In this video of a lower level spin class, Nick Perna discusses the “sweet spot” or the “slippery spot” for spinning.  He explains exactly how to find this spot on the blade for fast, long-lasting, and quiet spins.  (If you watch the skaters, not too many of them really seem to have found it, but they’re trying.)

Unfortunately the microphones aren't very sensitive so we can’t "hear the silence" that Nick is talking about.  Watch the spins carefully to see what part of the blade they’re using.  This was a fun class for the skaters.