Yamaha's carbon swingarm was used by three of their four riders at the final Grand Prix of the season, at Portimao, with Rossi and Quartararo going back, re-evaluating the option after rejecting it in previous tests.
One of the challenges on the hilly Portimao track was keeping the front wheel on the ground and that requires a lot of technique. The drivers were very mobile on their machines to prevent them from going into a wheelie.
Yamaha continued to use the carbon swingarm. Once again, Valentino Rossi used it throughout the weekend. This was the second race in a row where he adopted it. It seems that Yamaha had already looked towards 2021 looking for solutions to its M1's problems.
Carbon is an incredibly practical material for these kinds of parts. Indeed, carbon parts are manufactured by superimposing thin layers of carbon fiber. It is this layering process that makes it a practical material for these kinds of parts because it means that one can tailor the strength of the part simply by adding more layers in an area, or even by using a type of weave different carbon!
However, unlike Valentino Rossi, Fabio Quartararo mainly used the aluminum one during testing sessions, but ultimately chose to race with the carbon one. He had struggled to find an ideal setup for the race, so the decision to use the carbon swingarm may have come from the team, looking for a technical solution.
