Houston, we may have a problem...

From some of the comments here I think you folks are measuring, um, a little too far back. The portion of your bones (ischial tuberosity ?) that constitute your sit bones (in the context of road cycling) are the portion that bear your weight when you are riding a road bike, not when you are sitting in a chair, not when you are riding some hybrid sitting straight up. Maybe your handle bars are seriously too high...

That means that if you are anywhere near sticking your hand up your butt in finding your sit bones you are too far back. Try again.