"Calfee says the unusually looking bulge in the down tube was necessary to handle the extreme stresses in that area, particularly when combined with the huge S&S coupler"

http://www.cyclingnews.com/features/photos/nahbs-2014-gallery-traditional-road-bikes-dominate-the-floor/297265

Actually, that bike just swallowed a good sized mouse.  Don't believe me?  Think about a snake.  What it would look like if you put an S&S coupler on it.  (THe Calfee crew are excellent engineers but they flunked anatomy.)

Ben