Cycling in Cologne
Cologne is flat, so it's easy to get around by bike and the sights along the Rhine River are gorgeous, and easily accessible from the seat of a bicycle.
Rhine River bike path.
Attractions/sights accessible by bicycle from the city centre:
Palaces of Brühl (15km), City of Düsseldorf (40km) or Bonn (30km).
Mayor's stance on cycling:
They are slowly improving the infrastructure for cyclists.
No problem if you have a good lock!
Cycling at night:
Most streets in my city are well lit