I tried to join my school's weight training class. It was an extra cirricular that would've replaced my gym credit so I was all for it and the trainer Miss Anders was thrilled. But the boys essentially laughed me out and I didn't try to go back. I went into karate instead, and that was a blast. Good luck with your biking!
I did one in school, and there were some girls on it, and they got along fine, even the ones who didn't really want to lift. But you have to be careful with those classes, because the teacher can really mess you up. Mine had us bench everyday, which is fine if your volume is 200 lb total. But my friends and I would be doing five sets of eight with a plate, and it lead to shoulder problems for me.
I'm not totally upset with it, though. It was a little school (~300 students 6-12) in a really small hick town. I enjoyed karate much more than weights anyways.