Originally Posted by travlerajm
The two racquets have the same swingweight when measured in the plane normal to the stringbed, but if you mounted them in an RDC machine with the handle rotated 90 degrees to measure the swingweight in the plane of the stringbed, the racquet with higher twistweight would measure higher swingweight than the other because the added weight on the sides of the hoop is farther from the pivot point than if the weight were placed in the center of the stringbed.
Your actual swing occurs in a plane that is neither completely normal nor completely parallel to the stringbed, so the twistweight contributes to the "effective" swingweight, which is always slightly higher than the measured swingweight. In most cases, the difference between measured swingweight and "effective" swingweight is consistent enough that it is not worth worrying about the difference. But the example presented (with 2 frames of equal mass, balance, and measured SW, but different mass distributions) is a case where the difference does come into play.
I have to go catch a plane this morning, so I'll leave a drawing to someone else.
sure, I get all of that. But you never said before that 'I' in your MgR/I equation is (as you call it) 'effective swingweight'. And if it is - than aren't all your line of thinking based on observed correlation between ATP player's racket specs and MgR/I of those rackets kind of baseless? Since I'm pretty sure that all data about player's rackets refers to what commonly is known as 'swingweight' and not 'effective swingweight'?
Also, isn't saying "In most cases, the difference between measured swingweight and "effective" swingweight is consistent enough that it is not worth worrying about the difference." a bit misleading? As you pointed out yourself - if you add weight to the sides of the racket the 'effective swingweight' actually changes apparently noticeably. Isn't adding weight to the sides of the racket like at least as common as adding the weight at the top or bottom of the racket? In other words 'most cases' is like 50% of the cases, no?