A Ducati MotoGP bike featuring an aluminium twin-spar frame, as used by all the factory's Japanese MotoGP rivals, made its public debut at the start of the Valencia test on Tuesday.

Lone factory rider Valentino Rossi finished the first day of 1000cc testing alongside rivals from Honda and Yamaha in sixth position, 1.671sec from pace setter Dani Pedrosa (Honda).

"This bike is nicer to ride than the 800, even if we're only just starting our work. You can say that it's improved in some respects, while in others, it's very similar to the other bike, but that's exactly what we expected," said Rossi.

"We know we're doing preparatory work for the bike that we'll use in the 2012 winter tests, which are very important. The engine seems to be pretty good already. It's fast, although I never really found myself with the others to do a direct comparison.

"On the other hand, I'm a little slower in mid-corner, and we also have to try to improve rear grip because for now, we're not able to get the power to the ground and take full advantage of it. But it's not bad for a first taste."

Billed as an 'experimental' version of next year's GP12, Rossi believes the use of the conventional frame - relative to the carbon fibre and stressed engine of recent seasons - will allow a greater range of adjustments during testing.

"The really important thing is that we can work more freely, changing the bike's balance, the weight distribution, the measurements, and whatever we need as we prepare for the important next three months of work," he said.

Team-mate Nicky Hayden will miss the test, which concludes on Wednesday evening, after wrist fractures were discovered following Sunday's turn one pile-up.