Originally Posted by
FBinNY
Typo?
30.0 - 27.2 = 2.8 / 2 = 1.4mm wall. Pretty thick for a steel frame.
In any case most quality 27.2 ID steel seat tubes are 28.6mm OD (1-1/8") with a 0.7mm wall.
If it's aluminum, the likely OD would be 31.75mm (31.8)
No typo.
My Bare Knuckle's seat tube OD is 30mm at the top and tapers down very slightly to about 29.8mm below the external butting. My wife's Soma Rush is the same, as are the Pake Rum Runner and All-City Big Block. And yes, I just measured all four frames.
Edit for the record: The MASH Work, Affinity LoPro and Surly Steamroller take a 30.0 collar too. Go figure...