Fahrrad, Zweirad, Velo, Radl, Drahtesel. Germans love their bicycles. So much so that they have a complete repertoire of names for each part of one that you'll have a very hard time translating due to the multiple trivial names, none of which have anything to do with the English term. Makes for lots of fun when one tries to change a flat tire.
Going to any Hauptbahnhof (central train station) you will undoubtedly see a sea of bicycles somewhere where they allow parking for bikes. That is the best place to observe the huge popularity of this means of transportation in the country.
I was lucky enough to have one lent to me for the summer by a coworker, and let me tell you, the freedom of riding a bicycle in this country is amazing. Whatever stops automobiles is no obstacle für meine Fahrrad. Forest? No problem, there's paths through to anywhere you need to go. River? Oh look, a bicycle and pedestrian bridge, right over there! Autobahn? Kein problem, there's an overpass built there just for me. Oh how riding a bicycle simplifies life.
Unfortunately, the huge popularity of bicycles here makes them particularly attractive to thieves, even ones that one would consider not worth stealing.