27. It came stock with a Kalloy setapost..230mm
Edit to add: Perhaps someone can verify this for me. My 1994 XO-3 has a 27 post but I see alot of XO's also coming with 26.2 Kalloy posts. All of the stems have the same id's (#242 and #243) but different sizes so I am not sure, it will be 27 or 26.2 I guess.
Last edited by Johnny Alien; 08-15-09 at 02:03 PM.