments are captured at
different times, it follows that the result will be an effect of bending.
The first segment will be frozen on the image, the next segment will be
frowen a little later on the same image, the next segment and so on until
the whole image is filled. When the last segment is captured, the first
segment has had time to move further across the focal plane but since it was
captured already, it is not shown in its current position but in its past
position instead.

The object in question being analysed is a golf club shaft and we all know
that shafts are sold according to flex amongst other aspects. Since there is
real observed effect that will produce an optical illusion of bending and
the shaft is known to be bendable, it follows that what you see is obviously
mistaken for one another. Any conclusion that you drew based on these images
are based on incorrect data therefore those conclusions are invalid.

tin Levac

Date: 04 Oct 2006 16:54:38
From: david s-a
Subject: Re: Tiger Woods driver shaft is TOO stiff

tin Levac wrote:

> The camera that is used is purported to be a Phantom v5 which is touted as
> being able to capture 4000 frames per second. How long does it take for each
> frame to be captured? It is safe to say that it takes time, regardless of
> the amount of time. If the object being captured was stationary, it would
> make no difference whatsoever but that is clearly not the case. It is
> impossible to capture the complete object in the same fraction of time. The
> image is captured in segments at different times. Since the object being
> captured is moving across the focal plane and segments are captured at
> different times, it follows that the result will be an effect of bending.
> The first segment will be frozen on the image, the next segment will be
> frowen a little later on the same image, the next segment and so on until
> the whole image is filled. When the last segment is captured, the first
> segment has had time to move further across the focal plane but since it was
> captured already, it is not shown in its current position but in its past
> position instead.
>

This is not entirely true. The nature of the SR-CMOS sensor and the
software controlling it in the Phantom v5 is such that it is a true
'snapshot' or synchronous shutter camera, each frame reflecting a full
image at each selected point in time. It is not a 'rolling' shutter
camera and it most certainly does not have the 'roll through' effect
that you are describing. This particular camera will record 4000 images
per second on a selected 512x512 pixel array.....but it can record 1200
images per second on the full 1024x1024 pixel array.The Phantom's
SR-CMOS sensor actually allows continuously variable shutter speeds down
to 10 micro seconds (1/100,000 second) with an option to 5 micro
seconds. This shutter is a true "snap shot," or synchronous shutter.

This would seem to make much of your post irrelevant.

cheers
david

Date: 04 Oct 2006 03:57:00
From: Martin Levac
Subject: Re: Tiger Woods driver shaft is TOO stiff

"david s-a" <dsantwyk@bigpond.net.au > wrote in message
news:4oh45jFeg19jU1@individual.net...
> tin Levac wrote:
>
>
>> The camera that is used is purported to be a Phantom v5 which is touted
>> as being able to capture 4000 frames per second. How long does it take
>> for each frame to be captured? It is safe to say that it takes time,
>> regardless of the amount of time. If the object being captured was
>> stationary, it would make no difference whatsoever but that is clearly
>> not the case. It is impossible to capture the complete object in the same
>> fraction of time. The image is captured in segments at different times.
>> Since the object being captured is moving across the focal plane and
>> segments are captured at different times, it follows that the result will
>> be an effect of bending. The first segment will be frozen on the image,
>> the next segment will be frowen a little later on the same image, the
>> next segment and so on until the whole image is filled. When the last
>> segment is captured, the first segment has had time to move further
>> across the focal plane but since it was captured already, it is not shown
>> in its current position but in its past position instead.
>>
>
>
> This is not entirely true. The nature of the SR-CMOS sensor and the
> software controlling it in the Phantom v5 is such that it is a true
> 'snapshot' or synchronous shutter camera, each frame reflecting a full
> image at each selected point in time. It is not a 'rolling' shutter camera
> and it most certainly does not have the 'roll through' effect that you are
> describing. This particular camera will record 4000 images per second on a
> selected 512x512 pixel array.....but it can record 1200 images per second
> on the full 1024x1024 pixel array.The Phantom's SR-CMOS sensor actually
> allows continuously variable shutter speeds down to 10 micro seconds
> (1/100,000 second) with an option to 5 micro seconds. This shutter is a
> true "snap shot," or synchronous shutter.
>
> This would seem to make much of your post irrelevant.
>
> cheers
> david

Yes, what I wrote is entirely true and it applies to all cameras. What your
wrote is simply a c&p from the manufacturer's website. You know what I think
of manufacturer's information.

The real observed effect I mentioned will show most obviously if 4 cameras
are used. Each positioned at a rotated 90* angle from the next, all looking
at the same object from the same angle, all capturing the same sequence of
action. Then compare the result of each with each other to look at the
effect. Another method is the rotating disc with straight lines painted on
it. You can use a single camera and this has the benefit of giving you a
bend rating for the camera's shutter speed at speed of the object. I'm
almost certain we will never see such tests of the camera for fear that it
shows the flaws.

For the phantom to be a true synchronous shutter camera, all pixels would
have to capture each of their segment of the image during the exact same
fraction of time. That isn't what happens in fact. What happens instead is
that each pixel captures its segment in sequence very very quickly but still
in sequence over a period of 1/100,000 of a second. It is stated clearly in
the sales pitch on the manufacturer's website. Didn't you read?

A true snap shot would be all segments of the image being captured in no
period of time and that's impossible.

If you doubt the validity of a statement, state the contrary to look for
flaws. The simplest example is: I am, I am not. Select the one that's true,
discard the one that's not. This is a common method of analysis that's
rather rare on this newsgroup.

Cheers.

tin Levac

Date: 04 Oct 2006 11:53:58
From: Thomas Prufer
Subject: Re: Tiger Woods driver shaft is TOO stiff

On Wed, 4 Oct 2006 03:57:00 -0400, "tin Levac" <vac3@REMOVEvideotron.ca >
wrote:

>A true snap shot would be all segments of the image being captured in no
>period of time and that's impossible.

Eh? I'd say a true snap shot would be all pixels captured in a finite period of
time, but simultaneously: the same period of time for all pixels.

Anyway, if my sums are right, something at 125 mph moves half a millimeter in
1/100.000 of a second.

Thomas Prufer

Date: 04 Oct 2006 06:45:31
From: Martin Levac
Subject: Re: Tiger Woods driver shaft is TOO stiff

"Thomas Prufer" <prufer.public@mnet-online.de.invalid > wrote in message
news:9v07i21j6i7n18mbhre8b8q69a0q5o6qu8@4ax.com...
> On Wed, 4 Oct 2006 03:57:00 -0400, "tin Levac"
> <vac3@REMOVEvideotron.ca>
> wrote:
>
>>A true snap shot would be all segments of the image being captured in no
>>period of time and that's impossible.
>
> Eh? I'd say a true snap shot would be all pixels captured in a finite
> period of
> time, but simultaneously: the same period of time for all pixels.
>

That's just as impossible. I read the specs and there's 10 bits per pixel.
It's a little complex and I don't know how the camera is built but I have a
good idea nevertheless. The light data must travel from the SR-CMOS to the
processor to the memory. Each pixel is 10 bits wide and each bit must be
connected by a trace. The SR-CMOS is 1024x1024 at 10 bit each so that would
require over 10 million traces to connect all pixels so that they can be
captured simultaneously. Another thing, all traces would have to be exactly
the same length. Well, there isn't 10 million traces so it follows that all
pixels are captured in sequence.

> Anyway, if my sums are right, something at 125 mph moves half a millimeter
> in
> 1/100.000 of a second.
>
>
> Thomas Prufer

Yes, that's what I found as well.

Now, how fast is the shutter moving across the focal plane for 1/100,000?
Which way is the shutter moving, is it moving in the same direction as the
object or the opposite direction or what? Obviously, there isn't a
mechanical shutter but the sequence of pixels produces the same result as a
mechanical shutter moving across the focal plane.

Do we know at which shutter speed the images that are being discussed have
been captured? Do we know at which frame rate? All I know is what was stated
on either website, there is no particular data to the effect.

tin Levac

Date: 04 Oct 2006 13:40:13
From: Thomas Prufer
Subject: Re: Tiger Woods driver shaft is TOO stiff

On Wed, 4 Oct 2006 06:45:31 -0400, "tin Levac" <vac3@REMOVEvideotron.ca >
wrote:

>That's just as impossible. I read the specs and there's 10 bits per pixel.
>It's a little complex and I don't know how the camera is built but I have a
>good idea nevertheless. The light data must travel from the SR-CMOS to the
>processor to the memory. Each pixel is 10 bits wide and each bit must be
>connected by a trace. The SR-CMOS is 1024x1024 at 10 bit each so that would
>require over 10 million traces to connect all pixels so that they can be
>captured simultaneously. Another thing, all traces would have to be exactly
>the same length. Well, there isn't 10 million traces so it follows that all
>pixels are captured in sequence.

