It seems there are a variety of vintage Campy NR/SR seatposts that vary on diameter. Checking my own rolling inventories, I have 27.2, 25.4, and 26.8 diameters to name a few...
I have been surprised several times that the vintage frames that I have purchased require a different size seatpin than what I have available. Matching seatpin sizes can be difficult unless you have that vintage size readily available for immediate use. Measurements are sometimes misleading because the seat tube bracket is altered to remove the old seatpin.
Is there a internet cross list available that details what OEM frame models use specific size diameter seatpins? I know that French manufacturers Gitane and Motobecane tended to use smaller tubing sizes. Raleigh used 27.2 mm as a standard for most frames.
Regards, Steve Neago
"Just wondering in Cincinnati, OH"