if you want a strong wheel, you want doublebutted spokes. if spokes break, they break by the nipple or at the head. double butted spokes reinforce these areas, and have thinner central areas - this allows them to flex, which is important in the wheel's strength. if a wheel flexes a little, it will be deal well with impacts. if it cannot flex, it will be brittle and break. ani difranco knows wheelbuilding -

"buildings and bridges were made to bend with the wind, to withstand the world, that's what it takes. all that steel and stone is no match for the air, my friend. what doesn't bend breaks."