Every morning as we walk the kids to school I see lots of people riding bicycles to work. Although Paris is not a bike-friendly city like, say, Amsterdam or Copenhagen, as far as I can tell Parisian drivers seem to respect bicyclists.
The vast majority don't bother with helmets either, regardless of age or gender. Riding without a helmet is common in Europe and it seems that pushing helmets makes city bike programs unsuccessful because it promotes a sense of danger that maybe isn’t justified. I'm sure for Parisians it's also due to appearance and that people are not as obsessed with safety.
Also interesting is the number of female motorcyclists there are in Paris, of which I caught a few while shooting bicycles.