I know cycling classes generally speaking are extremely intense. Being an extremely high cardio workout, will this mainly make you lose fat, or will it bulk up your legs as well??? I know some people consider them to go hand in hand, but I was curious if anyone has been through many cycling classes.

 

Depends on the class.

Most of the spinning classes are just cardio, without strength so you will not get any more bulk in the legs.
I use the CTS videos myself as they will workout different aspects of your routine.
Low RPM/high resistance for strength.
High RPM/Low resistance for speed and some High RPM/high resistance for strength at speed