The calculation of the instationary loaded bearings of crankshafts presumes knowledge of the bearing forces. The standard methods for the calculation of the main bearing forces for multiple (that is, statically indeterminate) supported crankshafts are based on considerably simplified assumptions. Thus the results of the calculations are not representative of actual working forces. The new, improved method presented here considers the crankshaft as a straight beam on plain bearings. With this system the forces and dislocations of all bearings influence each other, since the distribution of the operational forces over the individual bearings depends on the crankshaft deformation and therefore on the position of each journal within the bearing. Therefore the forces and dislocations are matched to each other by iteration. A comparison of calculation results with measurements shows a substantial improvement over the methods commonly used.