I was working in a Starbucks yesterday, located right on the most popular north-south bike route across the island on Rue de Brébeuf. From the corner of my eyes, I could see a continuous stream of bikes passing by, and when it was time for a break, I decided to do some counting. Starting at 4:01 pm, I counted bike traffic for 45 minutes. I tried also recording the (assumed) gender, whether people were riding a Bixi, and whether they were wearing a helmet or not. Despite it being the end of October, the weather was pretty nice—about 13 degrees and partly sunny. Bike traffic was definitely not at its rush hour peak yet, but I got a good sample size during the 45 minutes (and probably would have had a hard time keeping track of even more people biking past).
The gender split is fairly equal -- something definitely not true in many other places in North America. There were 44% women and 56% men (I didn't count kids separately). The split between helmeted and bareheaded people was almost exactly the same: 46% with, 54% without a helmet. Women were slightly more likely to wear helmets than men (52% versus 42%). Bixi riders made up 11% of the total bike traffic—and to my surprise there were 18% of them wearing a helmet!
data of the bike counter on Laurier (choose the monthly view), this leads to a severe cut to the number of people cycling.