Can Ducati solve its chatter mystery?

MotoGP

Ducati has a serious chatter problem and MotoGP championship leader Jorge Martin can’t understand why other manufacturers aren’t struggling with the same phenomenon. Plus, what does chatter do and what causes it?

The high-frequency vibration of chatter can be so strong it rattles your teeth and blurs your vision, but most importantly it has your tyres bouncing off the asphalt

The high-frequency vibration of chatter can be so strong it rattles your teeth and blurs your vision, but most importantly it has your tyres bouncing off the asphalt

Dorna/MotoGP

Author

Mat Oxley

Ducati has dominated the last few years of MotoGP with its all-powerful Desmosedici, but the bike now has a weak point that is proving problematic to fix.

Here are a few words from Ducati’s fastest riders from the first two rounds of 2024.

Pramac rider Jorge Martin talking about his Qatar Grand Prix weekend: “We had vibration entering corners, also in the middle of corners and when I open the throttle. The worst was entering, because you can’t do anything — you just have to pick up the bike and wait for it to disappear”.

Martin after the sprint in Portugal: “I’ve struggled all weekend with the soft — lots of rear vibration. We are pushing too much into the rear tyre and every lap was worse. We’ve had lots of problems with chatter here and in Qatar — we need to solve it, or we’ll have the problem all season. The other brands don’t have it — I don’t understand why.”

Factory rider Pecco Bagnaia after the Qatar sprint: “I had big chatter from the rear — vibration after three or four laps”.

Bagnaia after the main race in Portugal: “Today I had chattering — we didn’t expect it”.

And factory Honda rider Luca Marini, whose RC213V doesn’t have chatter because it doesn’t generate enough grip, talking in Qatar: “The Ducatis have chatter because they have lots of grip”.

You get the idea — Ducati’s fastest riders are struggling with chatter, which forces riders to slow down or risk crashing, because the tyres are literally bouncing off the racetrack.

Sure, Bagnaia and Martin won the first two grands prix of 2024, but chatter is like a strange technical disease — once it’s infected your motorcycle it can rear up when least expected, according to track conditions, tyres, settings and so on.

And even when you think you’ve fixed it, it can return when you move onto the next track or the next set of tyres. Like Bagnaia at Portimao – he had chatter with the grippier soft rear in the sprint and didn’t expect it with the medium rear in the GP, but it came to haunt him anyway.

MotoGP 2

Bagnaia leads Pedro Acosta and Marc Márquez in the Portuguese GP – he didn’t expect to have chatter in this race but he had it anyway

Mostly, as Marini said, you get chatter when you’ve got lots of grip, which has been the Ducati’s strong point in recent years. And it’s therefore worse on softer, grippier tyres, which is why it’s worse in sprints and in qualifying.

And that’s why chatter was a bigger issue at super-grippy Losail than at Portimao.

Chatter isn’t only worrying GP24 riders in the factory and Pramac teams, it’s also causing problems for GP23 riders like Marc Márquez, who was on course for pole position in Qatar until the rear of his bike chattered like crazy in the penultimate corner.

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So what’s going on? Michelin has all-new front and rear slick compounds this year, using a new chemical mix for harder rubber that grips as well as softer rubber, for greater durability and reduced swelling under high pressure.

During the first two MotoGP weekends of 2024 a few riders from some other manufacturers briefly mentioned chatter, but the fastest Ducati riders talked about the problem all the time, so it seems like the Desmosedici is least suited to some of these new compounds.

The irony, of course, is that Ducati has had a tuned mass damper in the Desmosedici’s seat hump since 2017, designed specifically to damp out chatter and vibration. The fact that the mass damper hasn’t fixed this particular bout suggests it’s a difficult one to cure.

Chatter has been a problem in bike racing for many decades, but there’s been little talk of it in MotoGP in recent years.

The last time it was a big deal was in 2012, when Casey Stoner and Jorge Lorenzo were fighting for the first 1000cc MotoGP title. Halfway through the season Bridgestone switched to a new front slick, which Lorenzo’s Yamaha loved, but Stoner’s Honda hated, because it caused the RC213V’s front end to chatter like hell.

