OK, went out and measured the OD of the seat tube and got 1.127" = 28.62mm

The wall thickness is supposedly .9mm, so .9 x 2 = 1.8mm

28.62 - 1.8 = 26.82mm for tubing ID


I also tried my hand at measuring the ID with the calipers in several points around the opening and came up with an average of 1.057" = 26.85mm


So, both methods agree that the correct seatpost is 26.8mm.

Problem solved. Now to find a decent seatpost! Any suggestions???