correct me if I am wrong... (like that won't happen. It's like I'm married to every one of you! If I don't comment am I still wrong?)

But, when I was lifting weights, the heavier the weight, the more we would "bulk up." That's the last thing I need to do at my age and weight.
You obtain better fitness with a faster cadence, right? Heck yes, I power down the hill in the highest gear I can, Then I focus on counting pedal strokes up the hill. I am getting up to 30 revolutions before I have to downshift to keep my cadence. Yes, I am standing off the saddle, can see the handlebars bending and snorting violently, but I do my best to keep my cadence. That's how I do my interval training. I down shift after my "count" and am cresting some of those hills that were kicking my big rhino tail and zoom ZOOM down the other side. (Remember a rhino's zoom zoom may not keep up with those cheetahs)