Seems Pramac riders will be on factory Yamahas next year if Alex rins is to be believed. Good move for Yamaha not sure you can say the same for the Pramac team.
In the era of computer simulation, AI, detailed telemetry, I doubt riders have more than 1%(if) contribution towards bike development..... They can provide feedback (which might be or might not be accurate, probably this makes the difference between a good bike developer rider and not so good one) ) and that is is where it ends their contribution. I can imagine Pecco asking for the side wings to be reduced by 1.2mm and 2% more swingarm flex between 58-62 degrees lean angle.
