I may be at risk of repeating somebody by posting this link, but to those of you who haven't seen it, then it's very interesting.
http://www.sheldonbrown.com/seatpost-sizes.html#a
http://www.sheldonbrown.com/seatpost-sizes.html#a
tintin40":b9swyls9 said:no Trimbles either. 26.8 and later i think went up to 31.8 but when
tintin40":2kbul98o said:no Trimbles either. 26.8 and later i think went up to 31.8 but when
icantthinkofausername":3nv3fuz7 said:tintin40":3nv3fuz7 said:no Trimbles either. 26.8 and later i think went up to 31.8 but when
Are you sure it isn't 31.6?