Drivetrains and frames for vehicles, equipment, machines, etc. Some embodiments of the drivetrains and frames are particularly suited for human powered machines, such as bicycles and exercise equipment. In some embodiments, a drivetrain includes a reciprocating crank coupled to a crank pivot. A lever couples to the crank via a lever pivot positioned on the crank. A lever stop cooperates with a lever guide surface to guide a motion of the lever as the lever pivots about the lever pivot. The lever and/or the crank are operably coupled to a drive pulley, idler pulley, and/or compound pulley. In some embodiments, a drive cable operably couples the lever and/or the crank to the drive pulley, idler pulley, and/or the compound pulley. In one embodiment, one or more pulleys couple to the lever's distal ends. In some embodiments, the drivetrain includes a wheel hub adapted to receive torque from the crank via a drive pulley.