Valentino Rossi admits Ducati is far from the pace of the leading teams following a difficult start to his French GP weekend on Friday.
The Italian finished both practice sessions over a second behind pace-setter Casey Stoner, as the Ducati rider continued to struggle with the handling of his bike.
Rossi admitted he made some changes near the end of the second session that would have allowed him to go slightly faster had he had time, but the multiple-time world champion conceded his team was still too far from the front.
"For sure the result is not positive for us because first we needed five more minutes in practice because a change to the rear shock of the bike gave me a better feeling but I could only do two laps, so maybe with a lap or two more I could have improved my laptime and my position," said Rossi.
"Anyway, we are still too far because we struggle very much under acceleration. The bike is too nervous and moves very much because I think we made a mistake with the rear end. Also we can improve our electronics systems.
"So we have to try to fix the problem because I lose a lot of time."
He added: "The problem is that I don't have a very good feeling in the entry and I have some understeer so it means that I enter the corner like an old lady with the supermarket bags on the back. I'm very slow in that area and we don't expect a big step from the new chassis.
"I think with two or three laps I could have improved two or three positions but anyway we are far. We still don't understand the problem."
Rossi conceded the Hondas looked unbeatable at the moment, after the Japanese manufacturer dominated both sessions.
"The difference in acceleration is impressive. Also now the Honda is the bike with a good set-up. It's stable, similar to the Yamaha but with 20 horse power more. "