[BerntR]

Hello Yoda,

I learned tonns about the golf stroke from the time before this site was launched. The flying wedges and the separation between swinging and hitting cleared up my head.

But I still think there are unclarities in TGM with regards to some of the mechanics involved. And the part that has some relationship to golf shafts have always struck me as odd.

I am wondering whether HK simply forgot to regard the club itself as an energy storage device. You can load it with energy, and it will release the energy when the moment it is subjected to is reduced under a certain threshold. Whether the energy is wasted or well spent is a question that is very similar of nature to the compression leak issue.

The shaft bending and release kind of works in the same way as a capacitor in an electric curcuit - you deliberately charge it, and it uncharges itself when the voltage is reduced below a certain threshold. And the centripetal force - the pure rotation - well - it stores energy pretty much the same way as an inductor. It will do it's best to keep the current constant.

(Modeling the golf mechanics as an electrical circuit could prove to be an interesting exercise, but perhaps not in this thread):

Thanks for your post, BerntR. Once again, I want to respond to this very important point.

1. The Clubshaft has inertia. Tipped-stiff or senior flexible, it has inertia.

2. At the same time, Centrifugal Force has a Line of Pull. That invisible line is from the #3 Pressure Point (first joint of the right forefinger) to the Sweetspot. This is what is driving the Club, not the Clubshaft.

I agree with what you're saying, but "rope pulling" isn't the only source of shaft bending. And probably not the largest either. If this was the case, we could all pick shafts on basis of swing speed alone.

I believe you are talking about the phenomen I described under the pure rope handling :

And then some people are using an almost pure rope handling technique throughout without any of these shaft loading bursts. In addition to the extensive shaft loading we see above, the rope is pulling the center of gravity. And since this isn't on the shaft axis it will cause shaft bend as well. In which case the mechanical properties of the shaft will have less influence on distance, but perhaps on direction.

Well - I should have replaced COG with COI, but I hope you can see through that

For an Iron the centripetal force will flatten the lie angle of the club - pretty much as we see in your picture. ANd of course this isn't something we will se upfront at impact. And for a driver with COG well behind the sweeetspot it will also bend the shaft forward.

But since this kind of shaft bending is a function of the centripetal force - and that will pretty much be intact until impact - the shaft will not straighten or whip back midway. I sustain that a lot of players is applying a vicious newtonian moment with their hands on the shaft. So in many swings there are two sources of shaft bending. Actually three if you also consider the collision with the ball. If you apply your right hand #PP's and have the right hand below the left on the shaft - it is in a way - something that can't be avoided.

3. The inertia of the clubshaft cannot keep up with the Centrifugal Line of Pull. Hence, it lags behind.

I'm not sure if I understand what you're saying here. Are you talking about inertia as in mass times distance squared?

Since the COG of the clubhead isn't in the extension of the shaft, the (virtual) rope is actually bent to begin with. The centripetal force will try to pull the rope to it's full length. And the shaft bends such that the distance between the hands and the COG of the clubhead increases.

This 'reverse' parabola (reverse in that the forward bend is counter-intuitive) made a dramatic appearance in Ben Hogan's first book,[i] Power Golf.

I think we need to separate forward bend (because moment was applied to the grip end earlier and the shaft has kicked forward later) and downward bend caused by centripetal force + a COG offset in the clubhead. At 7-8 o'clock the two may be hard to separate on a face-to-face picture. The bend in picture 2 I commented seems way too eccessive to just be due to a COG pulling action though.

And there's absolutely no doubt whatsoever that picture 1 has a shaft bend that works agains the bending you will see from a pure rope pulling technique.

Like it or not; Some of the top ball strikers are bruteforcing the club to swing - at least in parts of their stroke.

But Zuback seems to be quite moderate in this department though. Maybe it is because he only has a moderate wrist cock at the top and in his early downswing. So I guess anyone who is willing to settle for around 200 MPH ball speed doesn't load the shaft in the early downswing