I forgot about the Equipe, which would indeed have used a 27.2mm post by virtue of its Columbus SL seat tube.

However, I am surprised at the range of posts used on the Tange frames. Normally, I would attribute this to a heavy handed person at the seat tube honing/reaming operation. However, I see that the 1984 Turbo was spec'd with a 27.2mm and the 1984 CompTA with a 27.0mm. To me this is unfathomable. Both Tange #1 and Tange #2 use the exact same seat tube. To carry it further, Tange #3 and even the plain gauge Tange #5 have the same wall thickness as #1/#2, at the top of the seat tube. This afforded the manufacturer the cost effectiveness of stocking only one post for a wide variety of frames.

The theoretical inner diameter for these Tange tubes is 26.8mm. After a light reaming/honing operation to clean-up the inside, most other brands using these Tange tubesets install a 26.8mm post. I could see a manufacturer opting for a slightly heavier removal, particularly if they regularly experienced distortion but to have two distinct sizes is puzzling. Besides losing the volume cost reduction from one size of post, there is the added cost of two distinct set-ups and the possibility of production and assembly errors. Very strange.