BMW R100GS

International Six Days Trial and Paris-Dakar

In the late 1960s, BMW almost quit motorcycle production. Its cars were selling well, its aging R60 and R69 range badly needed updating, and competition in the motorcycle market was fierce. But motorcycles were associated with performance, a trait BMW wanted to nurture in its cars, so BMW made the decision to stay in the motorcycle industry. The company lured Hans-Gunther von der Marwitz from Porsche and gave him the job of re-inventing the boxer twins. Thus was born the “slash” series of BMW boxers, the /5, /6 and /7s. Von der Marwitz’s basic design was so good it was still found in the last “airhead” BMW’s sold as late as 1996.

Though von der Marwitz retained the opposed-twin engine layout, he completely revised its internals, using a one-piece forged crank with car-type plain bearings (with connecting rods from the 6-cylinder car engine). The camshaft moved below the crank driven by chain, not gears. A handsome aluminum casting that also formed the crankcase housed the alternator and other ancillaries. A car-type clutch and flywheel mounted to the crankshaft drove a four-speed gearbox with final drive — naturally — by shaft. And gone were the Earles forks, replaced by telescopic units. (Curiously, BMW pioneered telescopic forks decades previously before adopting the Earles link-type fork in the ’50s.)

The International Six Days Trial in Scotland has been a proving ground for motorcycles since 1913. Helmut Scheer entered the 1970 competition on a modified R75/5, winning a silver medal, while Herbert Schek won a gold in 1971 and 1973. For 1979 and 1980, BMW entered a new bike, the competition-only GS80 in the new 750cc-plus class with much success. But the company was eyeing a bigger prize.

Starting 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, using as the basis the company’s latest creation: the R80G/S.

G/S

Announced for the 1981 season, the R80G/S was both revolutionary and something of a parts-bin special. It used the road-bike 800cc R80/7 engine in a modified R65 frame.

Revolutionary, though, was the rear suspension, which introduced BMW’s now famous concept of the shaft drive housing forming a single-sided swingarm. The payback for using the Monolever unit, as BMW named it, was 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.

BMW France, working with HPN Motorradtechnik, a small Bavarian company formed by ex-factory race engineers, prepared three special R80G/Ss for the 1981 Paris-Dakar. They finished first, fourth and seventh. Though gearbox problems foiled their 1982 campaign, BMW won the event in three consecutive years from 1983-5 with a bigger-engined 1,000cc version.
The R80G/S was also a sales success, especially in Europe. But BMW was already planning an updated model.

R100G/S

Several factors came together to create the R80GS and R100GS. First, the original “G/S” designation (“gelande/strasse,” or terrain/street) implied the bike was intended for off- and on-road use. BMW’s own market research showed that G/Ss were used 98 percent on the street, so the new bike’s personality would be steered that way. Second, the Monolever rear suspension had drawn criticism: torque reaction from the big boxer engine would “jack up” the rear end under hard acceleration, upsetting the handling. BMW’s answer was the Paralever, which added a torque rod to the outer casing. Together with revised bodywork, the R80GS and R100GS (“gelande-sport”) were launched for 1987.

There were a number of other important changes:
• The 980cc R100GS version
• Oil cooler mounted on the right-hand “engine protection bar” (“crash” bar is considered impolite!)
• 40mm Marzocchi forks replacing the earlier 36mm BMW units
• 17in instead of 18in rear wheel (all G/S and GS bikes have a 21in front wheel)
• Special alloy rims with rim-edge spokes, allowing tubeless tires.

Overall, the new GS was bigger, heavier and less off-roadable than the G/S, but struck the right note in terms of its intended market. Offered alongside was a Paris-Dakar version with larger gas tank, hard bags, luggage rack and front impact bars. These items (except the gas tank) were incorporated into the GS for 1991 as well as a new color scheme of black with yellow highlights, earning the nickname “bumble bee.”

The R100GS was last produced in 1996, when it was replaced by the four-valve, oil/air-cooled R1100GS.

Riding the GS

I’m riding Geoff May’s R100GS from 1993, one of the last years the big trailie was imported into North America.

At well over 500lbs with fuel and oil, and a seat height of 34.5 inches, this is a big, heavy motorcycle, and it takes some effort to roll it off the centerstand. The engine fires with the expected lurch to one side, then settles to a rocking idle. I take a refresher look at BMW’s unique handlebar controls — turn signal switches on both bars, and the “cancel” switch under the right grip — and snick into first gear.

Any Beemer (and especially the GS)  feels odd after a “regular” bike, but once rolling the GS is light and 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” in use.

With just 60bhp, it’s not fast, but the GS scores with its huge torque and broad, seamless 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 from the knobby tires is remarkable. They squirm under load but never seem to break away. I start to understand the appeal of the big brute. On bad tarmac, it would waltz around a regular sportbike.

Add great all-day comfort, simple low-tech maintenance and serious durability, and I can understand why, for many long-distance riders, the airhead GS “bumble bee” is still a top choice.

Owner’s View: BMW GS

Owner: Geoff May
Hometown: Surrey, BC, Canada
Occupation: Sales engineer
Bio: Originally from Zimbabwe, Geoff has been riding on- and off-road since his teens. He’s an Iron Butt Association member and has caught the long-distance riding bug. Other bikes include two Norton Commandos, Triumph Trident, Honda S65, Ariel Arrow and BMW K1200GT.
Etc.: A first-class wrencher and motorcycle restorer, Geoff has a local reputation for finding the most interesting and challenging roads in the Pacific Northwest.

Geoff bought his 1993 R100GS about a year ago with 60,000 miles on it. It needed work on the gearbox and drive shaft — the GS’s Achilles heel — but was otherwise in first-class shape. He mostly rides with his wife, Sue, on the passenger seat. “I wanted something that went on-road and off-road,” he says.

Geoff likes the GS’s easy handling, mechanical simplicity and straightforward maintenance. His main gripe: not enough horsepower. “It doesn’t have a lot of speed,” he says, “but what speed it does have, it’ll do all day. You just open the throttle and go.”

Fully loaded, the GS will cruise comfortably at 70mph, says Geoff, but above that, it feels unsteady. “Like a Norton Commando,” he says. Overall, Geoff says it’s a relaxing, easy bike to ride.
“It won’t overdo its limits: it doesn’t have enough horsepower!”

Does he plan to keep the bumble-bee? “Yes — until I get an R1200GS,” he jokes. MC