Bruce was confirmed as new Wigan Athletic manager yesterday and Birmingham's board want Black to take charge in his stead.
"It's obviously disappointing, the gaffer brought me to the club," the defender told Sky Sports News. "I don't know too much about it, I'm sure we'll find out more in training."
On Black, Ridgewell said: "He's obviously popular, all the players like him, we got on well with him when the gaffer (Bruce) was here.
"All the players trust him and I'm sure he'll be good.
"It is one of those things that happens. Managers come and go. It's hard to take - personally as well, I'm disappointed to see him (Bruce) go. Sometimes in football that happens and as a club, and players, we've got to try to get on with it."