Mike O - Ok, yes I think we're talking about the same thing - and you're right, clubmakers call it droop. I know nobody here gets Golf Digest, but the latest has a good picture of Camilo Villegas on the cover at impact from up the line that shows this. Put a straightedge on the handle and see how much the tip of the shaft has bent downward.

Also, your point on camera angle is well taken. However, I would say that if you could get an image with the head say 6 inches or so before impact the droop would be pretty much invisible (because it's directly perpendicular to the camera angle) to a camera viewing face-on and you'd be seeing the forward or backward bending predominantly. That's why the deflection curves generated by strain gauges that indicate the kind of shaft behavior I described are somewhat more convincing to me. Still, the images I have seen with that just by chance have clubhead very near the impact point have not shown a lagging clubhead - but you never know.:)

Anyways, I think I've kind of beat this subject to death, but while I'm somewhat clear on the difference your referring to with swinging and hitting (longitudinal vs radial), I don't think I understand why the centrifugal (centripetal) force of the clubhead on the shaft would be much different between the two. I'm probably missing the point here but from my college physics days, the centrifugal force would be equal to the clubhead mass times the clubhead speed squared all divided by the radius of the circular motion of the clubhead (at high clubhead speeds it turns out to be quite a large force). None of these factors would seem to be dependent on swinging or hitting given the same clubhead speed(maybe radius slightly?). Maybe TGM is using the term centrifugal force differently than the literal scientific meaning. I'll have to go look at the book again.

BTW, I'm not sure I've been very clear on this, but I wasn't suggesting that there was never clubhead lag in the swing - there certainly is and it is lagging for most of the downswing until the point the clubhead reaches a speed where the centrifugal force overwhelmes any pushing or pulling acceleration on the shaft and drives toward the center of gravity alignment we discussed. Maybe you're saying the same thing in your last paragraph before the PS? Good discussion.

This is an excellent summary and very important to understand for proper clubHEAD control.

Deeper and Deeper
 

[quote=jmessner]Mike O - Ok, yes I think we're talking about the same thing - and you're right, clubmakers call it droop. I know nobody here gets Golf Digest, but the latest has a good picture of Camilo Villegas on the cover at impact from up the line that shows this. Put a straightedge on the handle and see how much the tip of the shaft has bent downward.

Also, your point on camera angle is well taken. However, I would say that if you could get an image with the head say 6 inches or so before impact the droop would be pretty much invisible (because it's directly perpendicular to the camera angle) to a camera viewing face-on and you'd be seeing the forward or backward bending predominantly.
We're in agreement here- exactly my point- thanks for seeing it.

That's why the deflection curves generated by strain gauges that indicate the kind of shaft behavior I described are somewhat more convincing to me. Still, the images I have seen with that just by chance have clubhead very near the impact point have not shown a lagging clubhead - but you never know.:)
See my last comment in this section- I think it applies to your comment here.

Anyways, I think I've kind of beat this subject to death, but while I'm somewhat clear on the difference your referring to with swinging and hitting (longitudinal vs radial), I don't think I understand why the centrifugal (centripetal) force of the clubhead on the shaft would be much different between the two. I'm probably missing the point here but from my college physics days, the centrifugal force would be equal to the clubhead mass times the clubhead speed squared all divided by the radius of the circular motion of the clubhead (at high clubhead speeds it turns out to be quite a large force). None of these factors would seem to be dependent on swinging or hitting given the same clubhead speed(maybe radius slightly?). Maybe TGM is using the term centrifugal force differently than the literal scientific meaning. I'll have to go look at the book again. Good points- would love for you to post the formula with an example- only if you have the time and interest- Hey, there's other things in life to do! As far as your understanding of the clubshaft differences between hitting and swinging- I'm thinking that you aren't quite seeing the difference in regards to TGM- Let's cover it a little later in this thread when I have time.

BTW, I'm not sure I've been very clear on this, but I wasn't suggesting that there was never clubhead lag in the swing - there certainly is and it is lagging for most of the downswing until the point the clubhead reaches a speed where the centrifugal force overwhelmes any pushing or pulling acceleration on the shaft and drives toward the center of gravity alignment we discussed. Maybe you're saying the same thing in your last paragraph before the PS? Good discussion.

I was justing that it might be possible that if the sweet spot was far enough back from the shaft- that you might have a condition where the shaft would curve forward- but the sweetspot would be at or behind that line of pull or longitudinal center of gravity- thereby having lag looked at in relation to the sweetspot but appearing to have throwaway if looking at the clubshaft. That's making a big assumption that the center of gravity that was back of the shaft- would move in line with the shaft by moving forward - and not just close the clubface to get in line with the shaft- as Homer notes on page 82.[/QUOTE]

Notice my comments above, but I'm with you we've beat this horse enough that I've A) lost some interest and B) reached my limit of any significant understanding of the subject matter.

Damn Leo....where you'd get the "Old School" look...Man your your swing looks great!!!!:laughing9

Mike 0 - Just to tie off our discussion because I agree it has run its course - here's the formula and example:

Centripetal Force example
F=m(v^2)/r
m=mass of clubhead (200g for a typical driver)
v=velocity of clubhead (let's assume 100 mph @ impact)
r=radius of curvature of clubhead motion (shaft length is a good approximation, but it could be slightly longer, let's try 45")
Anyway, then F=79 pounds force for this impact condition. The force is considerably less at other points in the swing.

There's a table with similar calcs here plus more discussion on shaft bending.

The second paragraph I quoted I think you have it right. Yes the shaft could bend forward and the sweetspot still not be even with the shaft. In fact, according to some, having the CofG inline with the shaft is the maximum condition that can occur but is not always fully achieved. There is some twisting going on too but I have to assume that it's not the biggest effect - otherwise we'd all be hooking our large headed drivers off the planet and most people tend to have more trouble getting the larger heads around.

thanks
 

thanks- some very good points!

It seems as though the stiffer the shaft the less forward bend the shaft would have at impact with Swinging. If this is the case why wouldn't the Swinger always use the stiffest shaft possible to allow the Hinge Action control the club face more accurately?:question:

As already suggested, I'm no TGM expert on the differences between swinging and hitting but I can give you my view on shaft flex. In general, it takes a faster swingspeed to bend a stiffer shaft a given amount, and shaft bending significantly contributes to the feel of the shaft. So if the golfer can't really bend a shaft it feels harsh, like a pipe, and it might be harder to "feel" the head through your hands during the swing. For some golfers, the feel is important and if the feel isn't just right it throws them off. It also might be harder to square up the face somewhat with less bending and you'll also likely get a lower launch angle. The general rule of thumb is that you'll get a little more control with a stiffer shaft (assuming the golfer swings the same which is a big question if the feel is poor) but better trajectory (maybe distance too) and more solid feel with a more flexible shaft. It is recommended to always go with the more flexible shaft if there is any question.

Hopefully, some experts will weigh in on the application to swingers...

Good subject for a new thread
 

Shaft stiffness should be the subject of a new thread. One thread one subject. I'll start.