Helios
An Aircraft Factory Runs Out of Airplanes
Picture Munich in 1919. The war is over, the Treaty of Versailles has just forbidden Germany from building military aircraft, and a company called Bayerische Flugzeugwerke — BFW for short — is sitting on a factory floor built to turn out warplanes at a rate of more than 200 a month, with some 3,000 people on the payroll who need something to build. That is the room Helios was born into. It was never a passion project dreamed up by a garage tinkerer with a name and a vision; it was a stopgap, a way for an aircraft manufacturer to keep its machinists employed and its lathes turning while the world decided whether it would ever be allowed to build airplanes again.
BFW's answer, from 1921 onward, was to put its name on two motorcycle lines: a small machine called Flink, and the one that concerns us here, Helios. Neither carried the personal stamp of a founder-engineer in the way so many marques of the era did. Helios was a factory product from a factory that used to build fighters, and it shows in almost everything about the bike's short life.
The Machine Itself
The Helios motorcycle was designed by an engineer named Karl Rühmer, and it used a 492cc flat-twin engine, the BMW M2B15, mounted longitudinally in the frame — the cylinders sticking out on either side like a Douglas, rather than across the frame the way BMW twins would soon become famous for. It's worth being precise about where credit belongs here, because the history gets tangled: the M2B15 engine itself was not Rühmer's work. It had been designed at BMW by Max Friz and developed by Martin Stolle, and Rühmer's contribution was the motorcycle built around that engine — the chassis, the layout, the machine that carried the Helios name. Two different jobs, two different men, and later accounts have a habit of blurring them into one.
The longitudinal layout was the design's fundamental problem. With the cylinders arranged fore-and-aft along the frame rather than across it, the rear cylinder sat tucked in behind the front one, starved of clean airflow. On a machine meant to be ridden hard and for distance, that is not a footnote — it is the kind of flaw that cooks an engine. BFW built the Helios this way through 1921 and 1922, a modest run by a company that was, at heart, still hoping the aviation ban would lift and it could go back to what it actually knew how to do.
The Merger, and a Verdict Involving a Lake
In 1922, BMW — at the time primarily an engine manufacturer, having supplied the M2B15 to BFW and others — merged with Bayerische Flugzeugwerke. Suddenly the Helios, flaws and all, was BMW's problem. General Director Franz Josef Popp handed the motorcycle to his design director, Max Friz, and asked him to assess it.
Friz's verdict has survived because it is one of the great blunt assessments in motorcycling history: he told Popp that the best thing to do with the Helios would be to take it out and dump it in the nearest lake. His specific objection was the transverse-crankshaft, Douglas-style layout and the way it strangled cooling to the rear cylinder — precisely the weakness built into Rühmer's original design. This was not a case of an engineer politely suggesting refinements. Friz was telling his employer the thing didn't work and shouldn't be patched.
What happened next is often told as a tidy story of improvement — Friz supposedly taking the Helios and fixing it into something better. The truth is less linear and more interesting. Friz didn't improve the Helios; he threw out its premise entirely. Rather than reworking the longitudinal engine, he designed a new motorcycle from scratch around a transverse flat-twin — cylinders sticking out into the airflow on either side, both cooled properly, drive running back through a shaft rather than a chain. That machine became the BMW R32, released in 1923. Martin Stolle, for his part, joined BMW in 1923 after previously working at Victoria, and he would go on to develop OHV transverse twins for the company in the years that followed — but exactly what part, if any, he played in the R32's original design is not something the sources settle one way or the other. It's safer to credit him with shaping BMW's twin-cylinder engineering afterward than to name him as co-creator of the R32 alongside Friz.
BMW did keep building Helios motorcycles for a short stretch after the merger — production continued into 1923 before the line was shut down that November, by which point the R32 had already made the old design obsolete. Helios wasn't refined into BMW's first motorcycle. It was assessed, condemned, and quietly retired while something better took shape beside it.
No Golden Era, and Racing That May or May Not Have Happened
Any honest account of Helios has to resist the urge to dress the story up. There was no golden era. Helios was in production for roughly two years, built by a company that had bigger problems than motorcycle sales, using an engine layout that its own eventual parent company's chief engineer wanted thrown in a lake. It was a commercial failure by the standard of what came immediately after it.
On the question of racing, the honest answer is that nothing turns up in the available record — no results, no known entries, no rider names attached to a Helios in competition. That absence is worth stating carefully rather than flatly, and it would be a mistake to treat it as proof of anything. Records from small manufacturers of the early 1920s are spotty at best, and a gap in what turns up today does not mean a gap in what actually happened. The lack of documented racing history could simply reflect how little documentation survives from a two-year production run by a company in the middle of a corporate merger, rather than evidence that no Helios ever lined up at a start line. Given how thin the surviving paper trail is on Helios generally, the honest label here is unverified rather than settled — an open question nobody has yet answered, not a closed one.
What Helios Actually Left Behind
The Helios matters for exactly one reason, and it's not subtle: its shortcomings gave Max Friz a reason to design something else. Trying to make sense of why a company would inherit a flawed motorcycle and respond by tearing up its entire architecture, you land on the obvious explanation — Friz looked at the cooling problems built into that longitudinal twin and decided the fix wasn't a fix at all, but a different motorcycle. The R32's transverse twin, its shaft final drive, the whole layout that BMW would carry forward for the better part of a century in one form or another, exists in part because Helios demonstrated so clearly what didn't work.
That makes Helios a stepping stone rather than an achievement, and there's no point pretending otherwise. It isn't remembered for a landmark model, a celebrated engine, or a moment of racing glory. It's remembered because BMW's own official telling of its motorcycle origins routinely stops at Helios on the way to the R32, using it as the cautionary example that explains why the R32 looked the way it did.
After BFW, After Helios
Bayerische Flugzeugwerke's own story continued well past the point where Helios stopped mattering to it. The company split off from BMW again in 1926 and returned to aviation, which had been the point all along. In 1927 it was joined by a young engineer named Willy Messerschmitt, and in July 1938 the company was renamed Messerschmitt AG — a name that would go on to mean a great deal more to the twentieth century than any motorcycle ever built under the BFW banner. The motorcycle interlude, Helios included, was a brief detour for a business that ultimately found its way back to airplanes.
Helios itself never got a second act. There was no independent revival, no small workshop keeping the name alive decades later, no retro-badged tribute built by a modern owner chasing nostalgia. BMW absorbed what mattered — the lesson, not the machine — and moved on to the R32, which is the bike people actually wanted to ride and the one that built BMW's reputation in the twenties and beyond.
Where Helios Sits Today
Helios motorcycles have not been in production for a century, and nothing about that is likely to change. What survives exists in museum collections and specialist archives — the sort of place where a longitudinal flat-twin from 1921 gets wheeled out as an artifact rather than ridden as transportation. Institutions like the PS.SPEICHER museum hold the kind of material that keeps the Helios story from disappearing entirely, even if it's a story told mostly in service of explaining something else.
For collectors, that scarcity cuts one way: what little survives is rare, and rarity has its own market logic regardless of how the bike actually performed. A working Helios, or even solid period photographs and documentation of one, holds real interest for the small circle of people who study BMW's origins closely. But nobody is buying a Helios because it was a great motorcycle. They're buying it, or studying it, because it's the answer to the question of what BMW was trying to get away from when Max Friz sat down and designed the R32. That's a strange kind of legacy — being remembered chiefly as the mistake that pointed the way forward — but it's the one Helios actually earned, and there's no need to gild it further.