You are confusing reading the pixel data with exposing it.

>Now, how fast is the shutter moving across the focal plane for 1/100,000?
>Which way is the shutter moving, is it moving in the same direction as the
>object or the opposite direction or what? Obviously, there isn't a
>mechanical shutter but the sequence of pixels produces the same result as a
>mechanical shutter moving across the focal plane.

A shutter need not be mechanical. Bragg cells could work as a shutter and expose
all pixels simultaneously. Or there's an electric "enable" signal.

Thomas Prufer

Date: 04 Oct 2006 09:38:27
From: Martin Levac
Subject: Re: Tiger Woods driver shaft is TOO stiff

"Thomas Prufer" <prufer.public@mnet-online.de.invalid > wrote in message
news:gq67i29t53pgghjc89opj2lnce38vuk6co@4ax.com...
> On Wed, 4 Oct 2006 06:45:31 -0400, "tin Levac"
> <vac3@REMOVEvideotron.ca>
> wrote:
>
>>That's just as impossible. I read the specs and there's 10 bits per pixel.
>>It's a little complex and I don't know how the camera is built but I have
>>a
>>good idea nevertheless. The light data must travel from the SR-CMOS to the
>>processor to the memory. Each pixel is 10 bits wide and each bit must be
>>connected by a trace. The SR-CMOS is 1024x1024 at 10 bit each so that
>>would
>>require over 10 million traces to connect all pixels so that they can be
>>captured simultaneously. Another thing, all traces would have to be
>>exactly
>>the same length. Well, there isn't 10 million traces so it follows that
>>all
>>pixels are captured in sequence.
>
> You are confusing reading the pixel data with exposing it.

I'm not confused, are you?

Your statement presumes that there is a shutter on top of the SR-CMOS that
exposes the SR-CMOS. Is there such a shutter on the phantom v5 or isn't
there?

>
>>Now, how fast is the shutter moving across the focal plane for 1/100,000?
>>Which way is the shutter moving, is it moving in the same direction as the
>>object or the opposite direction or what? Obviously, there isn't a
>>mechanical shutter but the sequence of pixels produces the same result as
>>a
>>mechanical shutter moving across the focal plane.
>
> A shutter need not be mechanical. Bragg cells could work as a shutter and
> expose
> all pixels simultaneously. Or there's an electric "enable" signal.
>
> Thomas Prufer
>

And how are you going to synchronise the Bragg cell shutter with the SR-CMOS
data aquisition?

Again, your statement presumes that the digital camera has a shutter on top
of the SR-CMOS. Is there or isn't there such a shutter?

tin Levac

Date: 05 Oct 2006 09:07:40
From: Thomas Prufer
Subject: Re: Tiger Woods driver shaft is TOO stiff

On Wed, 4 Oct 2006 09:38:27 -0400, "tin Levac" <vac3@REMOVEvideotron.ca >
wrote:

>Your statement presumes that there is a shutter on top of the SR-CMOS that
>exposes the SR-CMOS. Is there such a shutter on the phantom v5 or isn't
>there?

No, it doesn't presume a shutter. One of the characteristics of CMOS is that
each pixel has a bit more circuitry than a CCD pixel. So telling all pixel
circuits to integrate the light from "now" to "then" is possible.

If I understand you correctly, you are asserting that these times must be
sequential. In that case you are wrong.

Thomas Prufer

Date: 05 Oct 2006 04:10:21
From: Martin Levac
Subject: Re: Tiger Woods driver shaft is TOO stiff

"Thomas Prufer" <prufer.public@mnet-online.de.invalid > wrote in message
news:aeb9i2t17gs4nb7e4okn37m56cmmov38cb@4ax.com...
> On Wed, 4 Oct 2006 09:38:27 -0400, "tin Levac"
> <vac3@REMOVEvideotron.ca>
> wrote:
>
>>Your statement presumes that there is a shutter on top of the SR-CMOS that
>>exposes the SR-CMOS. Is there such a shutter on the phantom v5 or isn't
>>there?
>
> No, it doesn't presume a shutter. One of the characteristics of CMOS is
> that
> each pixel has a bit more circuitry than a CCD pixel. So telling all pixel
> circuits to integrate the light from "now" to "then" is possible.
>
> If I understand you correctly, you are asserting that these times must be
> sequential. In that case you are wrong.
>
>
> Thomas Prufer

Elaborate, please.

tin Levac

Date: 05 Oct 2006 12:39:22
From: Thomas Prufer
Subject: Re: Tiger Woods driver shaft is TOO stiff

On Thu, 5 Oct 2006 04:10:21 -0400, "tin Levac" <vac3@REMOVEvideotron.ca >
wrote:

>Elaborate, please.

Have a look at the "SHUTTER" signal in the datasheet of the following CMOS chip:
<http://www.photonfocus.com/upload/application_notes/AN007_e_V1_1_CameraAcquisitionMode.pdf >

Or here:
<http://www.lot-oriel.com/site/site_down/co_cct135_deen.pdf >
where it says:

"Shutter: On-chip electronic shutter,
synchronous type (snapshot) and
rolling curtain type."

So a synchronous chip-wide shutter isn't a problem.

Thomas Prufer

Date: 05 Oct 2006 07:54:01
From: Martin Levac
Subject: Re: Tiger Woods driver shaft is TOO stiff

"Thomas Prufer" <prufer.public@mnet-online.de.invalid > wrote in message
news:dbn9i25vibercq22dsu34sjvsnm8f85fls@4ax.com...
> On Thu, 5 Oct 2006 04:10:21 -0400, "tin Levac"
> <vac3@REMOVEvideotron.ca>
> wrote:
>
>>Elaborate, please.
>
> Have a look at the "SHUTTER" signal in the datasheet of the following CMOS
> chip:
> <http://www.photonfocus.com/upload/application_notes/AN007_e_V1_1_CameraAcquisitionMode.pdf>
>
> Or here:
> <http://www.lot-oriel.com/site/site_down/co_cct135_deen.pdf>
> where it says:
>
> "Shutter: On-chip electronic shutter,
> synchronous type (snapshot) and
> rolling curtain type."
>
> So a synchronous chip-wide shutter isn't a problem.
>
>
> Thomas Prufer

I'm not convinced that there is such a thing as a synchronous digital
shutter. Nor am I convinced that it isn't a problem. Nor am I convinced that
it relates to the phantom v5.

Elaborate some more.

tin Levac

Date: 06 Oct 2006 08:27:44
From: Thomas Prufer
Subject: Re: Tiger Woods driver shaft is TOO stiff

On Thu, 5 Oct 2006 07:54:01 -0400, "tin Levac" <vac3@REMOVEvideotron.ca >
wrote:

>I'm not convinced that there is such a thing as a synchronous digital
>shutter. Nor am I convinced that it isn't a problem. Nor am I convinced that
>it relates to the phantom v5.
>
>Elaborate some more.

Skipper, looks like you were right.

Thomas Prufer

Date: 03 Oct 2006 10:30:37
From: SKIPPER
Subject: Re: Tiger Woods driver shaft is TOO stiff

Dave Lee wrote:

> Is a personal theory of yours or did you run into it somewhere? I've never
> seen this kind of matching stated as a straight-forward objective in
> clubfitting (and I am not a clubfitter, so I do not qualify as an expert).
> Natural frequency of the shaft/club is certainly used as a measure of
> stiffness, but in my limited experience it is a relative number only -
> generally relative to other shafts of similar/identical construction.

It can be found on various club-fitting websites...the general dogma
is that a a well-fitted shaft allows the clubhead to rebound through
the ball. The shaft should be straight at impact, and be
flexing forward, or kicking through the ball.

The same websites offer entirely illogical explanations as to why
a too-stiff club will result in a slice, and a too-flexy club will
result in a hook. Increases in stiffness will make the club kick
sooner,
not later, because it increases the fundamental frequency.

These observations are consistent if the club is reverse-kicking
through the ball. You are still matching the club frequency to the
swing, but the oscillation is out of phase, and this should cost
the golfer distance relative to a club that actually kicked through
the ball.

To correct the phase, the frequency of the club could be increased
by 50%, from roughly 300 Hz to 450 Hz. This would require a shaft
diameter increase of roughly 15%. The club should still be straight at
impact, but it should be kicking through impact, and not reverse
kicking.

