The cycles he thought he saw are at best quasi-periodic meaning there appears to be a pattern but the time period changes enough that where we are in the cycle is subject to interpretation.
Similar to the "alternative wave counts" in Elliot Wave Theory.
In addition most of the early work was done before central banks and fiscal lunatics distorted business cycles beyond recognition.
(I know, "it's not a business cycle, it's a price cycle")
There is something to the long cycles as a framework on which to hang experience, but as with all models, one must guard against "seeing what you want to see" and/or seeing more of a pattern than is actually in the data.
From The Telegraph:
One of my earliest introductions to the world of economics came from someone who was a true believer in the Kondratieff Wave – the idea that there is a much longer cycle, lasting approximately fifty years, which overlays the ordinary, and shorter business cycle. You'll be pleased to know that if the present crisis marks the start of a classic Kondratieff downswing, then we've got between five and thirty six years of slump still to come.That "true believer" in the first paragraph is a tell. It says we are delving into something more akin to religion or mysticism than science. Also, the K-waves are not falsifiable, the most basic requirement of science.
In any case, it was a delight to have my attention drawn via a reader letter to the editor to a Sunday Telegraph article, published in October 1987, which postulated that the stock market crash of that month marked the crest of a Kondratieff Wave, ergo it would therefore be down hill from then on for the next 20-30 years. Well there was a recession shortly afterwards, albeit shallow and shortlived, but thereafter decent levels of growth resumed and continued but for another brief hiccup around the turn of the century right up to the present crisis.
Nor was this the only error in prediction. Kondratieff Waves tend to be associated with the eclipse of one world superpower and the rise of another, so it was logical to assume back then that the still apparently unstoppable rise of Japan would eventually dislodge the United States from its position of economic hegemony. How wrong can you be.
However, none of this disproves the Kondratieff theory. The mistake made in The Sunday Telegraph article may have been merely to misread the cycle. Kondratieff, a Russian economist who died in Stalin's Gulags, identied three distinct long waves, the dates of which you can see in the table below. The downswing in the last of these waves begins during the First World War.
Subsequent students of Kondratieff cycles have placed the end of this third cycle during or shortly after the Second World War, which seems logical enough, and have identified a further two cycles thereafter, with the fifth upswing beginning in the 1980s and ending with the current crisis. On past durations, we are now in a downswing phase lasting anything between ten and forty one years. Dating the beginning of the crisis from 2008, that's between five and thirty six years to go (See table below)....MORE
(along with "reproducible:)