A bicycle drive unit is disclosed that includes a case frame, crank shaft,
front sprocket, rear hub shaft and rear sprocket. The crank shaft
includes first and second support portions that are spaced apart from one
another and are supported on opposite lateral sides of a forward portion
of the case frame. The first and second support portions are engaged with
bearings supported on opposite sides of the interior of the case frame.
The front sprocket is installed on the crank shaft within the case frame
and between the first and second support portions. The rear hub shaft
includes a third and fourth supporting portions that are spaced apart
from one another with the rear sprocket installed on the rear hub shaft
therebetween.