The realization of a train of molecule-gears working under the tip of a scanning tunneling microscope (STM) requires a stable anchor of each molecule to the metal surface. Such anchor can be promoted by a radical state of the molecule induced by a dissociation reaction. Our results, rationalized by density functional theory calculations, reveal that such open radical state at the cyclopentadiene core of star-shaped pentaphenylcyclopentadiene (PPCP) favors the anchoring. Furthermore, to allow the transmission of motion by STM manipulation, the molecule-gear should be equipped with specific groups facilitating the tip-molecule interactions. In our case, a tert-butyl group positioned at one tooth end of the gear benefits both the tipinduced manipulation and the monitoring of rotation. With this optimized molecular system we achieve reproducible and stepwise rotations of the single gears and transmit rotations up to three interlocked units.