I want to build a rear wheel with a 3 cross double twisted spoke pattern. Has anybody had any experience with this? How do you figure out spoke length? Do you have to use special/longer nipples? Double butted vs. straight gauge? Any special precautions? Thanks!

Quoting Gerd Schraner from "the Art of Wheelbuilding"

The twisting of spokes, instead of the classic crossing method, is a waste of time for road use. tests have shown that it results in a very unstable wheel. The lateral stability is about the same as a normally spoked wheel, but, radially, the wheel reacts so sluggishly that encounters with momentary overloads (bumps in the road) the highly praised damping effect is delayed.

The exercise is only useful for trials sport, where the bike is momentarily held at a standstill after hard landing and hopping tricks.

Twisted spoking patterns are not only unaesthetic but are an additional mechanical disadvantage resulting from the extreme angle of the spoke directly at the nipple.

Every serious wheelbuilder who has ever practiced this kind of spoking pattern has sworn to refrain from repeating the error.

Yet, young bike freaks, apprentices and mechanics seem to like this kind of spoking pattern.My advice: leave them at it and let them continue to show their enjoyment and enthusiasm in this way. Its better to see them rolling spokes than rolling joints.

The last line is my favorite bike repair book quote Evar!

In the interest of actually answering the question: spoke length is a tough one. I'd probably draw out the pattern to scale, come up with a triangle out of that, use a straight spoke length for the base of the triangle, and use some basic trig to figure out how long the rest of the triangle is. Add the other two side lengths together, and add maybe 2mm per twist?

Agree that it's not a high-quality build, but it sure can look nice:

Totally agree with Cavernmech. Twisted spokes are pointless and make a poor wheel. Used to do these Snowflake pattern wheels for young jumping tigers many years ago but stopped doing them as they were laterally not very strong. If you landed with the wheel anything other than vertical, they pretzeled. If you are determined to have a go, add about 5mm to each spoke length to allow for the twist.