Yeah, by ear. I never know or look either. The only thing I always try to remember is to make sure that if I'm going to shift out of the middle ring, that I'm vaguely in the middle in back, so that I don't crosschain, which would be SO annoying. Otherwise, I do everything by feel.
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks