Originally Posted by pvaudio
This is not a general rule. Federer does this, every 6 games I believe. Venus Williams has on many occasions played with a single racquet per match when winning. This was when she played full gut, and now when playing a poly hybrid.
There is already a thread on this topic actually. For a high swing speed, poly will return more energy into the ball in the form of spin than Kevlar. As I mentioned in that thread, Agassi who used Kevlar for many many years said something to the effect that they need to let everyone know about poly or get rid of it because it produces so much spin per stroke. Sampras, upon trying it in retirement, said that it was like cheating due to the shots he could hit. Jim Courier at first didn't like poly BECAUSE it produced too much spin and he couldn't hit flat enough.
Regardless, if you feel Kevlar produces more spin, then use Kevlar. The likely reason you are getting the impression of greater spin is because Kevlar lets you swing as hard as you want at the ball, more or less. Poly, on the other hand, has more power, but greater elasticity, so if you have a less spin-generating stroke, then your impression will be that Kevlar is better for spin. I'm not going to argue why an entire industry has shifted if you personally like the spin of Kevlar.
Okay but kinda funny the way you say fed changes often and then go to serena and a bunch of players from the 90's. Do you not watch modern tennis? Almost all the top male players change their rackets with every ball change.
Again agassi talking about poly has little to do with amateur players because we do not use a fresh string job every half hour. I like poly better than anything for the first hour or so, but it changes a lot after that. So ya if i had at new string job to use as often as I wanted to poly would be unbeatable.