A cylinder lock includes a latch retractor housing having inner and outer cover plates, inner and outer drive spindles extending respectively through the inner and outer cover plates, a sleeve surrounding the outer drive spindle and having a flange contacting the outer cover plate, an outer shell surrounding the inner drive spindle and the latch retractor housing, and at least one rigid coupling member or tube disposed within the outer shell and engaging and coupling together the inner and outer cover plates and the flange, thereby reinforcing the outer drive spindle and the latch retractor housing and increasing torsional and compression strengths thereof. A reinforcing ring is further provided to couple the outer drive spindle to the outer handle for reinforcement.