Where are they getting the 30,000 rpm figure from?
As they found it took a seriously powerful router to get that speed over 25,000 rpm! The spindle motor on a CD drive is not nearly as powerful. Even though the insides of the drive are better optimized from an aerodynamic standpoint, the amount of electrical power required would be far greater than a small PM motor that's used.
If you do the math, reading a cd at single speed on the innermost tracks at 550 rpm would require > 30,000 rpm to achieve the rated speed. But there's a catch. CD's are recorded in a way that one must vary the speed to maintain the same data speed. (CLV) The newer drives (started after 8X) were CAV which meant they were capped on the innermost tracks and would only achieve the absolute max rating on the outermost tracks.
The same is true today with 48X units. Most start out around 16X speed on the inner tracks. This is roughly 8800 rpm. Still very fast but a far cry less than 30,000! The fastest drives begin at 24X (around 13,000 rpm max) which is less than half the seemingly critical mass speed of 30k.
