This helps me explain to a new entrant a lot about why that 49cm Cervelo tri-bike fits him a lot like my 54cm Centurion Ironman.

And also why I'm 5'6 w/long legs and ride this 60cm Centurion Carbon. First, the measurements are off because of the frame construction and Second, the "boys" are a little more intimate w/the TT, but I'm having no problems whatsoever.