D.C. is a fairly bike-friendly city. Except for the ire provoked by the sometimes reckless local bike messengers, cars and bicycles coexist peacefully. It's best to avoid the streets during rush hour, if possible.
Except for weekdays 7-10 AM and 4-7 PM, the Metro system allows riders to bring bicycles aboard any car of the train. Bicycles are not allowed on the Metro on days when large crowds are expected, such as July 4, though foldable bicycles are allowed at all times. The fronts of all Metro buses are equipped with racks that can hold as many as two bikes. The racks may be used for no additional charge throughout the day, including rush hour. Riders are responsible for securing and removing their own bikes.
Washington Area Bicyclists Association (202/628-2500. www.waba.org).