1946 – As during the First World War, sporting events disappeared from all the calendars, but the motorcycle confirmed its great tactical importance in every field of battle, and went forward on an inexorable technological progress.
The knowledge acquired during the war continued to bear fruit even in time of peace, circumnavigating the world.
The reed valve, for example, the first application for which was on a two-stroke NSU engine, dates back to 1920 and was markedly improved as a result of its use on Vergeltungswaffe (the flying V1 and V2 flying bombs) developed by Werner von Braun in the famous Penemünde polygon on the Baltic Sea.
Reed valves were manufactured at Porsche, and their development helped Walter Kaaden such that, a few years later, he went on to direct the racing department of MZ, in the former GDR.
Winning the World Championship Cross 250 cc class in 1973, by an official Yamaha complete with reed valve was just one of many valuable applications of what for decades was considered a military secret.
The Second World War literally shocked humanity, and when finally it was put to an end, it was realized that nothing was as before. The world, in fact, emerged from the conflict completely changed and divided into two opposing blocs.
The United States of America and Western Europe, which had irrevocably embraced a libertarian and democratic choice, was now confronted by repressive regimes, communist-inspired and led by the Soviet Union.
Economically and ideologically opposed, they found themselves at the same venues, albeit with different motivations.

While the industries of the West regarded the competition as a great advertising and commercial vehicle, to the east it was the powerful military establishment that showed an interest in the sport, which they considered an excellent test to assess the actual capacity of its motorized battalions.
On these occasions you could see cars and riders on the field, but also the organization of departments, communications, logistics and detailed military maps.
This dual role, which allowed going beyond the mere sporting event, encouraged participation, with large deployment of resources by industries of the East, of the so-called "Soviet bloc", otherwise absent in many other motor-sports disciplines that did not show similar military interests.
Compared to the competition that preceded the Second World War, there was also a radical change in the choice of circuits, and the shift from road to off-road was its logical consequence, and also its apotheosis.
The sidecar class was but one of many implications for the military, and their presence lasted until 1956, when the circuits began to become impossible, but even when all land transports were overcome and made ​​obsolete by the new emerging science, rocketry.
The big Eastern teams continued to participate in competitions that followed, helping to increase the general interest, thanks to the advanced technology of their bikes and funded directly by the state and strong with advanced technologies, at least until the end of 70s.
In the collective imagination, they were presented as men and equipment specially prepared for any type of road - rangers able to easily penetrate the enemy flanks and open the way to the Red Army, who, victorious, would bring progress and freedom around the world.
With hindsight it is legitimate to smile and breathe a sigh, but those were the days of the Cold War and even a sporting competition like the Olympics or the ISDT had lived as a real military exercise, with the inevitable involvement of international spies, stolen military secrets, adventure stories and heavy diplomatic crises, such as the daring escape of a famous engineer engaged in development, the MZ rider Ernst Degner, who in 1961 went over to Suzuki where he contributed decisively to the development of a new generation of racing motorcycles that quickly reached the top step of the podium.
For this reason, there were low blows from both sides. Some Six Days that took place in the East were troubled by mysterious episodes of "sabotage", always to the detriment of foreign teams, balanced, to be fair, by a similar behaviour on the western side, every time that "our" commissioners interpreted the specious regulations, always to the detriment of the team behind the Iron Curtain.
Apart from some inevitable questionable results, eastern bikes, for years at the top of the world rankings, collected many wins and were among the major protagonists of the first thirty years of the sport.
The spearhead of their production was represented by the DDR machines, Simson and MZ, and from Czechoslovakia, the Jawa and Tatran, but until the mid-70s, the Soviet Union took part with their teams and their bikes in the most important international competitions.
The same military logic which had facilitated the development, obtusely made ​​useless every effort in the commercial arena, since it imposed a strict military secret which prevented this large funding from becoming profitable and generate an adequate financial return.
In the 70’s, in fact, Western companies were definitively overtaken, thanks to the fact that the motorcycles produced were sold in the West and their economic success allowed the various manufacturers to find the funds necessary to continue research and investment, which then became important at the end of the eighties in causing the collapse of the entire communist bloc.
This was not the only difference between East and West, because they changed the market segments also.
While the West was more interested in the commercial aspect of mass motorization and was then concentrated on medium-low displacements around the 125 class bikes that were cheaper and more accessible to the general public, the East looked with interest at the most suitable classes for military use, and for the 50’s and 60’s these were placed at around 250 cc.