Some saddles require a different setback then others. I bought a light touring bike and put a Brooks saddle on it. Could not get the saddle back far enough (knee pain is an indicator for me). Brooks saddles don't slide back as much as others due to all of that laceing they put underneath. Changed the "radial" post out for a 2 bolt model with extended setback and life is good. I tend to ride smaller frames as my legs are long and torso is shorter and compressed due to age. So, I need a post/saddle combination that allows for me to adust fit.

BTW, whats up with those radial posts? Really couldn't stand the one that came on my Salsa Casserole. The whole saddle tilt versus setback was much too finicky for me.