Data point #5: my friend A. says she didn't bicycle. She then proceeded to tell me about the series of bicycles she owned, and details of a cycling history that included attempting to put a child's seat on the bike so she could bicycle with a <2 year old (it didn't work, but most attempts to put a child's car seat on a bike don't work). She could not remember, but didn't think she'd ever seen anyone else put a kid on a bike -- she just thought it was a logical thing to try.
She also went to Germany and came back inspired to try bicycling to run errands here in Mass, but gave it up because it was too uncomfortable in traffic.
I just wish I could find someone else -- anyone else -- who documented this. Because right now it's looking like a black hole for citational purposes. But a survey instrument, a video camera and a few trips to senior-housing would produce a gold mine.