It began, as good engineering often does, with a complaint. In 1922 the Treaty of Versailles had forbidden Germany from building aircraft engines, and BMW — a company that until then had made almost nothing else — was reduced to air brakes, farm machinery and office furniture. When Franz Josef Popp asked his design director to assess the Helios, a motorcycle the firm had inherited through merger, Max Friz reported back that the best thing to do with it was throw it in the nearest lake. Its engine sat with the crankshaft fore and aft, and the rear cylinder cooked itself in the shadow of the front one.
Friz's answer was not to improve the cooling. It was to turn the engine sideways so that both cylinders stood out in the airstream, where nothing could hide from the wind, and to run the drive straight back through a shaft rather than a chain. The R32 that resulted in 1923 made 8.5 horsepower from 494 cc and would do about sixty miles an hour. Only three thousand or so were built. But the shape of it — a flat twin with its heads in the breeze and a driveshaft down the right side — is still the shape of a BMW boxer a century later. Very few design decisions survive their designer. This one survived the century.
The engine in your workshop is a direct descendant, and it arrived with a change of address. Through the sixties, car production in Munich swelled until the motorcycles had to go somewhere else; in 1969 BMW finished moving the whole operation to Berlin-Spandau, into a plant Siemens had built for aero engines in 1928 and BMW had owned since 1939, when it made nine-cylinder radials for the Ju 52. The move had been coming for years — Spandau had supplied parts since 1949 and frames since 1958, and the first complete Berlin-built BMW, an R60/2, was finished on 6 September 1966 — but 1969 was the year the engine shop followed: four hundred people, thirty motorcycles a day, all of it by hand. What came out of it that year was the /5 — the R50/5, R60/5 and R75/5 — an entirely new machine built on a modular principle from the suspension to the flat twin itself. It sold. Production ran five-fold in three years, and by the time the /5 ended in July 1973 nearly sixty-nine thousand had left the line.
Then the decade the platform is remembered for. In 1973 the engine grew for the first time and gave us the R90/6 and the R90S, that smoked-orange half-faired thing that made touring bikes look fast. The /6 of 1974 brought a front disc and the five-speed box. In 1976 the R100RS arrived as the first production motorcycle in the world to wear a full frame-mounted fairing, developed in a wind tunnel, and the R45 and R65 filled in beneath it from 1978, on a shorter frame of their own. The hundred-thousandth Berlin-built machine had left the line in January 1975; the quarter-millionth followed in 1980, built for the escort of King Hussein of Jordan. This is the high-water mark of the airhead: the range at its widest, the engineering at its most confident.
And in 1980, almost as an afterthought, the machine that outlived all of them. The R80 G/S went from go-ahead to showroom in twenty-one months, carried BMW's first single-sided swingarm, the Monolever, and on paper it was absurd — a 797 cc shaft-drive twin weighing four hundred pounds, entered into a sport where everyone else rode light singles. In 1981 Hubert Auriol took it to overall victory in the Paris–Dakar, the first time anything but a single-cylinder machine had won it. He won again in 1983; Gaston Rahier, all five foot four or so of him, won in 1984 and 1985. The photographs of that enormous tank and those cylinder heads jutting into the Sahara did more for the boxer than any brochure ever printed, and every adventure bike sold since owes it a debt.
The end came slowly, and from inside the family. The water-cooled K100 landed in 1983 and BMW let it be known that the big boxer was finished: the 1984 R100RS was sold as a farewell, five hundred “Classic 500” machines in Germany and a “Last Edition” in America. The customers declined to accept this. The RS was back on the stand at Cologne in 1986, meant as a thousand-off special, and stayed in production until 1992. In 1993 — seventy years after the R32 — the R1100RS introduced a boxer with oil cooling and four valves per head, and the word airhead, which an American owners' club had coined for itself two years earlier, became a retronym for what had just been superseded. The R100R and its Mystic variant ran to 1996, but the very last of them was not a road bike at all: an R80GS Basic, the final one of 3,003 built in homage to the original G/S, came off the Spandau line in December 1996. Then the line that Max Friz drew in December 1922 finally stopped moving.
