the Champion should be accompanied with a number: Champion #1...#2, #whatever. The number indicates the lightness of the frameset, with #1 being lightest, I believe. The material was very good quality, seamless steel tubing that was alloyed with chrome and molybdenum, thus the cromo indication. Reynolds 531 was an alloy containing manganese and molybdenum...I think that this alloy was supposed to yield a higher tensile strength. In practice a rider probably would not notice the difference. It's a good bike...