Originally Posted by
mshred
pretty easy to measure your sit bones at home. i put a folded up towel on a wooden chair (coffee table might work too) and put foil over it. sat down on the foil and my sit bones leave a nice indentation. measure the distance in mm between the indentations and you've got your sit bone measurement. i did it 3 times and took an average just to be sure i didnt screw it up the first time.
Realizing of course that distance between sit bones doesn't always correlate to saddle size. The shape of the saddle has a lot to do with it as well. If one fits a 143 Toupe, a 143 Romin will be too narrow. The 155 will more likely fit better. The size Specialized quotes is edge to edge at the widest point, not the support points.