A reciprocating piston combustion engine with at least one cylinder (2) in which a piston (1) is located, so it can be moved in a reciprocating manner; a first crankshaft (4); a second crankshaft (6); wherein the first crankshaft (4) and the second crankshaft (6) extend parallel to each other and rotate synchronously in opposite directions; wherein the rotation axes (X, X′) of the two crankshafts (4, 6) extend parallel to a common cylinder midplane (Z) and laterally offset relative to it; wherein a first piston rod and second piston rod (3, 5) are arranged at the reciprocating piston (1), so that the first piston rod (3) is pivotably connected to the to the reciprocating piston (1) with its first end and rotatably connected to a crankpin (40) of the first crankshaft (4), and that the second piston rod (5) is pivotably connected with its first end to the reciprocating piston (1), and rotatably connected to the crankpin (60) of the second crankshaft (6) with its second end, and wherein the crankshafts (4, 6) are engaged with each other through synchronizing gears (42, 62), is characterized in, that the two crankshafts (4, 6) are supported in at least one common bearing block (7; 107; 207); that the bearing block (7, 107, 207) is made of a material with a first thermal expansion coefficient, that the synchronizing gears (42, 62) are made of a material with a second thermal expansion coefficient, and that the dimensions in the radial direction of the bearing block (7; 107; 207) and of the synchronizing gears (42, 62), and the first and the second thermal expansion coefficients, are matched in such a manner, that the thermal expansion of the bearing block (7; 107; 207) occurring between the two rotation axes (X, X′) of the bearing block (7; 107; 207) is substantial equal to the thermal expansion of the synchronizing gears (42, 62).