The BMW R 100 RS changed expectations… forever

BMW R 100 RS

Ian Falloon

When BMW launched the groundbreaking R 90 S 50 years ago, it changed the popular notion that BMW motorcycles were sturdy, sturdy and suitable only for wealthy old people. Hans A. Muth has created a masterpiece of styling and the R 90 S is a true Superbike.

However, while quick and comfortable, it faced some criticism for its high-speed stability and offered only minimal weather protection. The high steering inertia of the handlebar-mounted fairings further accentuated this instability and about a year later, Muth was asked to create a new motorcycle with a more integrated aerodynamic fairing.

The result is the R 100 RS, which is arguably even more important to BMW than the R 90 S. RS stands for Rennsport and was used deliberately to create an association with 54-axle RS racers The stunning twin cam of 1954. Beneath the massive fiberglass fairing was also the most powerful incarnation of the boxer, and the R 100 RS created a stir when it was launched at the Cologne Show at the end of the year. 1976.

The R 100 RS is the first motorcycle equipped with a fairing for rider protection, aerodynamics and motorcycle stability. Hans A Muth and Günther von der Marwitz rented the Pininfarina wind tunnel in Italy to develop the R 100 RS fairing.

It cost BMW $7,000 a day, a significant sum in 1976. The 9-piece fairing design was so advanced that it continues to be the benchmark for motorcycle fairing performance and very few later examples have can compare with it. The RS fairing is said to reduce front wheel lift by 17.4%, drag by 5.4% and sidewind yaw moment by 60%.

All this, with a weight penalty of just 9.5 kg. But the R 100 RS is more than just an effective shield. The engine has a diameter of 94 mm to provide a capacity of 980 cc, and with larger valves, the power is up to 70 horsepower at 7250 rpm.

Instead of the R 90 S’s 38 mm concentric “pump” Dell’Orto carburetor, the R 100 RS received a 40 mm Bing constant vacuum carburetor. Although the frame and swingarm are essentially unchanged, a second cross tube has been added between the twin front exhaust pipes and the frame tube which is a thicker section.

Despite these welcome improvements, the front fork still includes a weak pressed-steel upper triple clamp and the rear subframe remains bolted on as before. Most early R 100 RSes were equipped with spoked wheels and rear drum brakes, but from 1978 all RS models came with snowflake cast alloy wheels with rear disc brakes.

If the R 90 S pushed the boundaries of sport with its low handlebars and semi-racing riding position, the R 100 RS went one step further. The narrow clip-on handlebars are mounted inside the fairing and provide a surprisingly aggressive riding position.

Considerable weight is placed on the wrist, encouraging high-speed movement. There’s also the choice of standard double seats or sporty solo seats, almost one and a half.

Updates to the R 100 RS were made almost every year until arguably the best model, the 1981-84 series. In 1979, the camshaft drive was completely revised, an automotive-style rotary contact breaker ignition was fitted along with an oil cooler and torsional vibration dampers were added to the driveshaft.

In October 1979, an R 100 RS was prepared for an attempt at a series of long-distance records. At Nardo in Italy, a team of four riders (Dähne, Cosutti, Milan and Zanini) set five new world records, including an average speed of 220.711 km/h over 100 km.

Most of the development was devoted to the 1981 model. This year saw Galnikal cylinders, electronic ignition, a plastic airbox with flat air filter, and a much lighter flywheel and clutch assembly. , with outstanding Brembo front brakes. The front brake master cylinder has also been moved from underneath the fuel tank to the handlebars.

Although the K 100 RS was intended to replace the R 100 RS from 1984, public demand saw it return only two years later. The revived R 100 RS lasted until 1992.

The R100RS was one of the most expensive motorcycles of the late 1970s and early 1980s. And despite retaining a relatively simple engine, it was able to compete with any sport touring motorcycle. any other calendar, even its replacement, the four-cylinder K 100 RS.

The curb weight of 210kg and the combination of a large 24-litre fuel tank, long-travel suspension and fairings make it a one-of-a-kind road-burner. Even today, the R 100 RS remains a high-performance sports touring motorcycle, one that is particularly well suited to modern pothole-filled highways if the mandatory speed limit is not exceeded. .

While the K 100 has sunk into oblivion, the R 100 RS is another BMW masterpiece. Easy to maintain and reliable, the R 100 RS is a bargain classic.

BMW R100 RS technical specifications