Originally Posted by corners
Hmm, I've been looking at some older Yonex frames lately. Read a lot of reviews about the RDS 002 Tour, which looks very nice on paper, but quite a few posters described it as erratic on groundies. I wonder if it shared the 001 MP's torsional instability. Recently I've been leaning toward thinking that frame stiffness is relatively unimportant, in any plane. Maybe I'm wrong. Yonex certainly seems to be beefing up their beams, across their entire line, and from tip to butt.
Beam thickness is an interesting spec. Because of the RDC Stiffness Scale, where almost 99% of all frames on the market fall in the seemingly narrow range of 60-70, we tend to forget that the stiffness of a beam is is proportional to the cube of the beam thickness.
This means that a 25-mm beam racquet is over 3 times as stiff as a 17-mm beam racquet (given similar construction)!
Torsional stability is largely a function of beam width. Thus, a thicker beam gives a significant advantage in torsional stability. It's one reason that stiffer frames tend to offer better directional accuracy. But the thicker beam also comes at a cost of lower spin potential - this is the reason why widebody frames never caught on with higher level players until the advent of the modern spin-friendly stringjob. But with modern strings, if high performance is the goal, then there is no reason to use a flexible frame anymore.
With racquets targeted toward higher level players, we're seeing a homogenation of specs these days. Just about every frame has a stiffness rating in the high 60s now. And almost all of these have beam width in the 20-23mm range.
I don't see the 15mm-beam Donnay frames becoming a long-term seller. The one time I was hitting against a 4.0 player wielding a stock Donnay Gold, it was almost comical watching him try to return my hard heavy topsin serve - he couldn't figure out why the ball would hit his strings and rebound high in the air and toward the court to his left every time. Once I gave him one of my racquets, he was able to get my serve in play.