I have a Legnano 531 Olympiad??frame with the seat bolt in front of the seat tube.?that I purchaed from the Big Wheel bike shop on Holly St.Denver in the 70s? Serial#1600R can anyone help with putting a date to this? My son Paul thinks it was late 1970s anyhelp anyone. Thanks and Cheers John Crump OldsnowedinBrit. Parker, Co USA