Is there a rule of thumb for determining seatpost diameter for frames based on vintage, country of origin, etc? I've seen frames of similar vintage (mid 80s) with different seatpost diameters. Basso - 27.2; Merckx - 27.0; Pinarello - 27.0. I was trying to determine seatpost size for a Torpado frame that is probably of a similar vintage, but the 27.0 seemed too big. Are there any rules that make determining seatpost diameter for frames easier?
Thanks in advance.