Originally Posted by
speedevil
This is an interesting math exercise that has been largely replaced by web-based spoke length calculators, linked to nice databases for hub dimensions and rim ERD values. I always measure rim ERD for myself and measure at at least 2 different points around the rim. And I always check the supplied hub dimensions for myself.
Nice! Granted, I haven't built a lot of wheels, but I always do all of my own measurements and calculations. This lets me be precise about how I want the spoke ends to end up relative to the nipples, and to confirm that all of the numbers are accurate.
I use what I think is the same formula, but in the form of a brief Python notebook, where I also keep all of my previous calculations.