Planning a four night stay in Berlin with my two adult children. We want to bicycle in the countryside outside of the city during the day, and enjoy the city in the evenings. Any recommendations for areas, hotels, bicycle rentals, bicycle guides, scenic routes/trails? One day we want to ride to Potsdam for sure.
I recommend to choose hotel close to a regional train station e. g. Alexanderplatz, Friedrichstraße, Zoologischer Garten or Hauptbahnhof (main station) to have easy and time-reducing access to regional trains. In August the 9 Euro ticket for each person is your cost-saving alternative for all 4 days inclusive but be aware on special rules of local transport for taking bikes on board.
For your Brandenburg (Berlin surrounding) plans you better try to find a bike rental which provides tour/trekking bikes, not city bikes only. These are more likely connected to a bike shop or are specialised tourist bike rentals (e. g. Berlin bike rental).
Last tip: as long as you are in Berlin be aware of bicycle thieves.
Thank you, Mark, for your suggestions!