Which brings us to the bench. What you have is not a vintage motorcycle in the fragile sense — it is a mature industrial design that was refined for seventy years and then discontinued while it was still good. The tolerances in this book are wide because the engine was built to be serviced by hand, at the roadside, by someone who owned a feeler gauge and a decent memory. Nothing on it is hidden. Nothing on it requires a laptop. It will tell you what is wrong if you know how to ask, and everything after this chapter is a way of asking.
Every figure on this page resolves to one model and year in the book. Pick your bike and the rows that apply to it come forward, with the rest marked.
Open this chapter in the book| Year | Event | Why it matters | Notes | |
|---|---|---|---|---|
| 1923 | R32 | 494 cc · 8.5 hp @ 3200 rpm | the layout is born | Max Friz turns the engine transverse so both cylinders sit in the airstream, and adds shaft drive. 3,090 built through 1926. Every boxer since is this drawing. |
| 1969 | /5 — R50/5, R60/5, R75/5 | Munich → Berlin-Spandau | the modern airhead begins | All-new modular design in a former Siemens aero-engine plant. 68,956 built to July 1973. |
| 1973 | R90/6 & R90S | first displacement increase | the range grows up | The R90S gave the boxer a sporting reputation it had not had before. |
| 1974 | /6 series | front disc · 5-speed | brakes and gears | Early disc used a hybrid cable-to-master-cylinder linkage. Rectangular tank dropped. |
| 1976 | R100RS · /7 series | 980 cc | the platform peaks | First volume-production motorcycle in the world with a full frame-mounted fairing. R100, R100S, R100RS, R75/7, R60/7. |
| 1978 | R45 & R65 · R100RT | the small frame · the touring fairing | widest range | A shorter chassis for the small twins; the RT put a touring screen on the RS idea. The hundred-thousandth Berlin bike had already left the line in January 1975. |
| autumn 1980 | the great changeover | new crankcases · Galnikal bores · electronic ignition from '81 | the parts watershed | The single most important date for ordering parts. Ask “before or after 9/80”, never the model year — see Spec Boundaries. |
| 1980 | R80 G/S | 797 cc · Monolever | the ancestor of every adventure bike | BMW's first single-sided swingarm, the Monolever. Shown to the press at Avignon on 1 September 1980; 6,631 sold in 1981, one BMW in five. |
| 1981–85 | Paris–Dakar | Auriol '81 & '83 · Rahier '84 & '85 | proof | Auriol's 1981 win was the first for anything but a single. Only that bike was an 800; the later winners were 980–1,043 cc works specials built by Herbert Schek and then HPN. |
| 1983 | K100 | water-cooled four | the succession starts | The airhead is no longer the future of the company. |
| 1984 | R80 & R80RT Monolever | and the “last” R100RS | the farewell that wasn't | The single-sided swingarm reaches the road bikes. Five hundred Classic 500s in Germany and a Last Edition in America were meant to close the big boxer; the customers refused. |
| 1985–87 | the boxer stays | R65 Monolever '85 · R100RS back '86 · R100RT '87 | late refinement | The RS returned at Cologne in 1986, planned as a thousand-off special, and ran to 1992. |
| 1987 | R80GS & R100GS | Paralever · cross-spoke wheels | the shaft-drive lurch is cured | A double-jointed swingarm with a torque strut. Over 45,000 sold by 1996; the Paris-Dakar version followed in 1989. |
| 1991 | R100R · the millionth BMW | 18 March 1991 | a roadster, and a milestone | The GS turned back into a road bike. The same spring the millionth BMW motorcycle since 1923 — a K75RT — left Spandau. |
| 1993 | R1100RS — the oilhead | 1085 cc · 4 valves · oil-cooled | the word sticks | Seventy years after the R32. “Airhead”, two years old, becomes a retronym for what came before. |
| Dec 1996 | R80GS Basic | 3,003 built · the last two-valve boxer | end of the line | The R100R and Mystic ran to 1996; the last airhead of all was a GS. Seventy-three years after Friz finished his drawings. |
Forty-six years of boxers came before the first airhead. Most of what you will touch on the bench was settled in them.
