Originally Posted by
PeteHski
When I see a manufacturer quote Stack and Reach I take it for granted they will be quoted with the original fork that comes with the bike. Same goes for all other fitting parameters which are dependent on the orientation of the frame relative to the ground plane.
Fork length only becomes relevant if you decide to change it.
Yeah, that was part of the discussion that RChung linked. He describes a (rare) situation where it was relevant.