Abstract: In a drive arrangement particularly for use with the chain drive of a cycle a rotatable mass or member, (3;13;19) is arranged to receive rotational drive from the chain (4). The rotatable mass or member is preferably statically and dynamically unbalanced by weight means (19) and is so driven in relation to the positions of the pedal cranks (5,6) during the rotation thereof by a rider of the cycle that impulses of force are imparted to the chain drive in such manner that the operational forces developed in the chain drive are augmented.