The R32 was a side-valve engine, and it stayed that way for two years. In 1925 Rudolf Schleicher put overhead valves and the first light-alloy cylinder heads on any motorcycle onto the R37, doubled the power to 16 hp, and BMW won every German 500 cc championship from 1924 to 1929 with it. Then the frames started cracking. Sidecars were how Germany travelled, and a brazed tube frame with a heavy chair hung off it broke at the steering head; BMW's answer, from 1929, was the pressed-steel frame of the R11 and R16 — heavy, plain and very hard to break.
The bike that looks like yours is the R5 of 1936: a tubular double-cradle frame welded electrically under shielding gas, a hydraulically damped telescopic fork, a foot-change four-speed gearbox and a 494 cc engine with two chain-driven camshafts. Schleicher called it his most important design. Only 2,652 were built before the R51 added plunger rear suspension in 1938 and the war ended the argument. The war's own boxer, the R75 sidecar outfit, drove its sidecar wheel through a locking differential, carried a reverse gear and a set of off-road ratios, and ran 5.8:1 compression so that it would live on whatever the army called petrol. Between 16,500 and 18,000 were built, the last of them at Eisenach after Munich was turned over to aero engines in October 1942.
In October 1945 the American military government ordered the Munich works dismantled. Eisenach was in the Soviet zone and went on building the pre-war R35 under the BMW badge until a court made it change the name to EMW. Munich made pots, pans and farm tools, was allowed nothing over 250 cc, and came back in December 1948 with a single, the R24 — 9,144 of them sold in 1949 alone. The first post-war twin was the R51/2 of 1950, five thousand in a year, followed by the 600 cc R67 and then the R68: 35 hp, 160 km/h, announced at Frankfurt in 1951 as the “100 Mile Racer”, the first German production motorcycle that would do a hundred miles an hour.
The Earles-fork era began in 1955 with the R50 and R69: swinging arms at both ends, the driveshaft running inside the right-hand rear arm, a chassis designed around the sidecar and adopted by police forces the world over. It was the wrong moment. German motorcycle sales collapsed from thirty thousand a year to under six thousand, and on 9 December 1959 BMW's shareholders sat through a ten-hour meeting at which a time-limited offer from Daimler-Benz to absorb the company was fought off by the small shareholders; Herbert Quandt bought in afterwards, and the BMW 700 car paid the bills. The R69S was launched into the middle of that — 42 hp, 175 km/h, the fastest German production machine of its day and the first BMW you could buy in white, a colour until then reserved for the authorities. 69,289 of the Earles-fork twins were built over fourteen years. The last of them, the US models of 1968–69, went out on telescopic forks developed for the factory's Six Days team, fitted at the insistence of the American importer. That is how the bridge to the /5 was built: from the customers' side.
| Year | Event | Why it matters | Notes | |
|---|---|---|---|---|
| 1925 | R37 | 494 cc OHV · 16 hp | the first alloy heads | Rudolf Schleicher's engine, raced in 1924 and sold from 1925. Every German 500 title from 1924 to 1929. |
| 1929 | R11 & R16 | pressed-steel frames | built for the sidecar | Brazed tube frames cracked at the steering head under sidecar loads. Five series to 1934; the R16 won the 1933 Six Days in Wales. |
| Sept 1929 | Ernst Henne | 216 km/h · 750 cc supercharged | the fastest man on two wheels | Eight world records in a day, on the road north of Munich. He finished in November 1937 at 279 km/h in the fully enclosed “egg”, a record that stood until 1951. Seventy-six records in all. |
| 1936 | R5 | welded tube frame · telescopic fork · foot change | the grandfather | Schleicher's “most important design”. 2,652 built; the R51 of 1938 added plunger rear suspension. |
| June 1939 | Senior TT | Georg Meier · Type 255 Kompressor | first non-British winner | A 492 cc supercharged boxer, 60 hp, 138 kg. Jock West second on the other one, two minutes back. 89.38 mph, a race record. |
