measuring your sit bones

[lph]

(mine are 170-190mm, and my hips themselves are not very wide. Sit bone width and hip width don't have much to do with each other)

Just wanted to ditto this - there really is very little correlation. I have narrow hips but quite wide sitbones. Yesterday I saw a rare pic of me biking taken from behind and it was actually visible, both the wide "seating" and the thigh bone that seemingly goes straight down.