What they all said.

I also think that bike=machine=technical=male thing plays a role. So are cars, and women do drive, but cars are larger, messier and more expensive to repair, so not that many men spend time wrenching their own cars. But walk into a bike store and you'll find men happily discussing the minutiae of bike parts and how to wrench this or that. I guess women may feel that if they're not mechanically inclined, this isn't the sport for them. Skis are pretty straight forward, by comparison.