| 1941–44 | R75 | 745 cc · driven sidecar wheel | the war machine | Locking differential, reverse, off-road ratios, 5.8:1 for bad fuel. 16,500–18,000 built, depending on who is counting. |
| Oct 1945 | dismantled | Munich and Allach stripped as reparations | year zero | Eisenach lost to the Soviet zone. No control of its own assets until 1949, and nothing over 250 cc allowed. |
| Dec 1948 | R24 | 247 cc single · 12 hp | the restart | 9,144 sold in 1949 alone; 12,020 in all. |
| 1950 | R51/2 | 494 cc · 24 hp | the twin returns | The pre-war R51 revived, with two-piece valve covers held by a clip. Five thousand in one year. |
| 1952 | R68 | 594 cc · 35 hp · 160 km/h | the hundred-mile-an-hour BMW | Announced at Frankfurt in 1951 as the “100 Mile Racer”. Narrow front guard, optional high-level two-into-one. |
| 1954 | sidecar world title | Noll & Cron · RS54 | the start of twenty years | BMW outfits took 19 riders' world titles between 1954 and 1974. Klaus Enders won the last of them, in 1974, by two points on an engine everyone agreed was at the end of its development. |
| 1955 | R50 & R69 | Earles fork · swinging-arm rear | the /2 chassis | Driveshaft inside the right arm. Police forces everywhere. |
| 9 Dec 1959 | the ten-hour meeting | Daimler-Benz refused | survival | Small shareholders blocked the takeover; Herbert Quandt bought in; the 700 car paid the bills. Motorcycle output stayed small until Berlin. |
| 1960 | R69S | 594 cc · 42 hp · 175 km/h | the fastest German bike | Eleven thousand-odd built to 1969. The first BMW offered in white. |
| 6 Sept 1966 | first Berlin-built BMW | an R60/2 | the move begins | Frames from Spandau since 1958; final assembly from 1966; engines from 1969. |
| 1968 | US models | telescopic forks | the bridge | Forks from the Six Days team, at the American importer's insistence. About a thousand R69US were built. |
| Who | When | What they gave you | Notes | |
|---|---|---|---|---|
| Max Friz | 1922 | aero-engine designer | the layout | Told to assess the fore-and-aft Helios, said to throw it in the lake, and drew the R32 in weeks: transverse twin, shaft drive, both heads in the wind. |
| Rudolf Schleicher | 1925 · 1936 | engineer and rider | overhead valves · the R5 | Alloy heads on the R37; the frame, fork and gearbox of the R5. Raced and won on his own work. |
| Ernst Henne | 1929–37 | record rider | the records | Seventy-six of them. Rode the supercharged egg to 279 km/h in November 1937 and then stopped, undefeated. |
| Helmut Werner Bönsch | 1963 | technical director | the decision to stay | Committed BMW to motorcycles when the board wavered — “even if we have to make the last machine out of pure gold”. |
| Hans-Günther von der Marwitz | 1964–69 | from Porsche | the /5 | Recruited in 1964 to reinvent the boxer. The Type 246 frame, the telescopic fork and the modular engine of the /5 are his. |
| Hans A. Muth | 1973–81 | from Ford car interiors | how it looks | The R90S paint and cockpit, the R100RS fairing, the R65LS, and the G/S concept, sketched in twenty minutes after a look at a Range Rover. Later, Suzuki's Katana. |
| Laszlo Peres | 1977–79 | test engineer | the GS 800 | Built a 124 kg, 800 cc boxer enduro on his own initiative and was runner-up in the 1978 German championship on it. |
| Rüdiger Gutsche | 1979–80 | development chief | the Monolever | Ran the G/S project and designed its single-sided swingarm. |
| Karl-Heinz Gerlinger | 1979 | the new boss | the go-ahead | Arrived in early 1979 with orders to save the motorcycle division or shut it. Chose the G/S, and within two years it was on sale. |
| Herbert Schek · HPN | 1983–86 | the Dakar shops | the desert bikes | Schek, fourteen times German off-road champion, built the 1983 and 1984 winners and rode one himself at forty-nine. Halbfeld, Pepperl and Neher built the later works machines and most of the good private ones since. |
The first AMA Superbike race ever run was won by an R90S. So was second place.
