Originally Posted by Grasschopper
When you sit on the Specialized pad they have you sit on it on a chair and then raise your feet onto a box (or similar). This number is NOT the width of the saddle you should get. They take this info and then cross reference it to their chart which takes into account your riding position, a deeper aero position yields a thinner saddle recomendation, more upright is wider.
I did this and got their Avatar saddle in 143mm width and it has been great. Even before I got that saddle I knew the suggestion was going to be pretty close because I had been on a 133mm Selle Italia SLK which hurt and my commuter has a WTB Speed V which is 147mm and is super comfortable for me. I say get a Specialized fitting done (takes 5 min and is free) and then use that info to get your next saddle, be it Specialized or other.
On the Specialized site, they have a chart showing what seat width "fits" the range of sit bone measurements, and takes into account riding position (upright vs. aero). I also looked for dealers with the BG system and there is nothing close (nearest is 220 mi. away) so I'm hoping that info isn't accurate and my LBS can help me.