A bicycle rear sprocket assembly comprises a plurality of sprockets and a sprocket carrier. The sprocket carrier includes at least ten internal spline teeth and a circumferentially extending non-splined portion. The at least ten internal spline teeth extend in an axial direction with respect to a rotational center axis of the bicycle rear sprocket assembly. The at least ten internal spline teeth includes a plurality of internal-spline driving surfaces. The plurality of internal-spline driving surfaces each includes a radially outermost edge, a radially innermost edge, and a radial length. The total of the radial lengths ranges from 11 mm to 14 mm. The circumferentially extending non-splined portion is disposed to be adjacent to the at least ten internal spline teeth in the axial direction and recessed from the at least ten internal spline teeth in a radial direction with respect to the rotational center axis.