Hello.

I was measured for a Specialized Body Geometry Saddle. The bike tech measured the width of my sitz bones (perch) as 125 mm. He then recommended a couple of models in the 155 mm width.

My question: Is this a standard method of sizing where one would take the measurement and then add 30 mm to the measurement?

When I first read about the Specialized Body Geometry Saddle fit, I imagined that the advertised saddle size would match the dimension of one's sitz bones. Turns out, the saddle size is actually the width of the saddle (maximum) but the sitz bones will positioned somewhere between the center groove in the saddle and the edge.

I have been riding narrower saddles but am looking to optimize my fit. Specialized saddles are available in narrower widths that are still wider than my perch so I am asking, what is the right factor to add to the bio measurement?

Thanks!