Now to your question. The shaft is a torsional spring between your hands and the club head. The stiffer the spring (the lower the 'torque' value) the more compliant the club head is to the motion of your hands, in other words the more closely the club head will follow the motion of your hands, or the less 'lag' there will be between the club head and your hand movement (just like with shaft longitudinal stiffness). The resistance to twisting comes from the moment of inertia of the club head about the twisting axis (the hosel axis in simplest terms). This is why large club heads are more difficult to 'close' than smaller ones, they have a larger MOI about the hosel axis (they also have a larger MOI about their own center of gravity, which makes them more 'forgiving').
When your customer said that a higher torque shaft makes it easier to draw the ball, I suspect he was thinking "A higher torsional stiffness shaft makes it easier to draw the ball.", which is probably true, there is less lag between the closing of the hands and the closing of the club face making it more likely that the club face will be slightly closed at impact.
'Torque' is the rotational 'force' that the hands apply to the butt of the shaft, the club head moment of inertia about the twisting axis is what resists that 'torque', and the shaft is what connects the two. The torsionally stiffer the shaft (the connection) the more tightly connected the hands and club head are. 'Torque Value' is the number we assign to indicated the torsional stiffness of a shaft, which, unfortunately (especially since people seem incligned to shorten this to simply 'torque'), is inversely proportional to torsional stiffness, which is what we really should be talking about.
How's that for confusing?
Alan
At 02:48 AM 10/3/2003 -0400, you wrote:
In a message dated 10/2/2003 6:52:22 AM Pacific Daylight Time, [EMAIL PROTECTED] writes:
At 07:05 AM 10/2/03 -0400, [EMAIL PROTECTED] wrote:
>...the torque in relationship to relative stiffness or frequency is a
>fitting variable that is often overlooked when fitting a shaft to an
>individual. If we are talking frequency which only tells you half a story,
>a 250 cpm shaft @ 2 degrees of torque will feel and perform different than
>a 250 cpm shaft @ 5 degrees of torque. Tom Wishon had a chart that had a
>relationship between swing speed torque and frequency with adjustments for
>frequency to torque relation a very useful tool for adjustments.
Charlie,
I don't remember ever seeing this curve -- explicitly anyway. Where did you
see it?
That is not to say that Tom didn't implicitly give us all the info for the
curve. In fact, he has published the info at least twice that I know of.
* In 1991, he and Jeff Summitt co-authored the book "Modern Guide to
Shaft Fitting". If you plot their DSFI formula, it relates frequency to
torque for the same subjective "stiffness".
* In 1996, Tom's "Modern Clubfitting" book has a table of RSSR numbers
that can be similarly plotted.
When you plot both of them, you can see that he felt torque was less of a
factor in 1996 than he did in 1991. His view has been changing over time.
(That's not a bad thing. We live and learn. I certainly have learned a lot
about how golf clubs work in the last 5 years.)
Cheers!
DaveT
Hi Dave and all,
I had an interesting discussion with a customer tonight who correctly pointed out that a shaft does not have torque on account as it has no horsepower it merely has resistance to torque, on this we agreed, where we dis agreed was that he felt that a shaft with more torque would help him draw it more, and I felt that the more the torque the more the head would resist squaring, he claims to have data to support the opposite, this from a Dr Joe Corvi who is supposedly the Only guy who understands and can relate all of Einstein's theories
?
David
