A bicycle drive unit includes a housing, crankshaft and a propulsion assist motor. The housing is configured to be mounted on a frame of a bicycle. The housing includes a first portion and a second portion. The crankshaft is provided to the first portion of the housing. The propulsion assist motor is provided to the second portion of the housing and configured to assist propulsion of the bicycle. The propulsion assist motor includes a rotational axis extending in a direction intersecting a direction in which the crankshaft extends. The second portion has a maximum dimension of smaller than or equal to 75 mm in a direction orthogonal to the rotational axis of the propulsion assist motor.