Would you folks say that, even though NYC, LA, Portland, etc... have a large number of female racers, their per-capita representation is the same or greater than other cities?
One hypothesis could be that LA has a large number of female racers by virtue of LA simply having more cyclists in general.
That was the cool thing about living in SF, whatever small niche activity that you are into, you can still find a group to do it with. e.g. if you are into longboard skateboarding, you can find a crew in SF, but not so much in Montgomery, AL.