The present invention refers to a conventlonal spur gear transmission or magnetic gear transmission, With a cycloidal configuration. The magnetic gears include contact points such that the mobile gear rolls on the fixed gear. Alternatively, a balance wheel is incorporated, which generates a centrifugal force opposite to the one associated with the mobile gear, of equal magnitude and on the same plane as this latter one, thereby completely eliminating the unbalancing of the mechanism. The balance wheel is mounted on the high-speed shaft in a manner similar to the mobile gear, and has the freedom to displace itself radially through centrifugal effect in the opposite direction to the eccentric position of the center of the mobile gear until it presses against a fixed track over which it rolls, concentric with the fixed gear with an equal force, opposite and collinear with that produced by the mobile gear.