Bikes are allowed on most trains, except those highlighted in the BART schedules. It is the rider's responsibility to refer to BART schedules. Regardless of any other rule, bikes are never allowed on crowded cars.
For stations that don't have wide fare gates, use a regular fare gate to process your ticket and then use the manual swing gate, usually located next to the attendant booth, to move your bike to or from the paid area.
Bikes are allowed in any car but the first car of a train. There are no bike racks on board. Hold your bike while on the trains.
During morning and evening commute hours bikes are not allowed in the 12th and 19th Street Oakland Stations (as indicated in the BART schedule.)