-PA

Date: 03 Oct 2006 22:20:59
From: Dave Lee
Subject: Re: Tiger Woods driver shaft is TOO stiff

"SKIPPER" <blakestah@gmail.com > wrote in message
news:1159896637.443551.216890@i42g2000cwa.googlegroups.com...
>
> Dave Lee wrote:
>
> > Is a personal theory of yours or did you run into it somewhere? I've
never
> > seen this kind of matching stated as a straight-forward objective in
> > clubfitting (and I am not a clubfitter, so I do not qualify as an
expert).
> > Natural frequency of the shaft/club is certainly used as a measure of
> > stiffness, but in my limited experience it is a relative number only -
> > generally relative to other shafts of similar/identical construction.
>
> It can be found on various club-fitting websites...the general dogma
> is that a a well-fitted shaft allows the clubhead to rebound through
> the ball. The shaft should be straight at impact, and be
> flexing forward, or kicking through the ball.
>
> The same websites offer entirely illogical explanations as to why
> a too-stiff club will result in a slice, and a too-flexy club will
> result in a hook. Increases in stiffness will make the club kick
> sooner,
> not later, because it increases the fundamental frequency.
>
> These observations are consistent if the club is reverse-kicking
> through the ball. You are still matching the club frequency to the
> swing, but the oscillation is out of phase, and this should cost
> the golfer distance relative to a club that actually kicked through
> the ball.
>
> To correct the phase, the frequency of the club could be increased
> by 50%, from roughly 300 Hz to 450 Hz. This would require a shaft
> diameter increase of roughly 15%. The club should still be straight at
> impact, but it should be kicking through impact, and not reverse
> kicking.
>
> -PA
>

FWIW, the resources that I trust (such as Wishon and Tutelman) are careful
to say that softer shafts tend to create more draw, but that this is not
always the case.

Achieving a straight shaft at impact seems like a logical goal. I'm somewhat
puzzled as to why this isn't (directly) a part of shaft-fitting as it seems
to me to be relatively easy to monitor these days. I routinely capture my
swing at 1/2000 sec on a $250 digital camcorder. This freezes things pretty
well, although you only get a half dozen'ish frames per downswing. But it is
really simple to see your shaft around the impact position without spending
a bunch of money (assuming that you already have a firewire enabled
computer). Just take a handful of drivers (with different shafts) and maybe
four or five swings per club and you should get a pretty good idea of how
the shaft is acting for you. But I'm not aware of any clubfitter who does it
this way.

But I just don't see how you can do the analysis that you are trying to do.
Let me say first of all that I am not a mechanical engineer and have never
studied the dynamics of a beam under small deflection - I'm sure that it is
a very well studied phenomenon.

I'm guessing that enough simplifying assumptions reduce the system down to
probably a 2nd order linear differential equation. . There will be two
responses

1) The natural response
2) The response to the forcing function (varying torque applied to the shaft
by the swing)

I just don't see how you can solve this system to any useful degree without
including the forcing function and the system response to it.

dave

Date: 03 Oct 2006 10:17:33
From: greers
Subject: Re: Tiger Woods driver shaft is TOO stiff

Date: 03 Oct 2006 16:53:19
From: Kenny Stultz
Subject: Re: Tiger Woods driver shaft is TOO stiff

In article <1159872142.566377.112790@m7g2000cwm.googlegroups.com >,
blakestah@gmail.com says...
>
>
>Kenny Stultz wrote:
>
>> Be careful about hanging too much on that 290 cpm. That's the frequency
>> measurement you get for an ungripped club clamped tightly in a vise. That
>> same club's frequency with a grip installed and held by soft (by comparison
to
>> the clamp) human hands is a whole lot lower than 290 cpm.
>
>How is this possible?
>
>The oscillation is determined by the spring constant of the shaft
>and the weight of the clubhead, Adding dampening doesn't
>do a lot to shift the fundamental, but it can shift the magnitude
>of the dampening of the oscillation.
>
>-PA
>

You are correct about damping not changing the fundamental frequency a great
deal. You are also correct about the spring constant of the shaft and the
weight of the club head determining the nautral frequency of the shaft (the
weight of the shaft is factor also).

However, the effective spring constant of the shaft changes greatly with how
loosely or tightly the club is clamped.

--
Kenny Stultz - Troll and SPAM intolerant
RSG Rollcall: http://rec-sport-golf.com/members/?rollcall=stultzk
"Golf is the only sport where a precise knowledge of the Rules can
earn one a reputation for poor sportsmanship"

Date: 03 Oct 2006 08:03:52
From: Birdie Bill
Subject: Re: Tiger Woods driver shaft is TOO stiff

blakestah@gmail.com wrote:
> S McFarlane wrote:
> > <blakestah@gmail.com> wrote in message
> > news:1159822031.605875.124490@m73g2000cwd.googlegroups.com...
> > > It is clearly visible in the link I posted .
> > >
> > > It is from a special photo shoot to show off Tiger's swing and
> > > the Nike driver.
> > >
> > > As I said, it could be something other than the driver in his bag.
> > >
> >
> > If you feel you have detected an error in the fit of the shaft in the
> > picture to Tiger's swing, then you are safe to bet your bottom dollar that
> > it is not in his bag.
> >
> > The theoretical discussion of shaft flex and it's impact on end results is
> > definitely an interesting one, but it has given way to good old fashioned
> > empiricism as all scientific discussions must. Tiger Woods has probably
> > spent hundreds of hours on very high-tech measurement hardware and 100's of
> > thousands of dollars worth of shaft-Nike driver head combinations readily
> > available for data collection. The people who hand him the clubs for
> > testing likely have doctorates from MIT or equivalent.
>
> I can tell you right now that no one with an engineering doctorate from
> MIT or equivalent works in golf club design. They'd be doing well if
> they had someone with an MIT undergraduate degree.
>
> The best explanations I've seen are that the shaft "droops"
> from the centripetal acceleration - the hosel tries to "straighten out"
> from the force, and that due to rotation of the club through impact
> it appears as an inverse kick through impact.
>
> Which was something I hadn't thought of....thanks...

Do you understand conservation of angular momentum? If not,
I suggest you read up on it, and how it relates to the golf swing.
Once you understand that, then a lot of things which may
seem mysterious have obvious answers.

Date: 03 Oct 2006 08:00:54
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

Larry Bud wrote:
> > People think it is less kick if the shaft is stiffer, but in reality it
> > mostly makes the club kick earlier and earlier. If they made
> > a similar video of Tiger using a regular stiffness shaft, you
> > would see more clubhead lag on the downswing, and the club
> > would not return to straight before impact, it would instead
> > lag through impact, and he would slice everything.
>
> You've got it backward. Too stiff and you hit low cuts, too flexible
> and you hit high hooks.

this sort of leads into my confusion...

A stiffer shaft will have a higher frequency and will flex and
unflex faster.

So, if the standard is for the club to be kicking through impact,
then making the shaft stiffer will make the club kick earlier,
not later, and will make the club hit a high hook, not a low slice.

I'm not saying the empirical result is wrong. But it doesn't jibe
with the standard dogma that a shaft flexes, and then returns to
straight at impact.

Unless the standard way of matching shafts to golf swings
actually results in the shaft being straight, but reverse
kicking, through the ball.

In the downswing, does the shaft flex back, forward, and back
to a centered position at impact for the usual driver? This would
mean small increases in stiffness would lead to the club being
flexed back at impact ie: low slices, and small decreases in stiffness
leading to high hooks.

The standard frequencies used in clubmaking are close to 300 Hz,
which is a full period in 200 msec, roughly the length of a downswing.
If the full period matches the downswing length, then the club IS
reverse kicking through the ball.

Of course, the most important thing is that the shaft is straight. But
I gotta wonder....what if you used a frequency of 450 Hz...then the
club should go through 1.5 periods on the downswing, it would be
similarly
straight at impact, and kicking through the ball...or a frequency of
150
Hz, which would make the club flex back, and return to straight at
impact...
probably would feel super flexy though...but I bet the ball would
really fly further.

-PA

Date: 03 Oct 2006 06:55:08
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

Dave Lee wrote:

> I've looked at the video, but only on my laptop. I just don't see what you
> are seeing - maybe on a better monitor??

http://www.blakestah.com/golf/

There are 8 snapshots of the swing. What I noted was
Snapshots 1 through 3. Notable clubhead lag from shaft flex.

Snapshot 4. Shaft appears straight.

Snapshot 5. Shaft appears to be kicking forward. As has already been
noted, it is very tough from this angle to see if the shaft is bending
to
point the toe down, or if it is bending so the clubhead leads the
hands.
I think the toe-down explanation is more likely.

Snapshot 6. Shaft appears to be straightening. Again, could be toe-down
flex, and the shaft is rotating through the ball making the camera
blind
to flex from this angle.

Snapshot 7. Straight at impact.

Snapshot 8. Clubhead again lags hands, possibly from impact with the
ball. Possibly it is still toe-down, although the club does not appear
to
be rotated enough to make that visible.

