How do you measure torso and arm lentgh for found the effective top tube. I have one groupset and wheels. Two of my road bikes one aluminum one is steel the aluminum is 58cm the top tube is 56cm. The steel bike is 56cm seat tube and 56cm top tube. I want upgrade one of that bikes and i try found what effective top tube is good for my height 5`7 feet and my inseam is 32"