Butler & Smith of New Jersey had held the American import franchise since February 1954, and for 1976 they went racing with three R90S and a chief mechanic, Udo Gietl, who had already been building BMW racers for the Formula 750 class. His engines revved to ten thousand where the factory had designed for six. Titanium connecting rods, hollow lifters, a monoshock rear end by Todd Schuster, chainsaw reed valves to breathe the crankcase, oil separators borrowed from a Chrysler Hemi: roughly a hundred horsepower from a motorcycle that left Spandau with sixty.
Gary Fisher led until his gearbox failed. Steve McLaughlin and Reg Pridmore crossed the line together, and the commentator, Roxy Rockwood, called it for Pridmore. The photograph said McLaughlin, by about three inches. Pridmore went on to take the first AMA Superbike championship that year, the team finished first, second and third in the points, and Butler & Smith then withdrew from Superbike racing because it cost too much. McLaughlin, for his part, later founded the World Superbike championship. The three bikes were reunited at Daytona in March 2026, fifty years on.
The boxer's two TT wins came thirty-seven years apart. One of them was on a road bike.
On 16 June 1939 Georg “Schorsch” Meier won the Senior TT on the supercharged Type 255 — a 492 cc flat twin with twin overhead camshafts, a Zoller blower, 60 hp and a dry weight of 138 kg — at a record 89.38 mph, with Jock West second on the other works machine two minutes behind. He was the first rider from outside Britain to win the Senior since the race began in 1907. The same machine, hidden through the war, won him German championships in 1948, 1949 and 1950.
In 1976 Helmut Dähne and Hans-Otto Butenuth rode a Daytona Orange R90S, some thirty kilograms lighter than stock, to the 1000 cc class win in the ten-lap Production TT. Theirs was the fastest time of the entire race — 98.92 mph over more than six hundred kilometres — though the class handicap placed them fifth overall, and it came after Dähne borrowed a spare cylinder head from a rival BMW entrant mid-meeting. Two years earlier he had been third on a near-standard R75/5 fitted with an R90S engine. Dähne rode twenty-six TTs between 1972 and 1994, and his 1993 lap of the Nürburgring Nordschleife — 7 min 49.71 s — is still spoken of as the motorcycle record there.
| Model | Built | Who says | Notes | |
|---|---|---|---|---|
| R32 | 3,090 | 1923–26 | BMW | About sixty are thought to survive. |
| Earles-fork twins | 69,289 | 1955–69 | BMW | R50, R60, R69 and their /2 and S versions together. |
| /5 | 68,956 | 1969–July 1973 | BMW | 12,287 in 1970, the first full Berlin year. More than 38,000 were R75/5s; fewer than 8,000 R50/5s. |
| R90S | 17,465 | 1973–76 | BMW Classic | Falloon says 17,455. Either way, about seventeen and a half thousand. |
| R45 · R65 · R65LS | 28,158 · 29,454 · 6,389 | 1978–85 | Airheads Beemer Club | Club figures, not BMW's. The R65 continued on the Monolever frame to 1993. |
| R80 G/S | 21,864 | 1980–July 1987 | BMW | 6,631 in the first year. Almost 3,000 of them were the 800 cc Paris-Dakar version. |
| R80GS & R100GS | over 45,000 | 1987–96 | BMW | R100GS alone 34,007; R80GS 11,375. The R65GS, 1,727. |
| R80GS Basic | 3,003 | 1996 | BMW Classic | The last two-valve boxer, December 1996. |
| Berlin milestones | 100,000th · Jan 1975 | 250,000th · 1980 | BMW | The millionth BMW motorcycle of all, a K75RT, on 18 March 1991. Spandau's first fifty-thousand year was 1995 — the year before the airhead ended. |
Twenty-three years old, a 1974 R60/6 with 45,000 miles already on it, and a letter from BMW politely declining to help.
She had asked around for sponsorship before she left, the way you were supposed to. Most of the manufacturers and magazines did not reply at all. BMW in Munich did — a courteous letter explaining that they would not be supporting her ride around the world. She kept it. It is reproduced in her book, which is a quieter form of revenge than most people manage.