I'm a total novice in trying to relate club frequency to flex during
the
swing, but it can't be that tough to figure out...I'm trying to
understand
what it is that should be seen during a golf swing wrt shaft flex, and
whether it is present in the very high quality snapshots that Nike
provided of Tiger's swing. I mean, someone must have, at some
point, stuck an accelerometer in the clubhead and another in the
grip to measure shaft flex quantitatively.

I still have a hard time reconciling snapshots 4-7 with the idea
that the shaft should be kicking forward (in addition to flexing
toe-down).
>From the angle some straightening clubhead lag should be visible
in addition to the toe-down flex, but if anything it is the opposite.
Really need another set of snapshots at a 90 degree angle at the
same time points.

-PA

Date: 03 Oct 2006 16:40:35
From: Dave Lee
Subject: Re: Tiger Woods driver shaft is TOO stiff

<blakestah@gmail.com > wrote in message
news:1159883708.022489.196100@i3g2000cwc.googlegroups.com...
>
> Dave Lee wrote:
>
> > I've looked at the video, but only on my laptop. I just don't see what
you
> > are seeing - maybe on a better monitor??
>
> http://www.blakestah.com/golf/
>
> There are 8 snapshots of the swing. What I noted was
> Snapshots 1 through 3. Notable clubhead lag from shaft flex.
>
> Snapshot 4. Shaft appears straight.
>
> Snapshot 5. Shaft appears to be kicking forward. As has already been
> noted, it is very tough from this angle to see if the shaft is bending
> to
> point the toe down, or if it is bending so the clubhead leads the
> hands.
> I think the toe-down explanation is more likely.
>
> Snapshot 6. Shaft appears to be straightening. Again, could be toe-down
> flex, and the shaft is rotating through the ball making the camera
> blind
> to flex from this angle.
>
> Snapshot 7. Straight at impact.
>
> Snapshot 8. Clubhead again lags hands, possibly from impact with the
> ball. Possibly it is still toe-down, although the club does not appear
> to
> be rotated enough to make that visible.
>
> I'm a total novice in trying to relate club frequency to flex during
> the
> swing, but it can't be that tough to figure out...I'm trying to
> understand
> what it is that should be seen during a golf swing wrt shaft flex, and
> whether it is present in the very high quality snapshots that Nike
> provided of Tiger's swing. I mean, someone must have, at some
> point, stuck an accelerometer in the clubhead and another in the
> grip to measure shaft flex quantitatively.
>
> I still have a hard time reconciling snapshots 4-7 with the idea
> that the shaft should be kicking forward (in addition to flexing
> toe-down).
> >From the angle some straightening clubhead lag should be visible
> in addition to the toe-down flex, but if anything it is the opposite.
> Really need another set of snapshots at a 90 degree angle at the
> same time points.
>
>
> -PA
>

I suppose that this could be analyzed with the appropriate data. But there
is significant loading on the shaft during the swing and this varies quite a
bit during the swing and from golfer to golfer (and quite likely from swing
to swing with the same golfer/club). I would think that you would pretty
much have to include this loading profile in the analysis. Getting that data
would be do-able, but not with anything that I have in my workshop.

Theodore Jorgensen's "The Physics of Golf" is an interesting read along
these lines as well as the older/classic "Search for the Perfect Swing" by
Cochran and Stobbs.

dave

Date: 04 Oct 2006 16:26:48
From: david s-a
Subject: Re: Tiger Woods driver shaft is TOO stiff

Dave Lee wrote:

>>
>
>
> I suppose that this could be analyzed with the appropriate data. But there
> is significant loading on the shaft during the swing and this varies quite a
> bit during the swing and from golfer to golfer (and quite likely from swing
> to swing with the same golfer/club). I would think that you would pretty
> much have to include this loading profile in the analysis. Getting that data
> would be do-able, but not with anything that I have in my workshop.
>

The True Temper 'Shaft Lab' system provides just that. The test system I
subjected myself to quite some years ago involved a specially rigged
'standard' shafted club incorporating various strain guage and
accelerometer sensors. These measured shaft forces in a variety of
directions throughout the swing and when presented as a function of
time, showed a distinct 'fingerprint' of my swing. Everyone's
'fingerprint' is unique, and there appears to be no ideal profile. It is
the task of the clubfitter to match an existing shaft to your own unique
'fingerprint'. In my case the graph showed a significant loading in the
early part of the swing with a steadily diminishing force but with a
noticeable 'hump' immediately prior to impact.

The interesting thing about it was that at the time the system
'recommended' a stiff flex EI 70 in my 12� GBB head. A simple 'waggle'
with that setup worried me.....it felt far too stiff. However, when put
into action on the course that club played better than any other driver
I have ever used...a friend who is a much better, younger, and stronger
golfer than I am still uses it today as his 'goto' club!

cheers
david

Date: 04 Oct 2006 11:44:45
From: Dave Lee
Subject: Re: Tiger Woods driver shaft is TOO stiff

"david s-a" <dsantwyk@bigpond.net.au > wrote in message
news:4oh2hdFehveaU1@individual.net...
> Dave Lee wrote:
>
> >>
> >
> >
> > I suppose that this could be analyzed with the appropriate data. But
there
> > is significant loading on the shaft during the swing and this varies
quite a
> > bit during the swing and from golfer to golfer (and quite likely from
swing
> > to swing with the same golfer/club). I would think that you would pretty
> > much have to include this loading profile in the analysis. Getting that
data
> > would be do-able, but not with anything that I have in my workshop.
> >
>
>
> The True Temper 'Shaft Lab' system provides just that. The test system I
> subjected myself to quite some years ago involved a specially rigged
> 'standard' shafted club incorporating various strain guage and
> accelerometer sensors. These measured shaft forces in a variety of
> directions throughout the swing and when presented as a function of
> time, showed a distinct 'fingerprint' of my swing. Everyone's
> 'fingerprint' is unique, and there appears to be no ideal profile. It is
> the task of the clubfitter to match an existing shaft to your own unique
> 'fingerprint'. In my case the graph showed a significant loading in the
> early part of the swing with a steadily diminishing force but with a
> noticeable 'hump' immediately prior to impact.
>
> The interesting thing about it was that at the time the system
> 'recommended' a stiff flex EI 70 in my 12� GBB head. A simple 'waggle'
> with that setup worried me.....it felt far too stiff. However, when put
> into action on the course that club played better than any other driver
> I have ever used...a friend who is a much better, younger, and stronger
> golfer than I am still uses it today as his 'goto' club!
>
> cheers
> david

Interesting - I'm curious as to what you were playing before the analysis
was completed.

dave

Date: 05 Oct 2006 08:41:42
From: david s-a
Subject: Re: Tiger Woods driver shaft is TOO stiff

Dave Lee wrote:
> "david s-a" <dsantwyk@bigpond.net.au> wrote in message
> news:4oh2hdFehveaU1@individual.net...
>
>>Dave Lee wrote:
>>
>>
>>>
>>>I suppose that this could be analyzed with the appropriate data. But
>
> there
>
>>>is significant loading on the shaft during the swing and this varies
>
> quite a
>
>>>bit during the swing and from golfer to golfer (and quite likely from
>
> swing
>
>>>to swing with the same golfer/club). I would think that you would pretty
>>>much have to include this loading profile in the analysis. Getting that
>
> data
>
>>>would be do-able, but not with anything that I have in my workshop.
>>>
>>
>>
>>The True Temper 'Shaft Lab' system provides just that. The test system I
>>subjected myself to quite some years ago involved a specially rigged
>>'standard' shafted club incorporating various strain guage and
>>accelerometer sensors. These measured shaft forces in a variety of
>>directions throughout the swing and when presented as a function of
>>time, showed a distinct 'fingerprint' of my swing. Everyone's
>>'fingerprint' is unique, and there appears to be no ideal profile. It is
>>the task of the clubfitter to match an existing shaft to your own unique
>>'fingerprint'. In my case the graph showed a significant loading in the
>>early part of the swing with a steadily diminishing force but with a
>>noticeable 'hump' immediately prior to impact.
>>
>>The interesting thing about it was that at the time the system
>>'recommended' a stiff flex EI 70 in my 12� GBB head. A simple 'waggle'
>>with that setup worried me.....it felt far too stiff. However, when put
>>into action on the course that club played better than any other driver
>>I have ever used...a friend who is a much better, younger, and stronger
>>golfer than I am still uses it today as his 'goto' club!
>>
>>cheers
>>david
>
>
> Interesting - I'm curious as to what you were playing before the analysis
> was completed.
>
> dave
>
>

I erred! The club was a 12* BiggestBB (Not GBB). I was also playing
Callaways before that...Warbirds etc...with Callaway shafts (regular and
firm)...IIRC RCH 60's, RCH 90s and RCH 96's. At one stage I had the full
range..... driver, 'deuce', 3, 3+, 4, 5, 7 ('Heaven wood') and 9
('Divine 9')!. I've still got all those old heads somewhere. Not great
shafts....just OEM off the shelf. I think my earliest club of that era
was a Yonex fully composite head/shaft combo....not a great club either!
I'm just a victim of keting hype!

cheers
david

Date: 03 Oct 2006 05:21:05
From: dsc
Subject: Re: Tiger Woods driver shaft is TOO stiff

S McFarlane wrote:
> <blakestah@gmail.com> wrote in message
> news:1159827118.261326.161330@k70g2000cwa.googlegroups.com...
> > The saga continues...Nike says
> > ---------------------
> > We appreciate your detailed feedback regarding Tiger's shaft selection.
> > Please keep in mind, that Tiger is the one who selected the Diamana 83
> > for his SQ driver. We do not have any say as to which shaft he uses
> > for his club. I would recommend that you pass along this feedback to
> > his website at www.tigerwoods.com.
> > ---------------------
> > We'll see where that goes.
>
>
> Very interesting. I wish I'd seen that before blowing so much wind. I
> wonder if it's true that Nike has no say whatsoever in the area of shaft
> selection. I find that hard to believe.

