Suzuki team-mates Maverick Vinales and Aleix Espargaro took opposing decisions on their future chassis choice, at Monday's Catalunya MotoGP test.

Vinales, who finished fourth in the race, declared an evolution design to be a clear step forward and plans to race with it next time at Assen.

But Espargaro, who unlike Vinales used the new chassis during the race weekend, felt 'extremely better' after switching back to the standard chassis, leaving him 'really happy and at the same time really angry'.

Both riders had used the evolution frame during a private test at Valencia, prior to Catalunya.

"For the race weekend we decided to go back to the standard frame as it was too risky to go with the new one, but with the work we've done today, and the new settings we tried, the improvement is significant," Vinales declared. "The feeling between this evolution and the standard chassis was exactly the same feeling at Valencia as here, that I can close better the corners, keep a tight line.

"For example, with a little bit of gas, the bike turns a little bit more, so I don't need to slide so much. So you save the tyres and for me it was better to close the corner, which was important. You don't need to use so much the gas to close the corners."

Vinales set the pace during the first half of the test courtesy of a flying 1m 44.310s lap on new Michelin tyres - good enough for third overall at the end of testing - but it was his pace on the harder tyre that convinced him the new chassis is better.

"It was 12 noon, and already 49? on the track, I put hard and hard [tyre compounds] and I did 1m 44.5s, with the new chassis. So I think we made an improvement from yesterday," said Vinales, who will work with Ramon Forcada at Yamaha next season.

"Anyway, still we need to work more, because the others are also working. If we find a little bit, and the others find a little bit also, then we are still behind. So we need to keep working."

And you will use the evolution frame from Assen? "Yes, I think so. We are going to try."

But on the other side of the garage, Espargaro declared using the new chassis to have been a 'big mistake' during the race weekend.

"I was confused and decided to use the [new] frame we tried in Valencia two weeks ago. And was a big mistake, like I did at the beginning of the season" Espargaro stated, referring to his ill-fated use of a previous 2016 chassis before joining Vinales on the standard [2015] version from race day in Qatar.

"I was in too much of a hurry to decide to race with the chassis we tried in Valencia.

"This morning again I didn't feel good [on the new chassis]. I crashed, and in the afternoon I decided to come back to our standard chassis and immediately with the hard rear tyre I was almost one-second quicker than in the race.

"I felt extremely better. I was really happy and at the same really, really angry.

"It confirmed that from now on we will not try more chassis and focus on our current bike. So for sure we will keep working on the standard chassis in Assen because it's good."

Espargaro - on pole for his home event one year ago - failed to reach Qualifying 2 on Saturday, before retiring from eleventh in the race with a technical problem.

The Spaniard, yet to confirm his 2017 team amid rumours of a switch to Aprilia, was fifth fastest at the test but explained that the lap times on the soft tyre didn't mean much in terms of race performance.

"We tried three different rear tyres. One was much better to do the lap time, like a qualifying tyre, but I don't understand the meaning because what we need is a harder tyre with better feeling for the race distance. The soft tyre was better, but there was no chance to race with it, even if the race was only 10 laps."

By Peter McLaren