以SHIMANO XT SHADOW來說~ 原廠給的資訊: SHIMANO XT SHADOW RD-M772 SGS RD-M772-SGS Series DEORE XT Shifting Action Top Normal SHADOW Mount Type Drop-out Maximum Sprocket 34T Minimum Sprocket 11T Front Difference 22T maximum Total Capacity 45T Capacity : GS 33T, SGS 45T