A hub clutch device for a bicycle includes a threaded shaft, a hub, a
positioning sleeve, a movable sleeve, an elastic member, a fixing seat,
and a plurality of urging balls. Thus, each of the urging balls is moved
between a respective one of the adjusting slots of the movable sleeve and
a respective one of the adjusting slots of the fixing seat to detach the
fixing seat and the movable sleeve from the positioning sleeve, so that
when the positioning sleeve and the hub are rotated, the fixing seat is
not rotated, so that the freewheel will not be rotated by the wheel when
the pedal stops operating.