Motorcycle winglets - how do they work?

Welcome to our Home Schooling series. The idea is to present motorcycling technology in a simple form everyone can understand, even children. If you’re a British Superbike technician or a professional rider, stop reading and go make a brew. For the rest of us, pin your ears back, get a note pad and pen and read on. Unlike school, there won’t be any homework, there isn’t a test at the end and because you’re at home nobody knows if you’re picking your nose or eating your lunch early. Now concentrate on today’s lesson...

Why do motorcycles have wings?

From controlling the motorcycles stability to aiding braking performance, we look at why motorcycles have wings

Lesson 2 – Why do motorcycles have wings?

We now have a basic understanding of aerodynamics (see above), and how that affects you and your motorcycle. Larger surface areas are bad, a small surface area is good. Now we are going to take it to the next stage and look at aerodynamic wings which are increasing in popularity. Again, it’s not as complicated as you might think. After this article, you’ll be to explain aerodynamic wings to your children, or your mates down the pub/café.

Aeroplanes:  When man wanted to fly, he only had a little engine and therefore needed huge wings to create the lift needed for flight. Today, a fighter jet can use smaller wings as it has an excess of power and thrust. And while wings on a motorcycle create downforce, the opposite of lift, they work in a similar way.

Huge wings for bikes: In theory, the best solution to creating downforce on a motorcycle would be to add huge wings. However, we can’t do that because large wings would poke pedestrians, you wouldn’t be able to filter in traffic, and they’d hit the road or track when you leant over. Not good. Therefore, on a bike, we are restricted by where we can add wings and the size they can be. But we can use historical aviation for inspiration. The bi-plane creates a similar lift to a plane with a large wingspan, but the wings are shorter. We see a similar design on bikes today, with multiple short wings.

So, what do the wings do? The wings create downforce onto the motorcycle. But even though the wings are towards the front of the bike, downforce isn’t just going down the fork legs to the front wheel. The main area of downforce is created around the engine, towards the front but more centrally. There is also a small percentage of downforce towards the middle and even the rear of the motorcycle.

Wings are not always working: A plane can’t take off without moving, it must have wind moving over the wing to create lift, and it is the same principle for wings on a motorcycle. At low speeds the wings are doing nothing aside from looking good; it’s only when speed increases that they start to take effect. This depends on the style and shape of the wing, but usually they only start working from 60mhp upwards. Then as speed increases so does downforce. At high speeds 180mph, the wings can create 30-50kg of downforce, which is like having a large dog sitting on the bike with you.

What are the advantages of creating downforce with wings? On a powerful sports bike, the wings reduce the number of wheelies, either on the power or as you ride over crests and humps (think of the Isle of Man). Even above 60mph when the wings start to work, big powerful bikes will still want to wheelie, and the only ways to control that is by reducing the power manually, electronically (rider aids), or moving the rider forward. Now we can accelerate harder with less fear of wheelies as the wings are creating downforce. This is the same for undulations which cause high-speed wheelies, think of tracks like Portimao, Phillip Island of the Isle of Man. Now the wings reduce wheelies, which means we don’t have to cut the power, which means a faster lap time…in theory.

Secondly, at high speeds, the wings create downforce that increases stability. Generally speaking, at high speeds, the wind pressure on the rider and the bike pulls the forks up and sits the rear (see part one). Now with wings, we can reduce this effect as we have more downward pressure on the bike. The more speed increases the more downforce increases, thus creating more stability.

Thirdly, it helps fast corner entry. Not as significant as points one and two, but still worth highlighting because on extreme tracks like Mugello, or again Phillip Islands, braking can start at 170mph and above, even on a road bike. A wing controls the bike during this high-speed heaving braking, keeping the body of the bike stable and reducing the rear wheel lift to some degree. On the road, this doesn’t really matter as you shouldn’t be breaking from 100mph plus, but on a track day, even in the slow or medium group, you will be braking from 100mph plus. But again, remember when speed drops below 60mph, the wings aren’t getting enough airflow, therefore they are not working. 

Disadvantages of wings: There are two disadvantages to wings. One is they create drag, which reduces top speed and increases fuel consumption and reduces tank range. This isn’t really a problem on a high-performance motorcycle where the only issue may be tank range – at the Isle of Man a superbike will get close to using all 24 litres of fuel over just two laps. Also, on smaller bikes, like a Moto3, wings would be advantageous, but how much would they affect top speed? It would have to be a compromise. Secondly, due to the small size of the wings, they don’t work at low speed, below 60mph. Realistically it would be pointless to add them to a road-going bike capable of less than 100mph. They may look cool on a 125, but in reality, the wings wouldn’t work; they would be just for show.

The future of wings: At the moment wings are static, they don’t move depending on the speed, but in an ideal scenario they would. We could have larger wings with a large surface area at low speed, which could reduce in size slightly as speed increases or increase as like on some sports cars which ‘grow’ wings at speed. It all depends on the bike.

At the moment wings are only mounted at the front of the bike, but could a semi-active wing on the rear have an advantage, especially in racing? Could a semi-active wing, which ‘appears’ during heavy breaking help prevent the rear wheel from lifting. We know the speed of the bike, therefore the wings can react at different speeds, or reduce in size during lean, as most bikes have a system of measuring lean. We also haven’t looked at how the air leaves the bike, how we can make this smoother with wings or disturb the air for the bike following, reducing the effectiveness of its wings. There are a huge amount of possibilities which, as ever, come down to cost and technology and, in many ways, safety. It will be hugely interesting to see what the future holds.