One of the most iconic sights in MotoGP™ is a rider leaning over at an almost-impossible angle whilst cornering at high speed, their knee dragging on the floor. When MotoGP Legend Kenny Roberts Sr began experimenting with the move in the early 1970s inspired by Jarno Saarinen, they started a revolution, which eventually led to all current-day riders wearing MotoGP knee sliders.
Until that point, riders were much more upright when cornering, but knee dragging saw a shift in how riders use their weight to their advantage to better control their bikes and make gains in terms of lean angle and grip.
As the technique of knee dragging has evolved over the years, technology has had to evolve too, with better aerodynamics, electronics, tyres on bikes and safety equipment to protect the riders. The most significant items in terms of knee-down rider safety are knee sliders.
In this article, we’ll examine MotoGP™ knee sliders, how they help riders drag their knees safely and bust some common myths about this technique.
What Are MotoGP™ Knee Sliders?
Knee sliders are protective pads attached to the outer parts of the knees on a MotoGP™ rider’s leathers. They’re designed to protect the rider’s legs and race suit when they come into contact with the ground while dragging knees, also assisting in the ability to gauge lean angle.
They are normally made from durable high-density plastic or polyurethane with carbon fibres and are designed to be easily removed and replaced when needed.
How Riders Use Knee Sliders on Track
Because knee dragging in racing has become such a crucial part of the MotoGP™ cornering technique, the role of knee sliders is particularly important too. Knee dragging acts as a kind of sensor for the rider so they can gauge what angle of lean they are at, allowing them to judge whether they need to adjust for safety or speed.
Using their body weight to affect the bike’s centre of gravity helps the rider to manage braking, changes in direction, maximising corner speed through the apex and subsequent acceleration out of the corner.
This is why MotoGP™ knee sliders need to be able to glide seamlessly over the surface of the track, protecting the rider’s safety without compromising the benefits of dragging knees. They also have to be strong and durable because they must add leverage and stability, sometimes even helping riders recover from momentary losses of grip, preventing crashes.
Knee Sliders: Materials and Durability
A lot is asked of the simple knee slider in MotoGP™. They need to be smooth, strong, dependable and easily removable - and this is achieved by using the right materials. Kenny Roberts might have relied on tape to reinforce his leathers in the early days, but technology has moved on significantly since then.
Plastic and polyurethane are ideal materials for MotoGP™ knee sliders because they are tough, smooth and inexpensive enough to meet riders’ needs. Nylon composites can also be used, offering even less friction, improving the sliders' glide across the track surface.
Common Myths About MotoGP Knee Dragging:
Dragging knees is just for show
There’s no doubt that seeing a MotoGP™ rider dragging their knee on the track as they hurtle around a corner at breath-taking speed looks incredibly cool. But it is absolutely not just done for the visual effect. Knee dragging has many practical advantages for riders on corners, helping with stability, safety and gaining critical feedback on lean angles.
Every rider uses knee dragging on every corner
Knee dragging has certainly become a common technique in MotoGP™ but it’s not universally used and definitely not needed on every corner. Whether knee dragging is useful depends on the type of corner - it is not used when navigating chicanes or on tight, low-speed corners, where a rider usually does not need to lean as far over.
Even on corners where they would normally drag a knee, most riders will stay more upright in rainy conditions for safety purposes. Knee dragging isn’t the only way riders use their legs for an advantage, with Valentino Rossi pioneering ‘leg dangling’ in the early 2000s as a braking technique when heading into corners.
Riders drag their knees to go faster
When you see a MotoGP™ rider hurtling around a corner with their knee dragging, it’s easy to assume that they are doing it to maximise their speed. But it’s not done to try and speed up on corners, it’s all about balance and stability as part of the cornering technique.
This can lead to carrying speed through the apex of a corner better, or faster cornering without losing too much grip, but the ultimate aim of the technique is not just pure speed.
Knee sliders: the expert eye
Former rider and Grand Prix winner Simon Crafar gives us his view on the qualities and usage of knee sliders in MotoGP™. He explains, “With knee sliders, I'd say the first thing to think about is the compounds they are made of. If the knee sliders are too hard it means they make a lot of noise when they touch the ground. It's almost off-putting, but also there's no friction. Then if they are too soft they wear down too quickly and they grip the road and pull your knee around. So they've been developed over a long time to be the right balance of hardness.”
Crafar adds, “Then I would say with the position if you're slower or riding in the rain, it's a little bit more to the front because you're going to poke your knee out a long time, a long way. Then as you get going faster and you lean over more, it's more like you try to get your knee out of the way, close to the bike, and the sliders wrap more around the side. So the leather suit has a big range for the knee slider, where you can move it around on.”
“The next thing I'd comment on is how much the riders use them,” he continues. “It varies a lot. I mean in my day there were a lot of riders that used them to the extreme and put on new ones every session. Someone I was told who used them a lot more recently would be Jorge Lorenzo on the Ducati (2017-2018). I mean a guess would be that he didn't trust the front end (of the bike) as much.”
“I think it’s about the rider’s trust in the front end and their style, which makes them use the sliders a different amount. Some force them into the road on every corner, whereas for others, like I did, or apparently Fabio Quartararo does now, the slider just kisses the surface, just feels the road. It's more like a gauge, but it's there if the front goes (front tyre loses grip), they can try and hold the front up (prevent a crash). So they vary from having new sliders every session all the way through to guys getting several days of use out of them.”
An important piece of MotoGP™ rider safety equipment
So overall, knee sliders perform an important role in MotoGP™, preventing abrasion of the riders’ leathers on the track, protecting the knee from damage and friction against the asphalt and assisting the riders with their balance as they gauge the optimum lean angle on cornering.
Looking for more great MotoGP™ content? Follow the official MotoGP Facebook page, for exclusive videos such as this clip of Marc Marquez forgetting to put his knee sliders on at the 2024 Dutch GP at Assen.