When I had my red racer, it had a Specialized Milano saddle. It was comfortable. On my new bike, a Klein Navigator, I use the same saddle in the same spot, and it hurts. Both bikes were fitted to me identically by the LBS.
Why was the Milano comfortable on one bike and not on the other. I firmly believe that saddle height, front-aft tilt, and horizintal positioning are identical on both bikes. In fact, the same stem is used on both bikes and the top-tube lengths must also be identical based on my measurements & confirmation from the LBS.
If I put my Fizik Dolomiti on the new bike, it's better, but only for the first hour (after which my sit bones are sore & bruised).
Suggestions and speculations, please? Thanks!