Any way to measure a seatpost diameter without using the cool jig/tool the bike shop 5 miles away has. Thinking back to high school math class and if I know the diameter....or use a small piece do string or...I know is is not 27.2 and it is an Italian frame, the Saronni we discussed last week, it arrived and I'm bolting up a Campy Record 9 group

but the seat posts I have are all 27.2's. I think it is a 26.8....thanks guys