I've built quite a few wheels over years, both motorcycle and bicycle. I actually learned on motorcycles and came "back" to bicycles. All the wheels I've built had symmetrical spoke hole drillings. Now I'm attempting to build a wheel using a rim with asymmetrical spoke holes.

Here are the particulars:

1) Velocity Synergy 700c OC rim.

2) NOS 2002 Vintage Campagnolo Veloce 9/10 rear hub.

3) 36h 3X Cross.

I used two spoke length calculators:

1) Roger Musson's "Wheelpro" Spoke Calculator

2) Damon Rinard's Excell Spreadsheet(Spocalc)

Here are the results:

Wheelpro:

Left Spoke Length -- 292.4mm Right Spoke Length -- 290.7mm

Spocalc:

Left Spoke Length -- 292.7mm Right Spoke Length -- 290.9mm

The average difference between the left and right spokes is 1.75mm.

Here is my question:

With both spoke length calculators, I entered a rim offset of zero. I went to the Velocity Rim site, but could not find any specs for the offset of the OC rims. Will the rim offset make much of a difference in spoke length calculations, and if so, how do I measure the rim hole offset?

Any help will be greatly appreciated.