You get a bike for 15 $ a day (first day). Each following is 10 $ a day. For a week you pay 50 $. 50 $ deposit required. You can choose between Cruisers and Mountainbikes. Only one gear - but really okay.

Just in case that you can't get Bixi-bikes (because those damn machines don't accept your credit-card), Ça Roule is a good alternative. If you take an old bike 24 hours are 25 $ (without tax). Every following day is 6 $. You get locks, a repair-kit and helmets (if you want). You should get your bikes there if you want to go up the Mont Royal. It takes you a while and the 21 gears make it easier.