What she did instead is the part that belongs in a workshop manual. She bought a Haynes manual and stripped the engine down to understand it. She replaced every cable, fitted a new battery, changed all the oils, put new tyres on a motorcycle that had already covered forty-five thousand miles. And then she took the cylinder heads off and fitted an extra base gasket, deliberately lowering the compression, because she had worked out that the fuel between London and Sydney was not going to resemble the fuel in Surrey.
That is a decision from the Finishes and Upgrades chapters of this book, taken in a garage in 1982, by someone who had reasoned it out from first principles rather than read it anywhere.
She rode out in October 1982 with no sponsors, no GPS, no mobile telephone and just enough money to cross the Atlantic. Thirty-five thousand miles followed: north into Canada, south to Mexico, the bike shipped to New Zealand and then Australia, where she crashed it. Hepatitis caught up with her in Iran. She forged permits in India. She came home to London in November 1984, one of the first British women to have ridden a motorcycle around the world alone, and then quietly went back to finishing her architecture degree.
In 1988 she bought a derelict hundred-and-thirty-foot Victorian water tower and spent seven years turning it into a house, which went on to win five architectural awards. The R60/6 is still in the garage underneath it — restored, not on a plinth, parked between a 1973 R75/5 and the R80 GS Basic she still rides most days.
A quarter of a million miles, seventy-seven countries, and one stretch of jungle that took three weeks to cross.
He left Kristiansand in 1982 on an R80 G/S with loose plans and a tight budget, which is how most of these stories start and not how most of them continue. The trip lasted ten years. By the end the motorcycle — he called it Olga — had covered more than two hundred and fifty thousand miles through seventy-seven countries, which is roughly ten times around the earth on an air-cooled twin designed in the 1960s.
Ask him which part mattered most and the answer is not a country. It is sixty-six miles: the Darién Gap, the roadless swamp and forest between Colombia and Panama where the Pan-American Highway simply stops. There is no route through it. There was no route through it then either. With the help of a German backpacker he had picked up along the way, Pedersen spent twenty days wrestling a four-hundred-pound shaft-drive BMW across rivers and through jungle that had no interest in either of them.
Olga now sits in the BMW Museum in Munich — which is a fair resting place for a motorcycle that went a quarter of a million miles on the strength of the numbers in this book.
He has been leading rides ever since, out of Seattle, and has taken groups to Tierra del Fuego more times than most people ride to the next state.
A retired army officer, a 1981 R80 G/S, and the sixty-odd miles the Pan-American Highway never finished.
Culberson had served in the Panama Canal Zone and knew exactly what the Darién was. He set out anyway to ride the Pan-American Highway entire, from Alaska to Tierra del Fuego with no ship in the middle, on a G/S he called Amigo. The first attempt, in 1985, lasted thirty-three days and got as far as the village of Pucuru before the jungle won. He went back in 1986 and got through — the motorcycle ridden where it could be, dragged, floated and carried where it could not — and became the first motorcyclist to complete the whole Highway including the Gap.
He wrote it up as Obsessions Die Hard, published in 1996, the year after motor neurone disease killed him. Amigo spent twenty-four years on display at the BMW Zentrum in South Carolina before going home to Florida in 2018, and Aerostich named a jacket after the crossing.
Everyone knew the Dakar belonged to light singles. Nobody had told BMW.
In 1981 Hubert Auriol took an R80 G/S to overall victory in the Paris–Dakar, the first time anything but a single-cylinder machine had won the event. On paper the thing made no sense at all: a shaft-driven boxer weighing four hundred pounds, entered against nimble singles, in a rally that was then closer to an expedition than a sport — compass and roadbook, and terrain that punished machine and rider equally.
He did it again in 1983. Then Gaston Rahier, who stood five foot four and by most accounts could not get both feet down, won it in 1984 and again in 1985. The photographs from those years — that enormous tank, those cylinder heads jutting out into the Sahara — did more for the boxer than any advertisement BMW ever paid for, and every adventure motorcycle sold since owes them something.