Awesome bike rental system, a great way to see the city on the cheap. Montreal is a hugely bike-friendly city so you will find bike paths everywhere. C$5/day lets you take out a bike for 30 minutes at a time. Return it to any dock, walk around for a couple of minutes, and take out another one and repeat. You aren't going to win the Tour de France on these bikes but they're good enough to get around the city and you can't beat the price. Be aware that the charges start racking up from 31+ minutes. They definitely want you to put the bikes back quickly so someone else can use them.
Download the Bixi app to your phone, which will tell you not only where the docks are, but also how many bikes and empty spots are available. Very clever system. The bikes close up shop during the winter. Check the website for months of operation.
The bike rental shops must be going out of business. Our group of 3 rented Bixis all day for C$15 total.