RB hit the Circuit de Barcelona-Catalunya with a raft of upgrades which were expected to move Ricciardo and team-mate Yuki Tsunoda forward.
Instead, the pair struggled, ending Free Practice 2 only 15th and 16th, almost a second off the pace.
“We struggled a little bit today,” Ricciardo confessed.
“Competitively wise we hoped to be better.
“It’s not qualifying and we’ve got a night now to work on it and figure it out, but from a competitiveness [perspective] we were missing a bit today.”
The upgrades introduced this weekend includes engine cover, sidepod inlets, floor, and rear wing.
It’s a comparatively sizeable package, one Ricciardo suggests the team has not yet fully understood or optimised.
“With these cars, the floor’s such a big part of development,” he said.
“I think there’s still some optimism around it that once we dive into it tonight we’ll probably find how it’s working and better ways to set the car up around it.
“So hoping that tomorrow we can be a bit more positive about it all but for now I feel like we’re still digging and got a bit of work to do.”
There was, however, a positive out of the day as it marked the fist time Ricciardo had driven around the traditional circuit layout.
The chicane in the final sector in Barcelona was bypassed last year, after the La Caxia corner reverted to its original layout for 2019.
After missing the 2023 event, Friday’s running was his first taste of the ‘traditional’ Circuit de Barcelona-Catalunya layout.
“It was fun, because driving is fun, and I hadn’t been around here with then new last sector – or the old last sector but now the new one again. I much prefer that,” he explained.
“It definitely brings to track to life a bit more.”
A final hour of practice remains on Saturday, beginning at 12:30 local time (20:30 AEST) ahead of qualifying at 16:00 (midnight AEST).