Riddick was a sixth-round pick by the Lions during the 2013 NFL Draft and he registered one touchdown from nine carries last season.
The rusher is now tipped to play a bigger role for the team during the upcoming campaign, with Bell confident that the 23-year-old will shine once he is given his chance.
Bell told the Detroit Free Press: "Theo's in great shape. He probably has 7% body fat. You see his routerunning from out the backfield, it's really crisp. He looks like a Reggie Bush with some of the moves you see him do in practice against some of the linebackers.
"When we sit back in the locker room, we sit back and laugh as he gets them every time with the same move, like you can't stop it.
"The only thing I can say is that he's going to keep learning and keep getting better. He keeps doing what he's been doing, he'll be a Pro Bowler in no time. I'm thinking down the line, but he definitely has the potential to be a great running back in this league."
Currently, Riddick is behind both Bush and Bell in the Lions' backfield - a duo which became the first running back tandem in league history to both top 500 rushing yards and 500 receiving yards in a single season last year.