Originally Posted by
Wheever
The spec is a 27.2, and that's what the post is supposed to be. I don't have calipers to check the actual dimensions, but that would be useful to know. Both that and the I.D. of the seat tube.
The post looks small for the frame.
If you have a cloth tape measure the circumference of 27.2 should be 85.45mm, or a little less than 3 3/8". This method is used to measure stuff industrially, often with an invar (low thermal expansion coefficient) metal tape called a "Pi tape". If you don't have a tape measure, use some fiberglass tape. Wrap some around the metal seat post and cut through the bottom layer and the overlapping layer simultaneously. Peel off, tape it to a hard surface, and measure from cut to cut. With a good ruler and careful measurement, you can probably get within +/- 0.5 on the circumference, or within about 0.2mm on the diameter.
The real Pi Tapes get within 0.001", or 0.03mm. A pic, showing the vernier scale on the tape is below.
