Originally Posted by
deacon mark
I already have the 14mm nipples that is with the current spokes I am using. I fully understand the issue of 12 vs 14 mm nipples.
Are you sure?
It depends on the brand...
If you go to DT Swiss spoke calculator and run the same rim/hub measurements with 12mm, 14mm and 16mm nipples, you will see that the 14mm one needs a 1mm shorter spoke compared to 12mm, and 1 more mm shorter for 16mm. I snatched this figure somewhere quite a while ago:
DT Swiss nipples
-- for every 2mm of length they add 1mm of thread.
This is not the case for Sapim and others, those probably follow what
mack_turtle and aggiegrads say. So if you have 14mm Sapim nipples going to 14/16mm DT Swiss may get you extra 1/2mm. I understand the problem with the nipple breakage at the head, but we should probably ask DT Swiss engineers about it 
Also, there is a database of ERDs and some other data: Browse Rim Database | Freespoke - may be of some use for you.