Tom Harriman asked: However, if there's a list member with a PHD in spook life, there free to enlighten the rest of the list.
Capt. Bike, PhD in all things bicycles, the late Sheldon Brown put it succinctly and correctly on his Website: "Double-butted spokes do more than save weight. The thick ends make them as strong in the highly-stressed areas as straight-gauge spokes of the same thickness, but the thinner middle sections make the spokes effectively more elastic. This allows them to stretch (temporarily) more than thicker spokes.
As a result, when the wheel is subjected to sharp localized stresses, the most heavily stressed spokes can elongate enough to shift some of the stress to adjoining spokes. This is particularly desirable when the limiting factor is how much stress the rim can withstand without cracking around the spoke hole. "
My 30 years of experience building wheels leads me to concur. I have see far fewer broken spokes and cracked rims with butted spokes laced tight.
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