The bike shop sent me a a model TX 71 and it has an adapter claw attached. The off set on the claw (distance from the center of the axle slot and the center of the derailleur attachment)hole is about 54 mm compared to an adapter claw I ordered for a TX 50 Derailleur (27mm offset). If this will work OK I will keep it otherwise I will return it. Your advive would be appreciated.