Rick Steves recommends bike tours:
For a quick but meaningful spin around town, consider a bicycle tour. You’ll find fun and memorable guided bike tours in Amsterdam, Barcelona, Berlin, Bruges, Budapest, Munich, and Paris, as well as many bike-friendly countryside areas. You’ll get a young, entertaining, often foul-mouthed, sometimes informative guide who will give you a breezy introduction to the city and a close-up look at back streets few tourists ever see. Tours are typically fun, reasonable (roughly $30), and an easy way to meet other travelers as well as get a new angle on an old city.