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 NSU - 250 Rennmax World Champion
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Photo ou archives : F-M. Dumas

Capacity : 250
Model : Rennmax World Champion
Production : 1953 - 1953
Category : (R) Racing


Rennmax / World Champion - 1953

Doing things by halves - successfully!

After abandoning its old single designed by Walter Moore, NSU unveiled a supercharged 350 twin with two overhead camshafts in 1938. The outbreak of war and the ban on forced induction put an end to this project, but t.he Neckarsulm company was on a roll. The same engine served as a basis in 1951 for the record-breaking 350 and 500cc machines, which recorded speeds of 189 and 211 mph ridden by Wilhelm Herz.

Gradual Evolution

Some of the record-breakers' features like the twin shaft drive for the two overhead camshafts were used on the Rennmax, which dominated the circuits in the 1950s, but its evolution was a gradual process. NSU designed a 500cc four developing 53 hp at 9000 rpm, but it proved too fragile and was abandoned; from that project, a 125cc single and 250 twin were evolved.

Twin-Cylinder Challenger

Faster than many 350s of its day, the 250 Rennmax was the sole twin-cylinder machine to challenge the four-stroke singles. It made its racing debut in 1952, ridden by Werner Haas. Six months later, the Rennmax had progressed from 25 hp at 9000 rpm to 29 hp at 9800 rpm and finished second behind the four-valve Guzzi ridden by Lorenzetti. It was the start of two years of absolute supremacy. Improved further, the 1953 Rennmax adopted a new pressed-steel frame from which the engine was suspended. That year, Haas was the first German world champion and only the second rider to achieve a winning double by also taking the 125 title.


Engine: 247cc (54x54mm) air-cooled twin-cylinder four-stroke

Power Rating: 31 hp@ 10,400 rpm

Valves: twin shaft-driven overhead camshafts

Fuel System: two 1 inch carburetors

Transmission: 4-speed; chain primary and secondary drives

Suspension: leading link (front); swinging fork with two spring/dampers (rear)

Brakes: drum (from & rear)

Wheels: 18 inch (front & rear)

Weight: 406 lb

Maximum Speed: 130 mph

The 1953 Rennmax had a superb hand-beaten aluminum fairing; also shown (inset) is the engine of the tubular-framed 1952 Rennmax 250.

Le fichier Moto Passion réalisé par François-Marie Dumas réunit près de deux mille photos accompagnées d'un historique très complet des machines présentées.
Il sera progressivement mis à jour ici et toute information complémentaire est la bienvenue sur info@moto-collection.org.

Cette documentation unique, qui constitue sans doute l'encyclopédie la plus exhaustive jamais écrite sur l'histoire de la moto, a été réalisée avec l'assistance de nombreux spécialistes dont principalement Didier Ganneau, Christophe Gaime, Mick Woollett, Jean Goyard, Bernard Salvat, Christian Rey, Yves Campion, Helmut Krackowizer, Michael Dregni, Michel Montange, etc. que je remercie ici.

Disponible sur demande :
- Les fiches originales sur papier
- Les photos et archives signées de mon nom en haute définition ou les documents originaux.
Me contacter sur info@moto-collection.org pour les conditions et droits d'utilisation.