Biking in and around Bruges is a treat that was much loved by all of us. Pick up the biking brochure (BEF50/$1) from the travel information office on the Burg, which gives 5 bike routes of varying lengths and difficulty. There are several bike rental places around town. De Ketting is one of the farthest out and the least expensive (when you need to rent five, it makes a difference). However, Bruges is a small, easily walkable town and the walk was about 15 minutes from the town center. They had nice bikes available in sizes for all of us, with easily operable locks and laid-back terms. The shop closed at 6 pm, but we were told just to lock the bikes outside the shop if we returned later. Also, no deposit.
We biked both around town and out a popular 30-40 minute route canalside to Damme, another quaint mideival town, not nearly as touristed as Bruges. Biking is daily transportation in Bruges (and in much of Europe) as opposed to recreation or exercise as here in the U.S. This means the town and countryside are set up for biking with easily accessible and navigable bike lanes and paths. Also, and more importantly, local drivers are used to bikes - they will grant you the right-of-way. (In your turn, you must grant rights-of-way to pedestrians).
Biking in Bruges and the Belgian countryside was voted a favorite by all of us, ranging in age from 7 to 51. Fresh air, exercise, idyllic scenery, canals and windmills - who could ask for more?