How much does RA decrease over time?

[IowaGuy]

Does anyone have any data as to how much the RA (stiffness/flex) of a racket decreases with time?

Let's say a Prostaff starts out at 65 RA. How much (if any) would this decrease over 5, 10, 20, 50, 100 stringjobs? (assuming stringing puts the most stress on a frame, and contributes to the eventual weakening of the frame)

 

[Slicerman]

My Blade started with a measured 65 RA brand new. I think after about 6 stringings over 6 months, the re-measured stiffness rating was 63 RA.

 

[esgee48]

There is no set pattern. It depends on how hard the ball flexes the frame and frequency/tension of string jobs. The epoxy matrix that binds the graphite sheets starts to break down/develop micro cracks with ball impacts. The hoop also does this every time you do a string job. Being player specific, a pro can break down a frame in 12 months or less. A low level non improving player will basically be using a brand new frame for decades.