Not flaming, but I wouldn't say "women aren't into that." I love learning how to work on my own bike and am intensely curious about how it functions. I'm in a bike overhaul class at my local co-op right now. Of the ten students, six are women. I would say that girls don't usually get as much positive reinforcement to be curious about mechanical stuff as boys do, but that's changing. And there are a fair number of us who ride for a few years and then start getting curious about how the bike works. One challenge is that it's hard to find a place to learn how to wrench on your own bike. Bike shops are often dismissive of women customers (don't get me started on this one) and co-ops can have a really intense "dude culture" unless someone is being very intentional about creating a welcoming environment for everyone.

Back to the topic of the thread: Here in Memphis I would say that about 30% of the riders I see on my commute are women. The city has gotten much, much more bike friendly in the past few years so I expect to see that number improve over the next year or two.