Dax Shepard: 'Wife Kristen Bell muscled her way into CHiPs movie'

Dax Shepard wasn't convinced his wife Kristen Bell would be a good fit to play his onscreen ex in CHiPs, because her character is such a "jerk".

The former Parenthood star wrote and directed the film adaptation of the 1970s traffic cop drama, in which he also features, but he had no plans to cast Kristen in the project, because he didn't think there was anything suitable for her.

However, the Frozen actress, who is known for her kindness, made Dax change his mind after insisting she would be great for the role of Karen.

"I didn't want her to play the role because my wife in the movie is a terrible human being, and my wife (in real life) is such a wonderful (person)," he explained on U.S. breakfast show Good Morning America. "So she plays a real jerk and I didn't think of her, naturally, but she read it and thought it was funny and she wanted to do it."

And Dax confesses he didn't have much choice, because Kristen would have found a way into the comedy one way or another.

"She's the boss so she did it," he smiled. "She could have played (second male lead) Ponch, really, if she (wanted to)!"

Ant-Man's Michael Pena tackles the part of Frank 'Ponch' Poncherello, the role made famous by Erik Estrada in the TV original, while Dax portrays his rookie partner Jon Baker, previously played onscreen by Larry Wilcox.

In addition to letting Dax live out his childhood CHiPs dreams, the movie allowed the actor-turned-filmmaker to indulge in his love of motorcycle riding, as the traffic cops cruise around onscreen on Ducati bikes.

"I'm a big, big motorcyclist, it's my number one hobby, so this movie was purely an excuse," he joked. "I was born atop a motorcycle! This whole movie was an excuse for me to ride that thing around... 'Honey, it's paying the bills, putting the bacon on the table!'"