It should be a 27.0, but mine came with a 26.8, which would have disappeared into the frame without the seat (I'll be searching for proper one at my LBS this week, along with a 26.4 for a Mt. Fuji; aargh people, please don't switch seatposts if you don't know what you are doing!).
Here's a pretty cool write up posted by Pbridge (same person with help with this one) about the Allez and Sequoia, also confirms a 27.0 for the Sequoia, and 26.8 for the Allez.
https://www.flickr.com/photos/pbridg...7673422020365/
Originally Posted by
Insidious C.
Congrats on your lucky find! What size seatpost will your Sequoia accept? My 81, 82 and 83 Sequoias all have a 26.6 seatpost. Glad you posted the BB pic which shows under-the-shell cable route used in 81. No bottle bosses on seat tube was 81 and 82 thing.