A flexible surgical stapler includes an adapter having a coupling assembly configured for securing the adapter assembly to a handle assembly, an elongate body extending from the coupling assembly, a first drive assembly extending through the elongate body, and a loading unit secured to a distal portion of the elongate body. The loading unit includes a firing assembly operably connected to the first drive assembly. The firing assembly includes a cycloid gear assembly for increasing an input torque from the first drive assembly to actuate the firing assembly. The flexible surgical stapler may include an introducer assembly to facilitate introduction of a stapling portion of the surgical stapler into a body cavity of a patient.
