Dear MelanieC - get thee to a spin class!!! If you're just pedaling your spin bike, you're missing the boat and the party. And you're actually not utilizing the equipment in the way it was designed to be used. The only way to explain it is: ask around, find a good class, and most gyms will let you pay $10 or whatever to try out a single session. Hills, slow climbs, jumps, runs - other than the warm up, there is no "just pedaling." You generally leave soaking wet, so don't plan anything immediately afterward without a shower! Enjoy.