Bumble Beemer

Text: Robert Smith • Photography: Robert Smith

I once asked a BMW car marketing guy what differentiated his company's image from rival Mercedes. "Simple," he said. "We build motorcycles; they build trucks."

And considering its traditional image as a maker of staid and stolid motorcycles, BMW has an impressive record of performance innovation: the first factory-faired sport bike, the 1976 Daytona-winning R90S, for example; more recently, the astounding K1200R, the world's fastest street standard; and the bike that created the adventure touring category, the R80G/S of 1981.

Often emulated, never quite rivaled, BMW's GS series remains the benchmark for "big trailies": the bikes that the GS range has inspired since 1980, including the Cagiva Elefant, Triumph Tiger, Moto Guzzi Quota, Aprilia Caponord, KTM Adventure, Suzuki V-Strom, and (outside the US) Honda's trio of twin-cylinder trailies, the Transalp, Africa Twin, and Varadero.

ISDT and Paris-Dakar
In the late 1960s, BMW almost quit making bikes. They needed capacity to build more cars, the motorcycle market was in a downturn, and the aging R60 and R69 were essentially obsolete. But motorcycles are about performance, a trait BMW wanted buyers to associate with its cars; so instead it lured Hans-Gunther von der Marwitz from Porsche to re-invent its motorcycle range. Thus the "slash" series of BMW boxers was born, the /5, /6 and /7s, built in a new factory in Spandau, just outside Berlin. Von der Marwitz's basic design was so good, it ran until the last "airhead" twins of 1996.

Though von der Marwitz retained the opposed-twin layout, he completely revised engine internals, using a one-piece forged crank with plain bearings, moving the camshaft below the crank, and driving it by chain, not gears. A handsome aluminum casting housed the alternator and other ancillaries, while an engine speed clutch drove a four-speed gearbox (in the /5) with - as all BMW's had up to that time - shaft final drive

The International Six Days Trial (now Enduro) has been a proving ground for motorcycles since 1913. Helmut Scheer entered the 1970 competition on a modified R75/5, winning silver, and Herbert Schek took the gold in 1971 and 1973. For 1979 and 1980, BMW successfully entered the new over-750cc class with the competition-only GS80. But the company was eyeing a bigger prize.
First run in 1979, the Paris-Dakar rally had caught the public's attention. Yamaha XT500s won in 1979 and 1980, but BMW planned a major assault for 1981, with its latest creation: the R80G/S.

G/S
Something of a parts-bin special, the R80G/S employed the 800cc R80/7 road-bike engine in a modified R65 frame. The revolutionary complement, however, was the rear suspension, using the shaft drive housing as a single-sided swingarm. The Monolever, as BMW named it, offered extra torsional rigidity and lower weight. The G/S was a tall bike with good ground clearance, motocross-style handlebars, and long suspension travel. The full-size adventure tourer was born.

HPN Motorradtechnik, a small Bavarian company of ex-factory race engineers working with BMW France, prepared three special R80G/Ss for the 1981 Paris-Dakar. They finished first, fourth, and seventh. BMW won the event in three consecutive years (1983-1985) with a bigger-engined 1000cc version.

GS
The "G/S" designation ("gelande/strasse" or terrain/street) implied off- and on-road use. BMW's own research showed that G/Ss were used 98 percent on-road, so their revised 1987 model was more street-oriented. The Monolever rear suspension had also drawn criticism: torque reaction would "jack up" the rear end under hard acceleration, upsetting the handling. BMW added a torque rod to the outer casing to create the Paralever and launched the R80 and R100GS ("gelande-sport") with revised bodywork. With 40mm Marzocchi forks replacing the earlier 36mm BMW units, the rear wheel was now 17 inches (all G/S and GS bikes have 21-inch front wheels), and special alloy rims with rim-edge spokes allowed tubeless tires.

Overall, the new GS was bigger, heavier, and less "off-roadable," but struck the right note for its intended market. Offered alongside was a Paris-Dakar version with 35-liter fuel tank, hard bags, luggage rack, and front impact bars. For 1991 these features (except the 35-liter tank) were incorporated into the GS, with a new color scheme of black with yellow highlights that earned the nickname "bumble bee." The R100GS was last produced in 1996, when the four-valve, oil/air-cooled R1100GS replaced it.

Riding the GS
At well over 500lbs with fuel and oil and a seat height of 34-plus inches, this is a big, heavy motorcycle, and it takes some effort to roll it off the stand. The engine fires with the expected lurch, then settles to a rocking idle. Refreshing my memory, I check out BMW's Lego-look handlebar controls: turn signal buttons on both bars, and the 'cancel' switch under the right grip.

Any Beemer twin, especially the GS, feels odd after a "regular" bike, but once rolling, the GS is easy to handle, no doubt partly because of the wide bars. The controls are light, the instrumentation clear and simple, and the handling neutral, though the brakes do require some "anticipation."

With just 60 bhp, it's not fast; but the GS scores with low-down torque and a broad powerband. The way to ride it, I discover, is to carry its momentum through each bend using the engine to control speed. The compliant suspension throws the odd weave, but traction is remarkable. Tires squirm under load but never seem to break away. I start to understand the appeal of the big brute. On broken tarmac, it would waltz around a sportbike. Add all-day comfort, simple low-tech maintenance, and serious durability and I realize why, for many long-distance riders, the "airhead" GS is still a top choice.

TECHNICAL SPECS:

1991 BMW R100GS

Owner Geoff May, Surrey, BC, Canada
Engine 980cc OHV opposed twin, air-cooled
Bore & Stroke 94mm x 70.6mm
Compression 8.5:1
Output 60hp@6,500rpm, 56 ft- lbs@3,750rpm
Lubrication wet sump
Carburetor Bing V64 II (2)
Ignition Bosch electronic
Transmission engine speed single-
plate dry clutch, 5-speed gearbox
Final Drive shaft
Front Suspension Marzocchi 40mm telescopic, leading axle
Rear Suspension paralever, Boge gas shock
Lighting 12v/25Ah battery
Frame steel tube, duplex cradle with bolt-on rear subframe
Wheels Akront alloy with rim-edge spokes, front 1.85 x 21in, rear 2.5 x 17in
Tires Front 90/90 x 21in tubeless, rear 130/80 x 17in tubeless
Front Brake 285mm (11.2in) Brembo disc
Rear Brake 200mm (7.9in) BMW drum
Fuel Capacity 24 liters (5.3gal), PD: 35 liters (7.7gal)
Wheelbase 1514mm (59.6in)
Seat Height 830mm (34.6in)
Weight (dry) 207kg (455lb)
Weight (wet) 236kg (520lb)