New swingarm confusion for Valentino Rossi

Valentino Rossi admitted he is struggling to explain why a new aluminium swingarm he tested with positive results in Mugello recently created major chatter issues during yesterday’s Catalunya test.

Rossi felt the new swingarm improved corner entry grip in Mugello but he ditched it after the first day of practice at Catalunya because it created a chatter issue.

Rossi tried again to evaluate the swingarm during a one-day test at the Catalunya track yesterday, but once again a severe vibration issue on corner entry struck his GP12.

Rossi finished 11th quickest at the test and he told MCN: “We tried the aluminium swingarm but I have a lot of chatter on the front, so it is worse than the carbon and we have to try again in Aragon. In acceleration it helps us with grip but with the chatter it is impossible to use. It is when I am maximum lean angle and release the brake, there is a lot of chatter so I have to go slower.”

Asked by MCN why the swingarm worked so well at Mugello but completely the opposite at Catalunya, he added: “This is a good question because in Mugello we had one setting not so bad and we put the swingarm in and I was a bit faster but then we made some adjustments and it was so positive and I improved in two or three areas without any problem. But here no, so it depends track by track. Maybe the material is ok but we have to do some small modification to the swingarm.”

Rossi said the test ‘was not very positive’ but he will try the aluminium swingarm again tomorrow at the Motorland Aragon.

He added: “We tried to work a lot on the setting but at the end the best setting was from the race. We changed the weight distribution but I made my fastest lap time with the setting of the race, so we don’t find anything really positive. We tried to make a new comparison between the new and the old front tyre. In the race I used the new one and in the test I tried the old and it is a small difference but the new one is better, so the decision was the right one from the race.  Aragon will be an important test for us because last year my performance was very bad, so it will important to understand if we can go faster.”

For more on the Catalunya MotoGP, see tomorrow’s Motor Cycle News.