The basic arrangement for cross-laced spokes is thus: Spoke
Length = sqrt[ (RRSP - (HSR * cos(SAA)))^2 + HFO^2 - (HSR *
cos(SAA))^2 ] For radial (straight) spokes, the formula is
simpler: Spoke Length = sqrt[ (RRSP - HSR)^2 + HFO^2 ] - RRSP
(Rim Radius plus Spoke Penetration) is half of the Effective Rim
Diameter given by the manufacturer plus 2mm for the spoke's
penetration into the nipple - HSR (Hub Spoke Radius) is the
radius from the hub center to the outermost edge of the spoke
holes on the hub - SAA (Spoke Anchor Angle) is the angle of from
the hub spoke hole to rim hole that the spoke goes to. It
depends upon the lacing pattern and which individual spoke you
are calculating for. - HFO (Hub Flange Offset) is the distance
from the hub's flange to the lateral center of the wheel, based
upon the dish of the wheel. For a front wheel, this will be the
same on each side, but for a rear wheel, which has a dish to
accommodate the rear gears, this is different for each side
since the hub's own lateral center is