A rotor (24; 224) for a Wankel engine comprising: two axially spaced apart end faces having a triangular profile with outwardly arched sides and three circumferentially spaced apex portions; a peripheral face extending between the end faces and defining three flanks, each flank extending between two of the apex portions, each flank having: a recess portion defining a recess with respect to the corresponding one of the arched sides to form part of a combustion chamber, the recess portion extending from a leading end to a trailing end of the recess, a leading portion extending along the corresponding one of the arched sides from one of the apex portions to the recess portion at the leading end, and a trailing portion extending along the corresponding one of the arched sides from the recess portion at the trailing end to another one of the apex portions; a bearing support extending between the end faces to support a rotor bearing, the bearing support having a central axis corresponding to a central axis of the rotor (24; 224); and a plurality of ribs (74, 76; 274, 276) extending between the end faces from the bearing support to each one of the flanks, the plurality of ribs (74, 76; 274, 276) including, for each flank, a first rib (74; 274) closest to the one of the apex portions and a second rib (76; 276) closest to the other one of the apex portions; characterised in that: the first rib (74; 274) is connected to the flank directly to the junction between the leading and recess portions and the second rib (76; 276) is connected to the flank directly to the junction between the recess and trailing portions. two axially spaced apart end faces having a triangular profile with outwardly arched sides and three circumferentially spaced apex portions; a peripheral face extending between the end faces and defining three flanks, each flank extending between two of the apex portions, each flank having: a recess portion defining a recess with respect to the corresponding one of the arched sides to form part of a combustion chamber, the recess portion extending from a leading end to a trailing end of the recess, a leading portion extending along the corresponding one of the arched sides from one of the apex portions to the recess portion at the leading end, and a trailing portion extending along the corresponding one of the arched sides from the recess portion at the trailing end to another one of the apex portions; a recess portion defining a recess with respect to the corresponding one of the arched sides to form part of a combustion chamber, the recess portion extending from a leading end to a trailing end of the recess, a leading portion extending along the corresponding one of the arched sides from one of the apex portions to the recess portion at the leading end, and a trailing portion extending along the corresponding one of the arched sides from the recess portion at the trailing end to another one of the apex portions; a bearing support extending between the end faces to support a rotor bearing, the bearing support having a central axis corresponding to a central axis of the rotor (24; 224); and a plurality of ribs (74, 76; 274, 276) extending between the end faces from the bearing support to each one of the flanks, the plurality of ribs (74, 76; 274, 276) including, for each flank, a first rib (74; 274) closest to the one of the apex portions and a second rib (76; 276) closest to the other one of the apex portions; characterised in that: the first rib (74; 274) is connected to the flank directly to the junction between the leading and recess portions and the second rib (76; 276) is connected to the flank directly to the junction between the recess and trailing portions.