The coefficient of friction (CoF) between the deflection pulley and rope in a lift strongly affects the life span of the rope. Although surface roughness is a key factor affecting the metallic pulley–rope CoF, its effect on polymeric pulleys is unknown. The present study analyses the effect of roughness and working conditions on cast polyamide 6 (PA6G) deflection pulley–thermoplastic polyurethane (TPU)-coated rope contacts. The statistical analysis revealed that the effect of surface roughness on the CoF for low-load tests was significant. The present study contributes significantly to parameter selection in deflection pulley machining to minimise friction between the pulley and rope.