Tony Capaldi's position will be challenged by the arrival of Manuel Commingues from Swindon but it's the other three that City must try to keep.
"I do not want to lose any players. We are looking to build on what we have now," Ridsdale told the Echo.
"I have met with Roger's agent and Kevin's too and I will be meeting with Glenn's agent this week.
"We believe we have some lucrative packages to offer them and are very optimistic they will commit their futures to Cardiff City.
"We firmly believe Roger and Glenn Loovens are probably the best central defensive partnership in the Championship.
"Therefore, our objective this summer is to keep those two players together to ensure our best push at the league next season.
"The only way we would consider selling Roger, or Glenn for that matter, is that if we received a knockout bid and the manager thinks we could replace them."
With the imminent sale of Aaron Ramsey to Arsenal City must look to strengthen now and now lose anymore quality players. It appears that some money will be available to Dave Jones to put together a side that can chalenge for promotion next season.
"We are working flat out to try to bring in the players Dave has targeted," Ridsdale continued.
"Money will be made available for him to bring in the players he wants if that is possible.
"The one thing I can assure everyone is that we will go into next season stronger than we left the last."