Originally Posted by Anton
Interesting theory, but even without questioning methodology there is clearly a problem:
stiffness of a racket is not tested in stringbed plane, it is tested in normal to stringbed plane ONLY.
From your examples - Super spiny K 6.1 95 has flex rating of 69!
From your earlier comments one would draw conclusion that because k 6.1 95 is stiff, then therefore it is not as spin friendly as something similar specs but softer, for example Yonex RQiS 1 Tour, which is btw has quite low rebound angle (and I assume spin)
So is the problem that only data on the stiffness in the plane normal/perpendicular to the stringbed - as the RDC machine measures - is publicly available, and not stiffness in the plane of the stringbed?
Travlerajm corrected himself up-thread - it was the N6.1 (65 RDC), not the K6.1 (69 RDC), that he found relatively stiff in the plane of the stringbed compared to its stiffness in the plane perpendicular to the stringbed (65 RDC).