A bicycle drive unit comprises a housing configured to be mounted to a first base member. The housing includes a first wall at least partly defining an internal space to at least partly accommodate a bicycle crank having a crank rotational axis. The first wall includes a first transmitting surface disposed to at least partly face upward in a bicycle upright state where the crank rotational axis horizontally extends and the housing is mounted on the first base member. The first transmitting surface is configured to face a first receiving surface of the first base member to transmit an upward force from the housing to the first base member. The first transmitting surface being at least partly disposed below the crank rotational axis in the bicycle upright state.