Originally Posted by cyccommute
I was unable to find any figures at all for the Atlantis on the Rivendell website (I checked) so I went with the number provided.".
Easily found:
http://rivbike.com/html/bikes_atlantis_5.html
The 44.0 is for the smaller 559 (26") wheel frames. The chainstays lengthen to 45 and 45.5 cm as sizes increase, which makes sense. My size (I'm 5'11") has 45.5 cm stays.
Thanks, Alekhine, for a very elegant response. Mercian sounds like a wonderful company, and I'm sure your KOM is a fantastic tourer. Mark, the OP, should also consider them, based on your report.