Seatposts for your classic and vintage bicycle. You can buy here classic seatposts by Colnago, Shimano, SR, Zeus etc. We offer seat posts in the different sizes for your classic race bike. The size 27.2mm is the most popular seatpost diameter for classic bikes. The older your vintage bike the more difficult it may be to find the right seat post for it! There were different standards for different steel tubes. Columbus built steel seat tubes in diameters 26.8, 27.0, 27.2 etc... Feel free to contact us for more information or if you need help in finding the right seat post for your classic or vintage bicycle!