It took me 4-5 months of being a spinner before I realized how to master the standing position. One day in my regular teacher's class, she cued it different. "Pelvic tilt" were the words that came out of her mouth. I thought "Ahhh!". Once you find the right pelvic position, you're golden.

Trying to think how to describe it. I guess it's the reverse concept of doing standing squats with weights. If you do a squat, you tuck your pelvis inward, or forward slightly to protect your lower back. On the bike standing, you slightly shift your pelvis weight back towards the saddle. It's a very sublte rotation of the pelvis girdle in a different center of gravity over the bike, vs thrusting your whole posture backwards. This takes some of the work weight off your quads, and engages the hip flexors and glutes more I feel. It's a matter of learning a different feel for balance. Just like the first time you rode you bike outside as a kid without the training wheels. At first, it had some crashes, and felt very awkward. Then, after a while, your body knew exactly what to do .

I love spinning so much. It is such a great activitiy. I was frustrated with learning the tehcniques for a while, but knew I enjoyed it on the whole right off the bat. And, btw, I did feel like I might die after my first class. Glad you are going back for another try!