Thanks for the note, RB. That's what I'm thinking. I measure it to about 26.5, with the assumption that the top of the ST might not be perfectly round. The ebay seller had the seatpost and said it was stamped 26.2 (I saw the stamping in the pic). But I just ordered a nice 26.4 from a source for not much money. If it doesn't fit I'm not out much. I'd rather have a better fit even if it means I have to clean up the ST a little.