Spoke Length: Determining Spoke Bed Offset

[bobscott]

I want to build up a rear wheel using a Velocity Synergy O/C rim and am working on spoke lengths.

Does any one know how to measure the lateral spoke bed offset (OSB) for Damon Rinard's spokcal program (http://www.sheldonbrown.com/rinard/spocalc.xls)? Velocity does not list an OSB. FWIW, the program does list a Velocity Aerohead O/C as having a OSB value of 4mm.

Here's my main stumbling point. The program describes OSB as rim offset from wheel center rather than rim center. I know these should be the same but would like some one to second my thought.

I was thinking of calculating the OSB by taking the difference between 1) half the entire width of the rim and 2) the distance from the rim side to the center of the spoke holes.

Any ideas on this?
Thanks,
bobscott

[ergott]

I measured 3.5mm offset with those rims. I measure the overall width. Then I measure to the center of the spoke hole. You have to do this to two adjacent holes as they are offset to each flange as well. Then you take the average. Even if I'm off by .5mm, it will not make a significant difference in the spoke lengths as ERD is the biggest factor in spoke length.

[bobscott]

Expected an answer from you....Thanks, Eric.

bobscott