After emailing Citizen Bike, they kindly responded with some info on the Barcelona and the Miami:
Barcelona -the BARCELONA Citizen Bike has a rear Shimano Nexus 3-speed internal hub with a 14 tooth cog. The front chainwheel is a 32 tooth chainwheel with 152mm crank arms. The Shimano Nexus hub is a model SG-3R42.
The tires are Kenda Kwest 20 x 1.75 (65psi) tires in a custom cream color made exclusively for the BARCELONA.
Miami- The MIAMI Citizen Bike has a 6 speed Shimano derailleur with a rear freewheel that ranges between 14 - 28 T over six gears. The front chainwheel is 46T with 170mm crank arms
Although I don't know if I used it correctly, I calculated a gear ratio of 31 - 58 inches for the Barcelona, and 30-61 gear inches for the Miami. Please correct me if I used the gear formula at Sheldon Brown wrong.