A bicycle crank assembly having a rotational center axis is basically provided with a crank member and a sprocket member. The crank member includes a support portion that extends in the axial direction and an arm portion that is integrally rotatable around the rotational center axis with the support portion. The sprocket member includes a sliding portion that extends in the axial direction that is integrally rotatable with respect to the support portion and that is displaceable in the axial direction. The bicycle crank assembly is constructed to achieve high strength and to suppress the decrease in the efficiency of the rotation transmission from the crank member to the sprocket member in a crank assembly in which the sprocket member is movable in the axial direction.