I read somewhere, maybe on this forum, that you can put a piece of aluminum foil on carpeted steps, sit on foil with legs out and get a pretty good indent of sit bones. I did so, with a towel since our stairs are wood. Measured three times, got the same measurement and then did it at LBS on pad. VERY SAME. IT WORKED. There is some great advice here, I have been dialing mine in for over a week and have it where it is really working well. Just takes patience and a good hex wrench!