Re: ShopTalk: FUJIKURA PRO VISTA 60

[John Kaufman]

Hi Dave, Some years ago I took Dynacraft's course titled something like Advanced Shaft Technology. There was quite a dicussion about their DSFI emperical fitting equation. I remember one of the terms in the equation was the fifth root of torque. The fifth root of any small number such as a typical torque value is a number slightly larger than one. I thought it was a rather insignificant term but I had a calculator with me so just for the  fun of it I cranked in a few numbers. A one degree change in torque changed the desired frequency by 10cpm. That surprised the hell out me and I'm not sure I really beleive it. It almost sounds like if we switch from a typical graphite (4 degrees or so) to a typical steel shaft we'd be down near lady's flex. Cheers, John K ----- Original Message ----- From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, October 03, 2003 1:48 AM Subject: Re: ShopTalk: FUJIKURA PRO VISTA 60 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