In this thread in another forum, I calculated the coordinate speed of light as measured by a distant observer. As far as I understand it, the length contraction in GR is only in the radial direction, right? None tangent, correct? The time delay of light found, though, trying different examples, was always 20 microseconds smaller than the values measured by Shapiro. However, when I use the coordinate speed of light c' = c (1 - 2 G M / (r c^2)), with the same length contraction regardless of direction, it then matches the equation used for the Shapiro delay and the data measured. What does this mean?