Originally Posted by hjacobson

By center to center I measured where the axis of each tube intersects the axis of the adjacent tube so, to within 1/8":
Seat tube from center of crankset to intersection with axis of top tube = 22-1/2" (tube extends up a further 5/8" or so)
Top tube from intersection with axis of seat tube to intersection with axis of head tube = 22-3/8"
Down tube from center of crankset to intersection with axis of head tube = 24-3/4"

Schwinn designated this a 23" frame.