I had similiar feelings initially about spinning, but lately have noticed a change. It comes from experience riding and an increased base fitness--from training for an riding full and metric centuries. There is probably a name for the phenomenon. It seemed that as I have reached a certain level of ability/fitness, my spinning has become more effective. One day I thought, "oh, so THIS is spinning!" Not feeling that it was ineffective, but like it was actually working. I was riding against a headwind the other evening and it really worked. I was also playing with riding way down in the drops and spinning, and it was so fun!