So last season I got a closeout set of real design ultrasphere wheels (http://www.real-design.com/2005/usphere.aspx). I really liked the wheels and especially the hubs. In the last race of the season, a cat 5 cut in on me, taking me out and tacoing both wheels.

Now, I've still got the hubs and I just purchased a pair of IRD Noibium 30 rims. I'm having trouble figuring out what length spokes I should use. They're straight pull hubs, not J-bend, which I don't have much experience with them.

My friend who builds wheels for QBP measured the hubs:

Front: 20 hole radial
Diameter: 33mm
Flange to Center: 35mm
Width: 100mm (duh)

Rear: 24 hole radial nds, 2x ds
DS Diameter: 48.5mm
NDS Diameter: 32
DS Flange to Center: 17.5
NDS Flange to Center: 36.5

I plugged these numbers into Sapim's (the spokes I intend to use) spoke calculator and got
275mm front
283 DS, 268 NDS rear

Using the QBP spoke calc:
272mm front
276 ds, 273 nds rear

Which one is right? Thanks.

Plup-in your number in spoke calculator. http://www.damonrinard.com/spocalc.htm use the extended version

And there are plenty of other calculators online if you do a search... and they should all agree. Check your work until they do. BTW, with your numbers I get 273.2 front, 276.7 DS, and 273.9 NDS. I used 577 for rim ERD.

Thanks everyone, checked a couple others calcs and lesson learned: the Sapim calc is way off. Just to double check, on a deep rim, a mm long is better than a mm short, right?

Not always... if the spoke is so long that it goes past the threads it will bind... and this isn't a fun thing to have happen at full tension. Most likely an extra mm will not get you to this point though. It's more likely to happen if you are using light spokes on the DS since they stretch more.