Cal Crutchlow claims that, despite him being a Honda-contracted rider, his bike was not as competitive as that of Marc Marquez and Dani Pedrosa in MotoGP's Jerez race.
Crutchlow started on pole but ended up crashing out at Turn 1 while running fourth, while Marquez ended romped to v ictory.
The factory Honda team introduced a new carbon swingarm at the beginning of the 2018 season, and both Marquez and Pedrosa used it at Jerez.
However, LCR's Crutchlow, who signed a contract with HRC last year and is riding a 2018-spec Honda this season, hasn't received the new part.
Crutchlow said that while he had the pace of Marquez and Pedrosa during Friday and Saturday, in the lower-grip conditions of the race he had to push to match the "cruising" Marquez, which led to his eventual crash.
"I don't think Marc would have won so easy if he had my bike today, but that is my opinion," said Crutchlow. "He would have had still a great shot at winning the race.
"I was pushing to make up ground, I have the data, I look at every video in Texas, every video here.
"On Friday, they are leaving black lines everywhere, Saturday morning sometimes they do black lines, depends on which bike they are on, and now they just cruising.
"Marc was absolutely cruising today and you can see I had the pace all weekend, but when the grips are lower we didn't have the pace because we don't have the same equipment.
"I am not allowed to say directly a part but my bike is very good."
When asked if the carbon swingarm makes a big difference, Marquez claimed it doesn't, but confirmed that it provides a bit more grip.
"Basically in this circuit we don't feel a big difference but looks like we can little bit more grip with the used tyre," he said on Saturday.
"This morning I did the best laptimes with the aluminium one so is no big difference.
"This afternoon I use the carbon one because give little bit extra grip but is very small difference."
On Saturday, Crutchlow said that he accepts he won't get to use the carbon swingarm as he is competitive enough without it.
"I have to obviously be very careful because I'm supported very very well by Honda, I'm pleased with my package, I'm pleased with the support I get.
"I'm not going to get it, it's as simple as that, and I'm not going to get it for a long long time, especially now I'm beating them.
"That's the way it works. I'm not stupid."
Additional reporting by Matteo Nugnes and Oriol Puigdemont