Bale joined Madrid from Tottenham for a world-record fee of €100 million, six million more than what they paid for Ronaldo in 2009.
That said, Salgado cannot see the 24-year-old, who scored 26 times in all competitions for Spurs last season, exceeding the Portuguese's incredible goalscoring exploits.
"It is a complicated issue," Salgado said.
"Firstly supporters can't expect that because Real Madrid paid more money for him [Gareth Bale] than Cristiano Ronaldo, he will score more goals than Ronaldo. He will never do it."
The Wales international has made just three appearances for Carlo Ancelotti's men due to a thigh injury, although he did find the net on his debut in a 2-2 draw at Villarreal.
Salgado faced Bale in his time with Blackburn Rovers and, although he is a big admirer of his talents, the 37-year-old knows that it will be difficult for the Welshman to adjust to life in Spain's top flight.
"I suffered against Gareth Bale as a player," he added.
"He is an awesome player with huge potential but he is used to the Premier League and he is still on his way to getting used to the Spanish league.
"It doesn't matter how much money you pay for a player because later on players need to adapt to the style of play, the country and the culture.
"Let's see how he deals with those things. Real Madrid has a lot of pressure and if you add into it that Bale is the most expensive player in Real Madrid's history it is going to be massive for him."