Magnetic cycloidal gear assemblies and mounting arrangements for magnetic cycloidal gear assemblies are provided that include a fixed stator and a cycloid that rotates eccentrically within the stator. The cycloid can be mounted to an offset cam on the input shaft by a rolling element bearing. A plurality of cam followers connect the cycloid to the output hub. Various features can be provided to increase operational balance or stability. For example, an adjustable counterweight can be attached to the input shaft. Also for example, a mounting arrangement including an adjustable nut, one or more bearings, and/or one or more wave springs can be provided to allow for the application, balancing, or adjustment of axial forces within the assembly.