One reason I go to spin class is to get motivated by a great instructor with great music and who pushes me in a way I can't do on my own. Usually the music is new stuff that I would otherwise never hear. Even if most of it is dreck (unworthy garbage) I appreciate the sentiment, because it keeps me current with popular culture. But for whatever reason, there is a thought that new music is the only music that people want to hear in spin class and can't grind it out to anything else.
Spin instructors of the world: bring on the classic rock. Where are Pink Floyd, Aerosmith and Led Zeppelin among the your playlists? I'm not talking Stairway to Heaven, which is slow and drawn out, but tunes like Money, Rag Doll, and Kashmir could get my cadence to 130 just as well as any Jay-Z or Rihanna tune (not those artists produce garbage-like music; I actually like their stuff. It's the other dreck that I am talking about).
One instructor told me that jam band tunes are too long, and preferred spin songs are no more than 4 minutes. Check out this very rocking instrumental Frankenstein, originally by the Edgar Winter Group, and covered by my favorite band.
But if you think it is too jammy, just cut it short. No one would mind.