A recent patent filing by BMW suggests it's bringing back a cruiser for the first time in over 10 years. But the engineers at Motorrad apparently aren't content with sticking with its tried-and-true boxer, so the plan – at least on paper – is to attempt to cram a third cylinder into the classic, air-cooled v-twin configuration. Because Germans.
BMW cancelled the boxer-powered R1200C after the measly 61 hp twin was deemed unsuitable for the current market. Since then, BMW has given up on the cruiser segment, opting to hock the GS line to those looking for a comfortable, tech-laden two-wheeler. But BMW is looking to expand, and a cruiser is the next obvious hole to fill after a new middle-weight.
Naturally, it's not content with the status quo. So while a V-twin would make a plausible alternative powerplant, BMW doesn't have one on the shelf and, anyway, it's played out. Instead they're doing the most German thing possible: using over-engineering to make a statement.
Granted, this isn't the first time a W3 engine has been considered. BMW's own patent documentation references the Feuling W3, a design originally developed by Harley-Davidson.
The major disadvantage to the Feuling W3 was its 90º angle between the first and third cylinders requires a large amount of space to make everything fit. Moto Guzzi also made a prototype W3 engine in 1982. The W103 was designed to run longitudinally, with the first and third cylinder sticking out the sides in typically freakish Moto Guzzi fashion.
The BMW layouts show a total of 65 to 75 degrees. That's much closer to a conventional V-twin dimensions, meaning it could follow traditional styling cues despite the extra cylinder.
Patents for two separate three cylinder designs have been filed with similar form but a few distinct features. In the first, each cylinder has its own designated crankpin, more like an inline-triple where a single crankpin would not be shared by more than one piston. This results in a wider layout while allowing any firing order and retaining the classic cruiser look.
The second patent is a bit stranger, with the front and rear cylinders sharing a crankpin, as per a normal V-twin engine, while the vertical middle cylinder is attached to a separate crankpin that's offset around 90 degrees from the first.
But the biggest – and most shocking – element of the patent is the use of pushrods. That might turn off most BMW purists, but the simplified design, size advantage, and aesthetics could be a boon to cruiser buyers looking for something new. Then again, it's just a patent, and that means it might just be an engineering exercise for the boffins at BMW and may never see the light of day.