Originally Posted by cyccommute

Pillar Spokes doesn’t present testing in a laced wheel but they appear to have measured the breaking strength of all of their various spokes. They likely used some version of a machine like an Instron tester. You have to click through all the spokes to see the data. Comparisons of the various strengths means flipping back and forth between several pages so it’s not the easiest to use but it’s the only real data I’ve ever found.

I have screen captured some of their graphs in the past.

Straight gauge
Image 5-11-18 at 1.41 PM by Stuart Black, on Flickr

Double butted

Image 5-11-18 at 1.44 PM by Stuart Black, on Flickr

Triple butted

Image 5-11-18 at 1.43 PM by Stuart Black, on Flickr

You can see a clear increase in strength with butting and with increased head diameter. Looking at the 2.0mm spoke, going to a 2.0/1.8/2.0mm (1415 on graph) there is an about a 10% increase in strength. Going to a 2.2/1.8/2.0 (2018 on graph), there is a 22% increase in strength over a straight spoke. Pillar makes a 2.4/1.8/2.0mm quad butted spoke that has a breaking strength of 340 kgf or 25% greater strength than single butted.