Every Tues/Thursday nights I attend our local cycling class put on by a USALevel1 cycling coach. We even have our own Yoga instructor for 30 min's before we actually get on our bikes. We also alternate on nights doing 30 minutes core work.
Tuesday nights cycling usually involves some pretty high cadence work and then on Thursdays it's usually long intervals with rest and then some fast spinning towards the end of our hour.
It shells me..it's a great workout and I am loving every minute of it.
Sundays we do this for two hours..looking forward to the sweat fest on Sunday!