It's true. I take part in the least heterosexual form of exercise on the planet. You sit on a static bike in a classful of others. To your front is a staggeringly fit instructor wearing a Britney-mic, yelling commands and encouragement as you pretend to climb hills and sprint along flat bits, using resistance on the bike's wheel, to the accompaniment of loud music. Sound a bit silly? It certainly is.
But then it's the best exercise I've ever done. I begin to match the dark red studio wall behind me within 5 mins and at the end of the session I'm saturated with sweat. A few other observations:
1) By god the music helps. Cheesy euro house does the job fine, but I always find a bit extra for that drum n'bass remix of Outer Spaced by The Prodigy.
2) It can chafe.
3) The Friday instructor, despite being about 5'3" is so fiercely fit (and in fact simply fierce) that she actually gets the back of the heavier-than-me bike to hop up when she accelerates.