Violette, I gauge my workouts on a number of things, but it really comes down to how I'm feeling that day. My heart runs like a bunny and I have a heard time keeping my heartrate low (I've seen it as high as 220 during a hill climb). Assuming I feel good, I generally work at a pretty high intensity. I try to spend a minute here and there doing an active recovery though to get my heartrate back down, no matter what the instructor might otherwise be telling us to do. We don't have cadence monitors on our spin bikes, so that part of it is mostly by feel. If I am feeling tired or overworked, I may drop everything down a few notches and spend the majority of class just spinning a moderate resistance at a moderate rate.

On my bike, I tend to ride long and steady, although I plan on working some intervals into my training this year. I generally stay in a range of gears that allow me to comfortably spin at 90-100 rpm. My heartrate is usually about 75% of max, although that can jump up in a headwind.

My cadence on a hill really just depends on the hill. If it's short and steep, I may just get out of the saddle and power up it. If its longer, I try to find a gear where I can spin about 70-80 rpm. I read once that you should aim for a cadence during a climb that is 85% of your "normal," flatland cadence. That's just a guide though. With each hill, you ideally find the gear that allows you to utilize both your muscle strength and aerobic capacity, without burning out either one of them. That's different for each rider.