A bicycle crank assembly adapted to be rotatably supported by a bottom bracket in a hanger tube for rotation about a central rotational axis (A) of the bottom bracket , the bicycle crank assembly comprising: a first sprocket including a plurality of first teeth and at least one first mounting portion having a first mounting opening ; a second sprocket including a plurality of second teeth and at least one second mounting portion having a second mounting opening ; a crank arm including at least one sprocket attachment portion having a third mounting opening ; a plurality of sprocket fixing structures securing the first and second sprockets to the crank arm via the first, second and third mounting openings; and a plurality of alignment tubes non-detachably fixed to or integrally formed with one of the first sprocket , the second sprocket and the crank arm , characterized in that the alignment tubes are extending through corresponding ones of the first, second and third mounting openings such that the crank arm and the first and second sprockets are aligned by the alignment tubes and are dimensioned relative to the first, second and third mounting openings such that the first sprocket and the second sprocket are accurately positioned relative to the crank arm and the center rotational axis (A), wherein each of the sprocket fixing structure includes a fixing nut having an internal thread and a fixing bolt having an external thread, the external thread of the fixing bolt being threaded into the internal thread of the fixing nut, the fixing nut being embedded in a resin part of the first sprocket, wherein the fixing nut includes an abutment part that contacts one of the first and second sprockets , while the fixing bolt includes an abutment part that contacts the other of the first and second sprockets , and wherein the alignment tubes are integrally formed with the fixing nuts respectively and extend axially from the abutment part . a first sprocket including a plurality of first teeth and at least one first mounting portion having a first mounting opening ; a second sprocket including a plurality of second teeth and at least one second mounting portion having a second mounting opening ; a crank arm including at least one sprocket attachment portion having a third mounting opening ; a plurality of sprocket fixing structures securing the first and second sprockets to the crank arm via the first, second and third mounting openings; and a plurality of alignment tubes non-detachably fixed to or integrally formed with one of the first sprocket , the second sprocket and the crank arm , characterized in that the alignment tubes are extending through corresponding ones of the first, second and third mounting openings such that the crank arm and the first and second sprockets are aligned by the alignment tubes and are dimensioned relative to the first, second and third mounting openings such that the first sprocket and the second sprocket are accurately positioned relative to the crank arm and the center rotational axis (A), wherein each of the sprocket fixing structure includes a fixing nut having an internal thread and a fixing bolt having an external thread, the external thread of the fixing bolt being threaded into the internal thread of the fixing nut, the fixing nut being embedded in a resin part of the first sprocket, <EOS>