Active aerodynamics: the next big thing for superbikes

Ben Purvis_BikeSocial
By Ben Purvis

Writing about bikes for 20 years. Published in dozens of titles on five continents. Mildly obsessed with discovering how things work.

Clarified 2021 WSBK rules confirm moveable aero parts will be legal as long as they’re standard on the homologated road-going superbike

 

Regulation clarifications published by the FIM have confirmed that moveable aerodynamic parts are legal to use on WSBK race bikes provided that they don’t move more than they do on the production model they’re based on.

At first glance that might seem a redundant piece of legislation; after all, none of the superbikes that are currently homologated to run in the series have moving aerodynamic parts. But since we already know that both Honda and Aprilia have been working on active aerodynamics, confirmation of the idea’s legality at the top level of production-based racing means we’re almost certain to be offered road-going models with exactly that technology in the near future.

 

Clarified 2021 WSBK rules confirm moveable aero parts will be legal as long as they’re standard on the homologated road-going superbike

FIM rules decision opens the door to active-aero street bikes

 

Why does active aero matter so much? Because it offers vast advantages compared to the fixed winglets that are sprouting on many of the latest superbikes and every MotoGP machine.

The problems with those fixed wings are twofold. First, there’s the issue of drag. This is the element that active aerodynamics like those proposed by Honda address. At top speed in a straight line, the winglets offer little or no benefit in terms of stability and the downforce they create isn’t actually needed, but they carry a significant penalty in terms of drag – slowing the bike down.

The second problem is cornering. With fixed winglets, a proportion of the downward force they create turns into an undesirable sideways force once the bike is leaning into a corner. That force, far from helping the bike get around the bend, may try to fight against it, pushing the nose wide. Although we’ve yet to see any manufacturers try to solve this problem with active aero, it’s clear that the ability to move winglets – perhaps by altering their angle as a bike leans – could be a huge leap forward.

 

Clarified 2021 WSBK rules confirm moveable aero parts will be legal as long as they’re standard on the homologated road-going superbike

Honda’s active aero patent showed how winglets could extend from the sides

 

In Honda’s active aerodynamics patent, which we published back in September, the firm showed a bike very similar to the new, 2020 Fireblade but with the ability to withdraw its winglets into the bodywork when their downforce wasn’t needed. In doing so, it eliminated the drag penalty while keeping the ability to deploy the wings during braking, cornering or acceleration when their downforce might be helpful.

Aprilia hasn’t been so forthcoming about precisely how its idea for active aerodynamics works, but on last year’s RS660 concept bike the firm claimed it featured ‘Aprilia Active Aerodynamics’ or A3. Like the Honda system, whatever Aprilia’s design incorporated, it was largely hidden from view inside the fairing.

Just as Honda hasn’t opted to incorporate its active aero on the initial version of the all-new, 2020 Fireblade, the production derivative of the Aprilia RS660 also misses out on the concept’s moveable aerodynamics. It’s clear the firm has got just such a system in mind, though, and with a new RSV4 superbike expected for 2021, there’s got to be a strong chance that it will reappear on that machine.

 

Clarified 2021 WSBK rules confirm moveable aero parts will be legal as long as they’re standard on the homologated road-going superbike

Aprilia RS660 concept bike featured active aero, but it’s missing from the production version

 

The WSBK rule clarification states: For active or dynamic aerodynamic parts ONLY the standard homologated mechanism may be used. The range of movement must be the same as that used by the homologated road machine in normal use - not the mechanical maximum.

Those two sentences might well be instrumental in shaping a whole generation of road-going sports bikes. It’s clear that the FIM has made the decision not to ban moveable aerodynamics, and since it doesn’t want manufacturers to offer rudimentary systems on road bikes and then take liberties with more advanced systems on the track, and that bodes well for customers.

In the past, we haven’t seen any serious development on active aero because MotoGP squarely banned the idea several years ago. The GP rules cover it in just five words: Moving aerodynamic devices are prohibited.

Until recently even MotoGP bike designers believed that the cornering and drag drawbacks of wings would outweigh their advantages, so we’ve only seen the winglets emerge in the last few years. There’s an understandable delay in getting the same tech to road bikes, and no doubt many bike firms have assumed that WSBK rules would take the same ‘no moving parts’ stance as MotoGP.

 

Clarified 2021 WSBK rules confirm moveable aero parts will be legal as long as they’re standard on the homologated road-going superbike

Airbrakes are already used on supercars – could they appear on superbikes next?

 

Far from banning the idea, the clarification opens the door to far wider exploitation of the possibilities. After all, downforce is only one element of movable aerodynamics.

When wings first started appearing on racing cars in the 1960s designers instantly jumped on the potential of moving parts, creating systems to flatten wings on straights and spring them back into place during corners. That was soon banned after a few accidents when wings failed to come back into their downforce-creating position, but in recent years the idea was reintroduced as F1’s controversial DRS (drag reduction system) to give drivers a better chance at overtaking the vehicle ahead.

Even earlier, in the 1950s, moveable aero was successfully used on racing cars. Not for downforce, but in the form of airbrakes; already well established tech from aircraft design. The Mercedes’ 1955 300 SLR Le Mans car, for instance, used a flip-up section of bodywork behind the driver’s head to help slow it down and give the brakes an easier life. Many modern road-going supercars from the likes of McLaren and Bugatti also feature moving wings that turn into airbrakes when their drivers slam on the anchors. While we have yet to see a superbike that tries the same thing, it’s sure to be under consideration.

It’s only natural that as you read this, superbike designers around the world are looking at every implication of the FIM’s WSBK regulation clarification and working out precisely how they can use active aero to their advantage in the future. This might well be the next big arms race for sports bike firms, and customers should be the winners in the end.

 

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