There are lots of places where is possible to rent a bicycle for a tour. This is especially nice on days where the weather is pleasant (if not we can suggest to take a Bus tour on Bus 100 and 200 that will take to some of the Touristic attractions). The cost is about 10 euros per day. Being Berlin quite a flat city, it is relatively easy to ride a bike. If you keep yourself in the bike path, your journey will be (relatively) safe.
It is also possible to go on an organised tour.
Bike TourKnaackstraße 97