Originally Posted by
Fred Smedley
Reputable wheel builders that I have seen seem to universally agree that a DB spoke builds a stronger , more durable wheel . A straight gauge spoke has to flex at the ends , which is where spoke failures mostly occur.
+1 but we have to define strength.
Wheel stiffness is proportional to the total amount of steel, so more or thicker spokes build a stiffer wheel
Likewise total load capacity is proportional to the amount of steel, so more or thicker spokes raises the static load capacity, BUT a chain is only as strong as it's weakest link. The strength of spokes at the elbow (in shear) is only 80% that of what it is in tension, so as long as the cross section of a butted spoke spoke is 80% or more than at the elbow the spoke is just as strong despite being thinner. A similar calculus applies at the threads, so any material in the spoke beyond the root diameter of the thread doesn't add strength.
Lastly is life expectancy, which is the kind of strength that most of us are most concerned with, and butted spokes win hands down. Butted spokes move the majority of deflection away form elbows into the thinner sections, increasing the fatigue life at the elbow. Since metal fatigue is the most common non-crash cause of wheel failure, it's safe and accurate so say that
butted spokes build a stronger wheel.