Hi, JR~
This may be shameless self-promotion, but I've teaching spinning for 6 years. I
now teach Tuesday mornings and evenings at Harbor Fitness in Park Slope (6:30
AM, 7PM). These classes are geared towards the moderate to serious athlete, as
I, too, want to get in good cross training while I do the job. You can just pay
the guest fee if you come, which I think is $10. You might also talk to the
manager and see if you can work out a deal. Ya never know.
Let me know if you have questions.

The number and location are at the site below:
http://www.harborfitness.com/intro/
~Colleen