I don't find that hard to beleive at all. Tiger gets what Tiger
wants... simple as that. But, I wouldn't be suprised that if some other
shaft was is in his diver it would be disguised as a Nike shaft either.

Date: 03 Oct 2006 03:42:22
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

Kenny Stultz wrote:

> Be careful about hanging too much on that 290 cpm. That's the frequency
> measurement you get for an ungripped club clamped tightly in a vise. That
> same club's frequency with a grip installed and held by soft (by comparison to
> the clamp) human hands is a whole lot lower than 290 cpm.

How is this possible?

The oscillation is determined by the spring constant of the shaft
and the weight of the clubhead, Adding dampening doesn't
do a lot to shift the fundamental, but it can shift the magnitude
of the dampening of the oscillation.

-PA

Date: 03 Oct 2006 03:39:29
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

If the club period is 200 msec...

And the downswing takes 200 msec...

Then the shaft will lag in flex...then lead in flex...then
be at the neutral position at impact while it reverse
kicks...

If the club period is 400 msec, and the downswing takes
200 msec, then the club will flex back, and return, to
kick at impact.

Or maybe I am missing something in how club frequency
gets matched to swing periods...but it seems to me the
downswing time should be half a period of the club's
oscillation.

-PA

Dave Lee wrote:
> <blakestah@gmail.com> wrote in message
> news:1159804536.384764.5510@b28g2000cwb.googlegroups.com...
> >
> > Dave Lee wrote:
> > > <blakestah@gmail.com> wrote in message
> >
> > > For most golf swings if you want the clubhead to have less of a tendency
> to
> > > be 'kicked forward' at impact, you would use a stiffer shaft.
> >
> > The increased stiffness will make the club kick earlier.
> >
> > People tend to think that in the limit they really want the club to
> > stay
> > as straight as possible.
> >
> > But the image of Woods swinging makes it clear that the shaft bends
> > a LOT, even an ultra stiff shaft swung by Woods.
> >
> > You have the option of making a much heavier shaft, or of
> > tuning the oscillation so that the club is nearly straight at
> > impact. In Woods case, the club oscillates back, forward, and
> > is midway towards oscillating back again when Woods
> > hits impact.
> > snip
>
> I've looked at the video, but only on my laptop. I just don't see what you
> are seeing - maybe on a better monitor??
>
> But I don't see how it can happen. A typical professional golf swing
> downswing takes around 200 to 250 msec (source Cochran/Stobbs "Search for
> the Perfect Golf Swing"). A typical X flex 45" driver shaft would have a
> natural frequency of around 290 cpm (period of around 200 msec). I just
> don't see how it could go back, forth, and halfway back again (more than a
> full oscillation cycle) on the downswing.
>
> dave

Date: 03 Oct 2006 13:04:08
From: Dave Lee
Subject: Re: Tiger Woods driver shaft is TOO stiff

<blakestah@gmail.com > wrote in message
news:1159871969.498576.128280@m73g2000cwd.googlegroups.com...
>
> If the club period is 200 msec...
>
> And the downswing takes 200 msec...
>
> Then the shaft will lag in flex...then lead in flex...then
> be at the neutral position at impact while it reverse
> kicks...
>
> If the club period is 400 msec, and the downswing takes
> 200 msec, then the club will flex back, and return, to
> kick at impact.
>
> Or maybe I am missing something in how club frequency
> gets matched to swing periods...but it seems to me the
> downswing time should be half a period of the club's
> oscillation.
>
> -PA
>
>

I've just never seen shaft flex analyzed in this manner (directly). The
shaft is under significant load early in the swing, so it really has much
less time than 200 msec.

Is a personal theory of yours or did you run into it somewhere? I've never
seen this kind of matching stated as a straight-forward objective in
clubfitting (and I am not a clubfitter, so I do not qualify as an expert).
Natural frequency of the shaft/club is certainly used as a measure of
stiffness, but in my limited experience it is a relative number only -
generally relative to other shafts of similar/identical construction.

dave

Date: 03 Oct 2006 03:22:52
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

S McFarlane wrote:
> <blakestah@gmail.com> wrote in message
> news:1159822031.605875.124490@m73g2000cwd.googlegroups.com...
> > It is clearly visible in the link I posted .
> >
> > It is from a special photo shoot to show off Tiger's swing and
> > the Nike driver.
> >
> > As I said, it could be something other than the driver in his bag.
> >
>
> If you feel you have detected an error in the fit of the shaft in the
> picture to Tiger's swing, then you are safe to bet your bottom dollar that
> it is not in his bag.
>
> The theoretical discussion of shaft flex and it's impact on end results is
> definitely an interesting one, but it has given way to good old fashioned
> empiricism as all scientific discussions must. Tiger Woods has probably
> spent hundreds of hours on very high-tech measurement hardware and 100's of
> thousands of dollars worth of shaft-Nike driver head combinations readily
> available for data collection. The people who hand him the clubs for
> testing likely have doctorates from MIT or equivalent.

I can tell you right now that no one with an engineering doctorate from
MIT or equivalent works in golf club design. They'd be doing well if
they had someone with an MIT undergraduate degree.

The best explanations I've seen are that the shaft "droops"
from the centripetal acceleration - the hosel tries to "straighten out"
from the force, and that due to rotation of the club through impact
it appears as an inverse kick through impact.

Which was something I hadn't thought of....thanks...

-PA

Date: 03 Oct 2006 07:05:44
From: S McFarlane
Subject: Re: Tiger Woods driver shaft is TOO stiff

<blakestah@gmail.com > wrote in message
news:1159799839.662988.141710@i3g2000cwc.googlegroups.com...
>
> Very poor club design. Tiger needs a substantially less
> stiff shaft so the thing kicks at the right time.
>

You obviously haven't been paying attention during tin's sermons.

Scott

Date: 03 Oct 2006 10:01:29
From: david s-a
Subject: Re: Tiger Woods driver shaft is TOO stiff

Date: 02 Oct 2006 16:17:49
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

Jeff wrote:
> I'm sure Tiger has tried all combinations of shafts (both length and
> distance) and loft of drivers and picked the one that gives him the best
> combination of distance and accuracy.
>
>

Yes, but if stiffness X give you a straight shaft and a reverse
kick through the ball, than stiffness 1.33*X will give you a
straight shaft and a forward kick through the ball.

I'd bet money there is a significant measurable difference
in the two.

-PA

Date: 02 Oct 2006 16:15:57
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

RB wrote:

> I think that Wishon said 'clubhead lag' never happens jusr prior to
> impact. Harrison (maker of shafts ) claims it does happen. However I
> don't ever recall seeing a picture of anyone (not an Iron-Byron type
> machine) lagging a clubhead behind a shaft pre-impact.
>
> Clubhead *lead* is normal just prior to impact. Clubhead lag isn't.

Wishon said something to the extent that shafts don't oscillate
because the hands dampen it.

Obviously shafts do oscillate.

What I really want to know is whether the phenomena observed
in Tiger's swing is the norm...ie: is it typical that golf club shafts
are reverse kicking through the ball, or is it typical that golf club
shafts kick through the ball? Obviously in that one example from
Tiger it is clearly a reverse kick. There must be a really noticeable
difference in distance from a reverse and forward kick in the shaft...
but perhaps a shaft flexible enough to kick is just too flexible to
be aesthetically pleasing?

I had already throught of using a strobe, Jones was way way
ahead of me in using a strobe to freeze-frame on something
happening very fast.

