Originally Posted by icemilkcoffee

All I know is- the nicer drop bars from that 90's to early 2000's period were all 26.0mm. ie. the lightweight T6 hardened drop bars were almost all 26mm, the carbon fiber drop bars were 26mm (and didn't grip well enough at that diameter), and most of the drop bars that had compound 'anatomic' type curves were also 26mm.
The road quill stems with detachable faceplates tended to be the 2 bolt varieties for some reasons. And these had a tendency to rock when you're pulling hard on the bars. I had a Deda style 2 bolt at one point, and it was rocking like crazy on climbs. The hinged stems did work well for this purpose, but I think single bolt stems were still the norm all the way through the end of the quill stem era.