Martin with crew chief Daniele Romagnoli

Martin with crew chief Daniele Romagnoli (thumbs up). Martin is worried that chatter could afflict Ducati throughout the season

Red Bull

“The new tyre has destroyed us!” said HRC boss Shuhei Nakamoto at the time. Indeed it may have cost Stoner the 2012 championship.

Chatter is caused by resonances within the motorcycle. Most parts of a motorcycle chassis are a spring, from the frame to the swingarm and from the triple clamps to the tyres. Even if a part only bends and springs back a millimetre or two, it’s still bending and springing.

When different parts of the motorcycle start resonating with each other they create a high-frequency vibration, which the suspension struggles to cure, especially at high lean angles, because the forks and shock don’t work properly when the bike is leant over.

Even engines can cause chatter. Aprilia’s narrow-angle RS-GP V4, replaced in 2020 by the current 90-degree V4, is a case in point. The engine vibrated badly, which caused chatter and made the bike super-nervous, especially on the brakes.

Chatter is like riding on a washboard

Musicians have their own version of chatter, which they call sympathetic resonance, which can be desirable or undesirable, depending on the music. When guitar makers don’t want it, they incorporate features to dampen the resonance.

Chief Öhlins MotoGP engineer Mats Larsson has been dealing with chatter since the 1990s, so he’s seen how it comes and goes.

“Chatter is like riding on a washboard – the tyres can jump up and down between half a millimetre and six millimetres,” he says.

(You probably don’t need me to tell you that tyres don’t grip very well when they’re half a millimetre or more above the road.)

“The tyres themselves have a certain amount of damping in them,” adds Larsson. “A front tyre’s natural frequency is around 17Hz to 19Hz [17-19 cycles per second], so if you have some kind of irregularity or imbalance in the motorcycle that matches that same frequency then the vibration starts. It may only happen at a certain speed in a certain corner at a certain lean angle.”

Enea Bastianini’s GP24

Enea Bastianini’s GP24 with tuned mass damper in seat hump. Bastianini seems to have less chatter than other Ducati riders – it’s a very particular phenomenon

Oxley

In other words, chatter is a very specific phenomenon. For example, when Honda had front chatter in 2012 it was worse in right-handers than in lefts, because the mass of the RC213V was fractionally different on its right and left sides.

“We have teams coming to us, saying, ‘Please make a special damping setting to damp out the chatter’ – sometimes that works, so the vibration disappears,” Larsson continues. “Then they change something in the settings and it comes back, maybe in a specific point of the track, so they raise the bike, so the rider needs to lean less at that point, or they lower the bike, so the rider needs to lean more, to avoid the chatter.

“Nowadays it can be so many things – chassis, engine design, special clutches, electronics or gadgets.”

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Whatever the specifics, it seems like the combined forces and frequencies of the Ducati and the new Michelins are creating a perfect storm for Martin, Bagnaia, Márquez and other Desmosedici riders.

Ducati engineers must be working like mad to fix this issue, because chatter can be difficult to fix in the long term. They will have been looking at all the different resonances coming from the engine, clutch, devices and so on. There may even be revised frames or swingarms – for different flex – at COTA, or perhaps for the Jerez tests, after the Spanish GP.

(By the way, Ducati’s flexi front engine hangers, revealed in this blog two weeks ago, aren’t new, they also feature on recent iterations of the Desmosedici.)

Of course, there is someone else who can help: the rider.

When engineers can’t fix problems it’s the rider’s job to ride around them. Riders can exorcise chatter issues by using different riding styles – adjusting lean angle, using the throttle and brakes in different ways and so on. At one time Valentino Rossi used to apply the front brake mid-corner to change the forces and frequencies to banish front-end chatter.

Ducati’s chatter may be a thing of the past at this weekend’s Americas GP at COTA, but it may not be gone forever.

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