Which is exactly my point... Reach is not independent of Stack. Stack consistently tells you what you'd have to do to get your bars at the correct height... but Reach isn't a consistent value that tells you what you need to do to get the bars in the correct lateral position. I'm talking about a number that is a property of the *frame* that represents its "reach". Reach doesn't do it.

As an example, I'm comparing two frames, because I need to decide which one is the best fit. One has a 500mm stack and 410mm Reach. The other has a 530mm stack and 410mm Reach. If a 110mm stem with 30mm of spacers gets me in the correct position on the first frame, shouldn't I expect the same stem with 0 spacers to put me in the same position on the second one? After all, the Reach is the same... but I need a 100mm stem to get the same fit. Wouldn't it make more sense if the Reach was independent of Stack? If you always measured Reach at a fixed distance above the bottom bracket (instead of the top of the headtube), then it *would* be consistent.