It is bunk because it is too simplistic. Crank length/pedal stack height/ shoe sole thickness isn't accounted for. WTH?!?!? (Hint the saddle height difference between a 170mm and 180mm is huge in relative terms for any given leg length)

Besides Patriot claims the formula he is using doesn't even take into consideration seat set-back. (adjustment on the seat rails is independent of the formula WTH?!? again! )