I'd bet money that it's too pear-shaped and maybe even too wide. My sit bones are 120-125mm and I had similar issues with a SI Lady Gel Flow...it was both too wide and too pear-shaped for me (as well as too soft). I've been MUCH happier on a Specialized Jett 143, which is very T-shaped. I'm actually contemplating moving to the even firmer Ruby in the same size.