-PA

Date: 02 Oct 2006 15:43:25
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

Date: 02 Oct 2006 15:20:04
From: The_Professor
Subject: Re: Tiger Woods driver shaft is TOO stiff

X-No-Archive: yes

blakestah@gmail.com wrote:
> I was checking around for good images of golf shafts bending during
snippit..

This post reminds me of the Buick commercial where the guy sends Tiger
a video telling him to practice swining with a broom to solve some
presumed flaw the guy sees in Tigers swing.

Date: 02 Oct 2006 22:17:19
From: Jeff
Subject: Re: Tiger Woods driver shaft is TOO stiff

I'm sure Tiger has tried all combinations of shafts (both length and
distance) and loft of drivers and picked the one that gives him the best
combination of distance and accuracy.

<blakestah@gmail.com > wrote in message
news:1159799839.662988.141710@i3g2000cwc.googlegroups.com...
>I was checking around for good images of golf shafts bending during
> a swing. Not easy, video cameras are too slow. You really need
> a high speed image camera with good optics.
>
> Nike is keting Tiger, and has just such a display.
> http://www.nike.com/nikegolf/swingportrait/
>
> Now, you can see the shaft flex. Look after the backswing
> is completed.
>
> When the hands are hip high, you can see the lag in flex
> of the shaft. No surprise there.
>
> As the driver clubhead in the image is nearly
> covering Tiger's right foot, slightly before impact,
> look at the shaft. It has already kicked, and the
> clubhead is bent forward relative to the projection
> of the shaft through the hands. It should
> be kicking right around at impact so the shaft is
> straight at impact. But not in Tiger's case. The shaft is
> too stiff, and it kicked early and probably costs him
> another 20 yards.
>
> You can note that the shaft flexes again after impact, and
> the clubhead again lags the hands.
>
> Very poor club design. Tiger needs a substantially less
> stiff shaft so the thing kicks at the right time.
>
> I have no idea if that driver is one he uses regularly or was
> just present for his photo shoot, but the camera use by NIKE
> does allow a very nice capturing of shaft flex through a
> golf swing.
>
> -PA
>

Date: 02 Oct 2006 17:16:06
From: RB
Subject: Re: Tiger Woods driver shaft is TOO stiff

blakestah@gmail.com wrote:
> I was checking around for good images of golf shafts bending during
> a swing. Not easy, video cameras are too slow. You really need
> a high speed image camera with good optics.
>
> Nike is keting Tiger, and has just such a display.
> http://www.nike.com/nikegolf/swingportrait/
>
> Now, you can see the shaft flex. Look after the backswing
> is completed.
>
> When the hands are hip high, you can see the lag in flex
> of the shaft. No surprise there.
>
> As the driver clubhead in the image is nearly
> covering Tiger's right foot, slightly before impact,
> look at the shaft. It has already kicked, and the
> clubhead is bent forward relative to the projection
> of the shaft through the hands. It should
> be kicking right around at impact so the shaft is
> straight at impact. But not in Tiger's case. The shaft is
> too stiff, and it kicked early and probably costs him
> another 20 yards.

What you are observing is not shaft kick, but the alignment of the
clubhead's vertical CG to the shaft axis. This axis does not run
through the shaft/hosel, but through a point somewhere in the middle of
the clubhead. It is quite normal. Grab a driver and suspend it by two
fingers at the end of the grip. You'll observe that the shaft does not
'hang' perfectly straight down. Under load, the shaft is bending to
compensate for loads placed on it during the swing. The CG alignment is
one of those loads.

If you were to see the swing 'down the line', you would observe this
phenomenon appearing as 'shaft droop', the shaft appearing to bow
outward away from the golfer while the toe of the clubhead droops. To
the extent that this CG alignment is a result of on speed, slower swings
will not create as much toe droop and forward bending of the shaft as a
Tiger Woods swing of around 125 mph. Obviously if the shaft is more
flexible the result is that it requires less speed / centripetal force
to align the CG.

I'm not a trained physicist so I apologize for the layman's explanation.

>
> You can note that the shaft flexes again after impact, and
> the clubhead again lags the hands.

Post-impact, this is also normal. The clubhead is slowed due to
collision with the ball. As the hands and arms decelerate, the clubhead
again passes the hands.

>
> Very poor club design. Tiger needs a substantially less
> stiff shaft so the thing kicks at the right time.
>
> I have no idea if that driver is one he uses regularly or was
> just present for his photo shoot, but the camera use by NIKE
> does allow a very nice capturing of shaft flex through a
> golf swing.
>
> -PA
>

http://clubmaker-online.com/bj01.html shows some pics of Bobby Jones
taken with high speed cameras. The same observations -- forward bend
and clubhead lead -- can be made there.

--
Ron

Date: 02 Oct 2006 15:11:58
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

The saga continues...Nike says
---------------------
We appreciate your detailed feedback regarding Tiger's shaft selection.
Please keep in mind, that Tiger is the one who selected the Diamana 83
for his SQ driver. We do not have any say as to which shaft he uses
for his club. I would recommend that you pass along this feedback to
his website at www.tigerwoods.com.
---------------------
We'll see where that goes.

-PA

Date: 03 Oct 2006 07:40:45
From: S McFarlane
Subject: Re: Tiger Woods driver shaft is TOO stiff

<blakestah@gmail.com > wrote in message
news:1159827118.261326.161330@k70g2000cwa.googlegroups.com...
> The saga continues...Nike says
> ---------------------
> We appreciate your detailed feedback regarding Tiger's shaft selection.
> Please keep in mind, that Tiger is the one who selected the Diamana 83
> for his SQ driver. We do not have any say as to which shaft he uses
> for his club. I would recommend that you pass along this feedback to
> his website at www.tigerwoods.com.
> ---------------------
> We'll see where that goes.

Very interesting. I wish I'd seen that before blowing so much wind. I
wonder if it's true that Nike has no say whatsoever in the area of shaft
selection. I find that hard to believe.

Scott

Date: 02 Oct 2006 13:47:11
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

sugnaboris@gmail.com wrote:
> blakestah@gmail.com wrote:
> > gpsman wrote:
> > > blakestah@gmail.com wrote: <brevity snip>
> > >
> > > > I have no idea if that driver is one he uses regularly or was
> > > > just present for his photo shoot
> > >
> > > And yet you *seem* to have concluded his "driver shaft is TOO stiff"...
> >
> > The driver in the photographs in Tiger Woods hand, yes, that
> > one, has a shaft that is too stiff for reasons I've already
> > outlined - the kick occurs prematurely, and the shaft flex is
> > retreating the clubhead from the ball at impact.
>
> Was this the trend from 100 or so swings, or are you just guessing it
> from a single swing (for a photo shoot, apparently)? If it's the
> former, then it might be worth establishing whether it was his usual
> driver, as it would be close to having some relevant information
> content. If it's the latter, then you have a near random observation,
> so even if it was his usual club, I don't think that his support team
> of experts will be in a great rush to implement any changes.
>
> You could try writing to them, though, just in case. Let us know how
> you get on.

It is clearly visible in the link I posted .

It is from a special photo shoot to show off Tiger's swing and
the Nike driver.

As I said, it could be something other than the driver in his bag.

I wrote Nike about it and expect not to hear anything from anyone
who knows anything about golf clubs, but I am sure their
keting people will fill it with the usual BS.

This raises an interesting point, though. In that golf swing,
the clubhead on the downswing initially lags the hands. Then
it rebounds and passes the hands (something Wishon claimed
can never happen, btw), and then it starts to rebound rearward,
and reaches the "straight" point at impact, after which it
predictably lags the hands again. Obviously, one important
point is that the shaft is close to straight at impact. Various
sources have always keted matching shaft flex to driver
clubhead speed so that the shaft was straight at impact and
kicked through impact. But Tiger's shows a straight shaft
and a reverse kick.

I had always thought the clubhead should lag the hands from
shaft flex on the downswing, and should catch up and
straighten at impact.

In engineering terms, these would be either a one PI phase
shift or a two PI phase shift. In the one PI phase shift
the shaft is kicking through impact. In the two PI phase
shift the shaft is kicking in reverse through impact.

It could be, for all I know, that well-tuned pros all have
the same sort of shaft flex seen in Tiger's swing. As I pointed
out, you can only make these observations by using a high speed
still camera throughout a golf swing, the shaft flex is obscured
using normal video cameras.

-PA

Date: 03 Oct 2006 07:32:27
From: S McFarlane
Subject: Re: Tiger Woods driver shaft is TOO stiff

<blakestah@gmail.com > wrote in message
news:1159822031.605875.124490@m73g2000cwd.googlegroups.com...
> It is clearly visible in the link I posted .
>
> It is from a special photo shoot to show off Tiger's swing and
> the Nike driver.
>
> As I said, it could be something other than the driver in his bag.
>

If you feel you have detected an error in the fit of the shaft in the
picture to Tiger's swing, then you are safe to bet your bottom dollar that
it is not in his bag.

