To unlock the Off Balance trophy in you will need to knock 19 bikers of their bikes with the Phoenix's Dodge.
You will receive the Phoenix vehicle early in the game. To perform a dodge, you will need to press
. To know a biker off its bike, approach from the side and press
and use the left stick to point in the direction of the bike.
Once you have knocked 19 bikers off a bike, the trophy will unlock.