The term GS, short for Gelande Strasse, when applied to motorcycles, has become synonymous with large and imposing swiss army knife bikes from BMW. The original BMW GS was 800cc, and they have only gotten larger and more sophisticated since then. However, the origin of GS bikes was very different. Scrambles/Cross Country/Enduro machines from the 1950s and 1960s had to be light but durable. They typically competed in multi-day trials over varied terrain and needed to be simple and easily maintained. That rugged reliability and light weight resulted in the development of small-displacement go anywhere, do anything machines for the public to purchase. To be fair, many of these were little more than a street bikes with a high pipe, but they all offered the promise of competence on the trail (Gelande) and on the street (Strasse).
By the early 1960s, Zundapp was operating from Munich, having moved from Nurenburg in the 1950s. They were concentrating on producing small 2-stroke machines (both two-wheeled, and four-wheeled). However, they seized upon the opportunity to enhance the brand by competing in the International Six Day Trials (ISDT which later became the ISDE using the E for Enduro), which were the ultimate test for a European machine at that time. While other marques were entering machines close to showroom stock, Zundapp carefully prepared the chosen machines for competition, and soon began to feature prominently on any West German podiums. Given that German teams won almost every year throughout the 1960s, Trials/Enduro machines emerged as a strong point for Zundapp as they continued to excel in motocross/enduro events across Europe. Although they also had some success with larger bikes, the small 2-stroke machine was their sweet spot. Simultaneously, the motocross/enduro scene was exploding in America, and the USA sent teams featuring the likes of Steve McQueen to compete in the ISDE.
“Win on Sunday, sell on Monday” was heartily embraced, and a line of machines was produced for the public. Like all of the German marques, Zundapp had an eager eye on the lucrative US market. For that important market, Zundapp offered the 125cc version in three formats: the MC 125 (motocross), GS 125 (enduro), and KS 125 (street). They were single cylinder 2 stroke machines producing 18-20 hp, and weighing just 210-240lbs. They featured a Bing carburetor, had 5 speeds, and were capable of a top speed of 71mph. If you wanted a much sought-after Rickman 125cc in the early 1970s, it came exclusively with this Zundapp engine and gearbox. Zundapp went on to win World Motocross Championships in 1973 and 1974 in the hands of Andre Malherbe and cemented its place as a producer of premier motocross machines.
Despite their success and quality, sales were never robust in the US where there was fierce competition and better distribution from the Japanese brands. There was also further competition from fellow German marques Maico, MZ, and Spanish entrants like Bultaco, etc. Zundapp paid the price for clinging to 2 strokes as the world rapidly went 4 strokes. Sales declined, and they finally closed their doors in 1984. The name was later sold to a Chinese manufacturer. However, the GS125 remains a vintage favorite. Of course, much later in the 1980s, the GS label was reintroduced on another German production motorcycle.