The theoretical discussion of shaft flex and it's impact on end results is
definitely an interesting one, but it has given way to good old fashioned
empiricism as all scientific discussions must. Tiger Woods has probably
spent hundreds of hours on very high-tech measurement hardware and 100's of
thousands of dollars worth of shaft-Nike driver head combinations readily
available for data collection. The people who hand him the clubs for
testing likely have doctorates from MIT or equivalent.

IMO, there is ~ 0% chance that his playing shafts deviate any more from the
perfect theoretical match to his swing than the full brunt of modern
technology can provide. If that's not the case, then someone should be
fired. Given the amount of money in play, I'd be shocked if there's a
problem with his shaft flex, not to mention the amount of ink that is used
to label his shafts.

Scott

Date: 02 Oct 2006 17:24:04
From: RB
Subject: Re: Tiger Woods driver shaft is TOO stiff

blakestah@gmail.com wrote:
> sugnaboris@gmail.com wrote:
>> blakestah@gmail.com wrote:
>>> gpsman wrote:
>>>> blakestah@gmail.com wrote: <brevity snip>
>>>>
>>>>> I have no idea if that driver is one he uses regularly or was
>>>>> just present for his photo shoot
>>>> And yet you *seem* to have concluded his "driver shaft is TOO stiff"...
>>> The driver in the photographs in Tiger Woods hand, yes, that
>>> one, has a shaft that is too stiff for reasons I've already
>>> outlined - the kick occurs prematurely, and the shaft flex is
>>> retreating the clubhead from the ball at impact.
>> Was this the trend from 100 or so swings, or are you just guessing it
>> from a single swing (for a photo shoot, apparently)? If it's the
>> former, then it might be worth establishing whether it was his usual
>> driver, as it would be close to having some relevant information
>> content. If it's the latter, then you have a near random observation,
>> so even if it was his usual club, I don't think that his support team
>> of experts will be in a great rush to implement any changes.
>>
>> You could try writing to them, though, just in case. Let us know how
>> you get on.
>
> It is clearly visible in the link I posted .
>
> It is from a special photo shoot to show off Tiger's swing and
> the Nike driver.
>
> As I said, it could be something other than the driver in his bag.
>
> I wrote Nike about it and expect not to hear anything from anyone
> who knows anything about golf clubs, but I am sure their
> keting people will fill it with the usual BS.
>
> This raises an interesting point, though. In that golf swing,
> the clubhead on the downswing initially lags the hands. Then
> it rebounds and passes the hands (something Wishon claimed
> can never happen, btw),

I think that Wishon said 'clubhead lag' never happens jusr prior to
impact. Harrison (maker of shafts ) claims it does happen. However I
don't ever recall seeing a picture of anyone (not an Iron-Byron type
machine) lagging a clubhead behind a shaft pre-impact.

Clubhead *lead* is normal just prior to impact. Clubhead lag isn't.

> and then it starts to rebound rearward,
> and reaches the "straight" point at impact, after which it
> predictably lags the hands again. Obviously, one important
> point is that the shaft is close to straight at impact. Various
> sources have always keted matching shaft flex to driver
> clubhead speed so that the shaft was straight at impact and
> kicked through impact. But Tiger's shows a straight shaft
> and a reverse kick.
>
> I had always thought the clubhead should lag the hands from
> shaft flex on the downswing, and should catch up and
> straighten at impact.
>
> In engineering terms, these would be either a one PI phase
> shift or a two PI phase shift. In the one PI phase shift
> the shaft is kicking through impact. In the two PI phase
> shift the shaft is kicking in reverse through impact.
>
> It could be, for all I know, that well-tuned pros all have
> the same sort of shaft flex seen in Tiger's swing. As I pointed
> out, you can only make these observations by using a high speed
> still camera throughout a golf swing, the shaft flex is obscured
> using normal video cameras.
>
> -PA
>

--
Ron

Date: 02 Oct 2006 18:52:46
From: David Geesaman
Subject: Re: Tiger Woods driver shaft is TOO stiff

RB wrote:
>>
>> This raises an interesting point, though. In that golf swing,
>> the clubhead on the downswing initially lags the hands. Then
>> it rebounds and passes the hands (something Wishon claimed
>> can never happen, btw),
>
> I think that Wishon said 'clubhead lag' never happens jusr prior to
> impact. Harrison (maker of shafts ) claims it does happen. However I
> don't ever recall seeing a picture of anyone (not an Iron-Byron type
> machine) lagging a clubhead behind a shaft pre-impact.
>
> Clubhead *lead* is normal just prior to impact. Clubhead lag isn't.

I would love to see that camera turned on one of my very worst
block/slice swings. Maybe it's all simply the clubface being left open,
but I sure as heck feel like the clubhead is way behind.

As for the subject at hand, I think RB hit the nail on the head in that
this is a normal thing that we don't usually see in such graphical detail.

Further, to try and determine if the shaft is too flexible or too stiff
seems like a big stretch. Nobody's swing is perfect, and nobody says
that Tiger had any say in which swing was used for the sequence (he
could have trapped his hands a little bit and pulled a little bit of a
hook). It does illustrate though how much the timing of the release
must synchronize with the release of the shaft.

Dave

Date: 02 Oct 2006 12:11:23
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

blakestah@gmail.com wrote:
> gpsman wrote:
> > blakestah@gmail.com wrote: <brevity snip>
> >
> > > I have no idea if that driver is one he uses regularly or was
> > > just present for his photo shoot
> >
> > And yet you *seem* to have concluded his "driver shaft is TOO stiff"...
>
> The driver in the photographs in Tiger Woods hand, yes, that
> one, has a shaft that is too stiff for reasons I've already
> outlined - the kick occurs prematurely, and the shaft flex is
> retreating the clubhead from the ball at impact.

Was this the trend from 100 or so swings, or are you just guessing it
from a single swing (for a photo shoot, apparently)? If it's the
former, then it might be worth establishing whether it was his usual
driver, as it would be close to having some relevant information
content. If it's the latter, then you have a near random observation,
so even if it was his usual club, I don't think that his support team
of experts will be in a great rush to implement any changes.

You could try writing to them, though, just in case. Let us know how
you get on.

Date: 02 Oct 2006 11:00:14
From: Larry Bud
Subject: Re: Tiger Woods driver shaft is TOO stiff

> People think it is less kick if the shaft is stiffer, but in reality it
> mostly makes the club kick earlier and earlier. If they made
> a similar video of Tiger using a regular stiffness shaft, you
> would see more clubhead lag on the downswing, and the club
> would not return to straight before impact, it would instead
> lag through impact, and he would slice everything.

You've got it backward. Too stiff and you hit low cuts, too flexible
and you hit high hooks.

Date: 02 Oct 2006 10:54:20
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

gpsman wrote:
> blakestah@gmail.com wrote: <brevity snip>
>
> > I have no idea if that driver is one he uses regularly or was
> > just present for his photo shoot
>
> And yet you *seem* to have concluded his "driver shaft is TOO stiff"...

The driver in the photographs in Tiger Woods hand, yes, that
one, has a shaft that is too stiff for reasons I've already
outlined - the kick occurs prematurely, and the shaft flex is
retreating the clubhead from the ball at impact.

-PA

Date: 02 Oct 2006 10:43:50
From: gpsman
Subject: Re: Tiger Woods driver shaft is TOO stiff

blakestah@gmail.com wrote: <brevity snip >

> I have no idea if that driver is one he uses regularly or was
> just present for his photo shoot

And yet you *seem* to have concluded his "driver shaft is TOO stiff"...
-----

- gpsman

Date: 02 Oct 2006 08:55:36
From:
Subject: Re: Tiger Woods driver shaft is TOO stiff

Dave Lee wrote:
> <blakestah@gmail.com> wrote in message

> For most golf swings if you want the clubhead to have less of a tendency to
> be 'kicked forward' at impact, you would use a stiffer shaft.

The increased stiffness will make the club kick earlier.

People tend to think that in the limit they really want the club to
stay
as straight as possible.

But the image of Woods swinging makes it clear that the shaft bends
a LOT, even an ultra stiff shaft swung by Woods.

You have the option of making a much heavier shaft, or of
tuning the oscillation so that the club is nearly straight at
impact. In Woods case, the club oscillates back, forward, and
is midway towards oscillating back again when Woods
hits impact.

Ideally, you want it to oscillate back, and then forward at impact.
Kick at the right time.

