Originally Posted by
CV-6
27.0 would imply a 753 frame. The Trek 753 frames (170) did not have eyelets.
I'm thinking you meant that 27.4mm would indicate a frame with 753 seat tube(?).
If a 27.2mm seatpost or two don't fit in the frame then it is sized smaller than 27.2mm.
I have at least one example of just about about every size of seatpost on hand, so always use a post as a guage.
I have in a couple of instances used a particular one-size-larger post in a frame whose printed specifications and supplied post both were a smaller size.