Toronto is not a bicyclist's paradise; The drivers resent you and the bumps, potholes and patches shake your teeth out. On the other hand, it is relatively flat and dense, and if you are touring rather than commuting there are many nice, relatively safe ways to get around on a bike. Sites on Bikes was created by "Jake and Dan, two Torontonians and recent university graduates who saw a need for guided bicycle tourism in the downtown core." They are outfitted with new but retro Schwinn 5 Star Cruisers and are running tours all summer. They range from two to four hours (deluxe tours can be longer) and can be customized; there are food tours, bike and shop tours and "dinner and ride" tours.
On a bike, you see everything and can stop anywhere, carbon free and great exercise, just be sure to cross streetcar tracks at ninety degrees. What a wonderful idea at ::Sights on Bikes via ::Spacing Wire
Map of departure point here