People think it is less kick if the shaft is stiffer, but in reality it
mostly makes the club kick earlier and earlier. If they made
a similar video of Tiger using a regular stiffness shaft, you
would see more clubhead lag on the downswing, and the club
would not return to straight before impact, it would instead
lag through impact, and he would slice everything. If Tiger
decreased shaft stiffness just a little, he would hook everything.
If he decreased it more, the club kick would be just right, and
he would hit it 20-30 yards further. He has all the tools necessary
at his disposal to match his swing speed to the resonant
frequency of the club.

-PA

Date: 02 Oct 2006 23:09:00
From: Dave Lee
Subject: Re: Tiger Woods driver shaft is TOO stiff

<blakestah@gmail.com > wrote in message
news:1159804536.384764.5510@b28g2000cwb.googlegroups.com...
>
> Dave Lee wrote:
> > <blakestah@gmail.com> wrote in message
>
> > For most golf swings if you want the clubhead to have less of a tendency
to
> > be 'kicked forward' at impact, you would use a stiffer shaft.
>
> The increased stiffness will make the club kick earlier.
>
> People tend to think that in the limit they really want the club to
> stay
> as straight as possible.
>
> But the image of Woods swinging makes it clear that the shaft bends
> a LOT, even an ultra stiff shaft swung by Woods.
>
> You have the option of making a much heavier shaft, or of
> tuning the oscillation so that the club is nearly straight at
> impact. In Woods case, the club oscillates back, forward, and
> is midway towards oscillating back again when Woods
> hits impact.
> snip

I've looked at the video, but only on my laptop. I just don't see what you
are seeing - maybe on a better monitor??

But I don't see how it can happen. A typical professional golf swing
downswing takes around 200 to 250 msec (source Cochran/Stobbs "Search for
the Perfect Golf Swing"). A typical X flex 45" driver shaft would have a
natural frequency of around 290 cpm (period of around 200 msec). I just
don't see how it could go back, forth, and halfway back again (more than a
full oscillation cycle) on the downswing.

dave

Date: 03 Oct 2006 03:28:42
From: Kenny Stultz
Subject: Re: Tiger Woods driver shaft is TOO stiff

In article <g_gUg.9255$UG4.1321@newsread2.news.pas.earthlink.net >,
DaveLeeNC@ix.netcom.RemovE.com says...
>
>
><blakestah@gmail.com> wrote in message
>news:1159804536.384764.5510@b28g2000cwb.googlegroups.com...
>>
>> Dave Lee wrote:
>> > <blakestah@gmail.com> wrote in message
>>
>> > For most golf swings if you want the clubhead to have less of a tendency
>to
>> > be 'kicked forward' at impact, you would use a stiffer shaft.
>>
>> The increased stiffness will make the club kick earlier.
>>
>> People tend to think that in the limit they really want the club to
>> stay
>> as straight as possible.
>>
>> But the image of Woods swinging makes it clear that the shaft bends
>> a LOT, even an ultra stiff shaft swung by Woods.
>>
>> You have the option of making a much heavier shaft, or of
>> tuning the oscillation so that the club is nearly straight at
>> impact. In Woods case, the club oscillates back, forward, and
>> is midway towards oscillating back again when Woods
>> hits impact.
>> snip
>
>I've looked at the video, but only on my laptop. I just don't see what you
>are seeing - maybe on a better monitor??
>
>But I don't see how it can happen. A typical professional golf swing
>downswing takes around 200 to 250 msec (source Cochran/Stobbs "Search for
>the Perfect Golf Swing"). A typical X flex 45" driver shaft would have a
>natural frequency of around 290 cpm (period of around 200 msec). I just
>don't see how it could go back, forth, and halfway back again (more than a
>full oscillation cycle) on the downswing.
>
>dave
>
>

I can't see much on this video either as to how the shaft bends either. My
understanding is that, starting with the downswing, the shaft bends,
straightens out about when the shaft get horizontal, and then is bent
forward at impact.

Be careful about hanging too much on that 290 cpm. That's the frequency
measurement you get for an ungripped club clamped tightly in a vise. That
same club's frequency with a grip installed and held by soft (by comparison to
the clamp) human hands is a whole lot lower than 290 cpm.

Kenny

--
Kenny Stultz - Troll and SPAM intolerant
"Golf is the only sport where a precise knowledge of the Rules can
earn one a reputation for bad sportsmanship"

Date: 03 Oct 2006 12:59:26
From: Dave Lee
Subject: Re: Tiger Woods driver shaft is TOO stiff

"Kenny Stultz" <kstultz@comcast.net > wrote in message
news:4oe3naFe6g1tU1@individual.net...
> In article <g_gUg.9255$UG4.1321@newsread2.news.pas.earthlink.net>,
> DaveLeeNC@ix.netcom.RemovE.com says...
> >
> >
> ><blakestah@gmail.com> wrote in message
> >news:1159804536.384764.5510@b28g2000cwb.googlegroups.com...
> >>
> >> Dave Lee wrote:
> >> > <blakestah@gmail.com> wrote in message
> >>
> >> > For most golf swings if you want the clubhead to have less of a
tendency
> >to
> >> > be 'kicked forward' at impact, you would use a stiffer shaft.
> >>
> >> The increased stiffness will make the club kick earlier.
> >>
> >> People tend to think that in the limit they really want the club to
> >> stay
> >> as straight as possible.
> >>
> >> But the image of Woods swinging makes it clear that the shaft bends
> >> a LOT, even an ultra stiff shaft swung by Woods.
> >>
> >> You have the option of making a much heavier shaft, or of
> >> tuning the oscillation so that the club is nearly straight at
> >> impact. In Woods case, the club oscillates back, forward, and
> >> is midway towards oscillating back again when Woods
> >> hits impact.
> >> snip
> >
> >I've looked at the video, but only on my laptop. I just don't see what
you
> >are seeing - maybe on a better monitor??
> >
> >But I don't see how it can happen. A typical professional golf swing
> >downswing takes around 200 to 250 msec (source Cochran/Stobbs "Search for
> >the Perfect Golf Swing"). A typical X flex 45" driver shaft would have a
> >natural frequency of around 290 cpm (period of around 200 msec). I just
> >don't see how it could go back, forth, and halfway back again (more than
a
> >full oscillation cycle) on the downswing.
> >
> >dave
> >
> >
>
> I can't see much on this video either as to how the shaft bends either.
My
> understanding is that, starting with the downswing, the shaft bends,
> straightens out about when the shaft get horizontal, and then is bent
> forward at impact.
>
> Be careful about hanging too much on that 290 cpm. That's the frequency
> measurement you get for an ungripped club clamped tightly in a vise. That
> same club's frequency with a grip installed and held by soft (by
comparison to
> the clamp) human hands is a whole lot lower than 290 cpm.
>
> Kenny
>
> --
>

Yep - and the shaft is under significant load for a good portion of the
downswing further reducing the available time to recover.

dave

Date: 02 Oct 2006 12:48:36
From: John van der Pflum
Subject: Re: Tiger Woods driver shaft is TOO stiff

On 2 Oct 2006 08:55:36 -0700, blakestah@gmail.com wrote:

>
>Dave Lee wrote:
>> <blakestah@gmail.com> wrote in message
>
>> For most golf swings if you want the clubhead to have less of a tendency to
>> be 'kicked forward' at impact, you would use a stiffer shaft.
>
>The increased stiffness will make the club kick earlier.
>
>People tend to think that in the limit they really want the club to
>stay
>as straight as possible.
>
>But the image of Woods swinging makes it clear that the shaft bends
>a LOT, even an ultra stiff shaft swung by Woods.
>
>You have the option of making a much heavier shaft, or of
>tuning the oscillation so that the club is nearly straight at
>impact. In Woods case, the club oscillates back, forward, and
>is midway towards oscillating back again when Woods
>hits impact.
>
>Ideally, you want it to oscillate back, and then forward at impact.
>Kick at the right time.
>
>People think it is less kick if the shaft is stiffer, but in reality it
>mostly makes the club kick earlier and earlier. If they made
>a similar video of Tiger using a regular stiffness shaft, you
>would see more clubhead lag on the downswing, and the club
>would not return to straight before impact, it would instead
>lag through impact, and he would slice everything. If Tiger
>decreased shaft stiffness just a little, he would hook everything.
>If he decreased it more, the club kick would be just right, and
>he would hit it 20-30 yards further. He has all the tools necessary
>at his disposal to match his swing speed to the resonant
>frequency of the club.
>
>-PA

Maybe he's just biding his time until the rest of the tour catches up
with him again. Then --BOOM!!-- another 30 yards and he's back
intimidating them again.
--

jvdp
Myke Plough-in-skee is not mentioned in this thread.
http://www.rsgcincinnati.com/files/OH_2006_make_a_putt.avi
http://www.rsgcincinnati.com

Date: 02 Oct 2006 15:48:42
From: Dave Lee
Subject: Re: Tiger Woods driver shaft is TOO stiff