A chain tensioning device includes a main body, a chain guide and a rotary fluid damper unit. The chain guide is pivotally coupled to the main body to rotate around a rotational axis with respect to the main body. The rotary fluid damper unit is operatively connected between the main body and the chain guide to provide rotational resistance to the chain guide around the rotational axis. The rotary fluid damper unit includes at least one primary flow limiting valve and at least one support member. The primary flexible valve portion of the at least one primary flow limiting valve is configured to flex and contact the at least one support member to form a primary flow path between a free end of the primary flexible valve portion of the at least one primary flow limiting valve and the other of the first and second members.