BMW adaptive aero springs into action: How pop-out bodywork is the future of aerodynamics

The idea of moving bodywork is far from new, but BMW are looking to get in on the act without the use of electronics. We’ve had electrically adjustable screens for years and more recently Moto Guzzi’s V100 Mandello added moving panels in the fairing, but now BMW have filed a patent for ‘adjustable air deflectors’ to boost comfort and improve aerodynamics.

The design is illustrated with the image of an R1250GS, but it’s clear the idea is applicable to most bikes.

The Mandello’s variable-position flaps, mounted between the rear edge of the nose fairing and the forward shoulders of the fuel tank, illustrate how adaptive aero can work, using electric servos to shift from their wind-cheating, flush position to an extended mode to push air away.

However, with servos and control electronics, they inevitably add weight and complexity.

BMW’s idea is to replace all that with something much, much simpler: springs. The deflectors are intended to be hinged at their front edges and sprung so they default into the extended position. Then, as you go faster and the air pressure increases, they gradually retract, eventually becoming flush with the surrounding bodywork to minimise drag at high speed.

The idea isn’t unlike some of the tricks that have been played in F1 car design in recent years, where manufacturers have employed wings that flex – giving maximum downforce when the cars are going slowly but tilting back to reduce drag as they go faster.

BMW’s patent explains that the system can be easily tweaked, as simply altering the stiffness of the springs on the air deflectors will alter how they’re deployed. They’d be tuned to fold away as speeds rise, remaining fully deployed up to around 30mph and becoming fully retracted by around 75mph.

When going slower than the lower threshold, the deflectors would be fully extended to push air away from the rider, improving comfort, and above the higher limit they’d be completely retracted to maximise efficiency.

In the design drawings, the bike is shown with three deflectors on each side, one mounted low down, another at mid height and the third relatively high on the fairing. Each could be tuned to retract separately with different strength springs and BMW’s patent is intentionally wide-ranging, as there’s virtually no limit to the shape, size or mounting position.

While the patent alone is far from confirmation that the idea is being developed to a production level, we know BMW are hard at work on a new generation of GS boxers incorporating new tech.

Prototypes were spied last year and in March this year BMW’s own service website accidentally included mention of ‘R1300GS’, ‘R1400GS’ and – most intriguingly of all – ‘M1300GS’ models, suggesting at least three variations are on the cards in the near future.