Ahem… shameless plug but…
http://www.unicycle.uk.com/shop/shopdisplayproduct.asp?catalogid=265
jus’curious,why a 22.2 seat tube?
it fitts both the myata 22mm seatposts and the cromolly Bmx rail type seat-posts.
If you want versatility then it’s the best option.
If you want a bigger seat-post, then let me know and I’ll build you one with whatever size you like.