Hi Nick,

it is much better to have an equation with all the measurements included, so you are not dependent on which hubs/rims are in the list...

You need to know:

a=distance of the flanges in mm

b=flange diameter in mm (measured from hole to hole)

c=number of crossings of the spokes (zero for radial lacing)

d= number of spokes

e=diameter of the rim in mm (measured where the nipples are, often given as "ERD": effective rim diameter)

Then you have to calculate this (use Microsoft Excel for example):

Spokelength=square root(0,25*(a^2+b^2+e^2-(2*b*e*cosine(pi/180*720*c/d))))-1,5

I have found this equation somewhere in the web. The -1,5 was found empirically by me, it was more accurate for my wheels... It should give you a length about plus minus 0,5 mm.

I hope this helps.