'Sons of Anarchy' shifts into high gear for Season 5 [Exclusive Video]

The badass bikers of "Sons of Anarchy" come roaring back to the tube in September -- and Yahoo TV! has an exclusive look at a teaser for Season 5 of the FX series.

The clip shows the motorcycle club from Charming, California, traveling the open road while the song "Trouble Weighs a Ton" by Dan Auerbach of the Black Keys plays. As the bikers round a bend, they approach a small bridge where "club women" Tara (Maggie Siff) and Gemma (Katey Sagal) are. Gemma runs out in front of the moving pack of bikes, raising her hands as if she were telling them to stop. The first motorcycle in the pack -- with Jax on it -- skids, crashes through the railing, and goes over the side. Tara has a look of horror on her face and Gemma screams as bike parts fly through the air.

[Related: 'Sons of Anarchy' scoop: Ashley Tisdale cast as a 'desirable escort']

The relationship between the two women is a major focus this season now that Jax is president. Tara stands by his side, leaving little room for Gemma. "Gemma loves Tara but might just be a little threatened by her now that she's suddenly been displaced as queen of the club," Sagal recently told TV Guide. "Gemma, who'll be getting her drink on, doesn't like to take s--- from anybody!" As for Tara, Siff told the magazine, "She will be getting a little more messed up in the head and volatile. You will also see her smoking pot to take the edge off."