Aleix Espargaro urges Honda to produce “definitely better” carbon fibre swingarm

Back-to-back tests during Friday practice at the British MotoGP have convinced HRC wild-card Aleix Espargaro that a new carbon fibre swingarm should be offered to Honda’s full-time riders as soon as possible.

While Ducati has used a carbon fibre swingarm almost exclusively since the end of 2009, Honda only publicly debuted a composite design for its MotoGP project a decade later.

It lasted a few seasons before HRC reverted to aluminium during 2022, via a partnership with Kalex, as it attempted to solve the RC213V’s persistent handling issues.

But with tough-to-cure vibration problems hampering otherwise major progress with its 2025 machine, the new carbon fibre project was fast-tracked into use for Espargaro’s second wild-card of the year.

“We compared in both sessions the carbon and aluminium swinging arm and I'm quite happy about it,” Espargaro said. “It is a small improvement and hopefully in the tracks where you have a lot of vibration it can help a little bit Joan and Luca.

“It's not easy to test an item like this on a race weekend. But I jumped between bike 1 and 2 to compare and it's definitely one step better.

“Apart from the feeling, it’s lighter, so it's good and I really can't wait… This is not the worst circuit for the vibration, so maybe in the circuit where you have a lot more vibration it can help more.

“For me they have to start to produce as soon as possible to bring to the factory boys.”

Like Ducati, KTM and Aprilia use carbon fibre swingarms. Yamaha's design is officially described as 'Aluminium/CFRP'.

Although long corners - of which Silverstone has many - typically trigger chatter for the Honda riders this season, Espargaro explained that it’s more of a problem on left turns than right.

“Our biggest problem is in the fast left corners, and there are not much left corners here, it's more right turns,” he said.

“I still have a little bit [of vibration] but for me the torsion of the swingarm on the carbon bike is a little bit more smooth. So really, I can't wait. It would be good to test it in Jerez, but anyway here it has been positive.”

Identifying cause of vibration “a nightmare”

The intermittent nature of the chatter, not just from left to right handers, but circuit to circuit, has made the root cause hard to find.

Although confident the swingarm is helping, Espargaro suspects it could be originating from the engine.

“It's difficult because we did many brainstorms with Romano [Albesiano, HRC technical director]. With Taka we talk also a lot. I talk also with Mir… We don’t understand really where this vibration can be coming from.

“This is why we accelerated the carbon swingarm test, because it’s something new that can help and this is why I'm racing with it here.

“But the biggest problem on the vibration is that we are not able to understand where it's coming from. And it's really a nightmare because we are trying many things.

“My thought is that it's coming from the engine, but this is very difficult really, if it's coming from the engine, to improve for this year. So we're trying everything.”

The good news was that, even without the carbon fibre upgrade, LCR’s Johann Zarco was eighth fastest on Friday while HRC’s Joan Mir topped the session before being pushed to twelfth.

“Johann did a very good lap but if you check the pace of Mir today, it was very solid, I think fast enough to fight for a top 6.

“Especially Joan can do one step forward in the qualifying because his pace was impressive today.”

Former Silverstone winner Espargaro was 21st on Friday, 2.027s from Alex Marquez but ahead of LCR Honda rookie Somkiat Chantra.

“Still when I try to push to the limit with the soft tyre, I make too many mistakes. I'm too stressed! He said. “I feel bad with myself because I had the feeling that I can go faster.”