Most of us know that fit which is always debated on the 41 is a riddle to many of us and even a work in progress for pros.
3 pts of contact on the bike and if you get is wrong, can lead to pain and discomfort. Get it right and it transforms the riding experience.
And of course some days we get it right better than others. To me saddle setback and pelvis position on the bike is key. Inadequate saddle setback and pelvis rotation translates to too much weight on the hands and really destroys comfort and power to the bike.
Even though the following article is a self promotion for SMP saddles, an insightful article about pelvis geometry worth a glance if you haven't seen it:
http://www.stevehoggbikefitting.com/...ll-about-smps/
Hogg is a prolific writer on bike fit and one of my favorites as he writes with great clarity. Probably the large majority of those who ride a road bike don't understand pelvis geometry included Mr. Hogg when starting out which was a refreshing admission for a bike fit expert which btw I believe him to be. Reality is a pelvis is a pretty complex structure and most of us who haven't been initiated wouldn't understand how it relates to a saddle on a bicycle. Saddle width is often equated to the distance between ischial tuberosities or what are generically referred to as sit bones. This is an inaccurate oversimplification however. The pelvis as it rotates forward in terms of saddle contact narrows dramatically. So choice of saddle is probably more of a function of your pelvis rotation or lack thereof than any genetic distance between your ischial tuberosities or so called sit bones.
So sitting armchair fashion on an Ass-O-meter isn't going to tell you what your best saddle width is going to be for riding. There are other soft tissue issues as well when it comes to saddle shape that Hogg mentioned as well.
Words are an inadequate substitute for a picture and the third, top view picture is the best picture I have seen which illustrates how the inferior ramus of the pelvis is the true contact to the saddle when in a proper pelvis tilted forward riding position which straightens the lumbar region of the back and promotes torso tilt conducive to minimizing air drag. Cobb also speaks frequently about this in his videos which I also find informative.