I normally enjoy reading the technical specifications and opinions in these articles and don't comment on small technical errors, but this one jumped out at me
remember stiffness if calculated from the fourth power of tube dimensions. The 0.7-millimeter tube is 15.4 percent stiffer than the 0.6 tube.
This is a curious statement about fourth powers. ~k^4 applies when both the diameter and the wall thickness are increased by a factor of k (Reynolds 531 DT vs TT). ~k^3 applies when only the diameter increases by a factor of k, but not wall thickness (Columbus SL DT vs TT). ~k^2 applies when diameter is increased by a factor of k, but wall thickness is reduced to keep mass the same (thinwall OS vs standard). ~k^1 applies when diameter is constant and the wall is increased by k (the example given in the article). Note that 0.7/0.6 ~= 16.7% (k^1), and the difference compared to the cited 15.4% can be explained by the fact that the additional wall thickness is added to the ID of the tube.