In an image forming apparatus having a subunit movable between closed and open positions, the nip between media alignment rollers is opened automatically when the subunit is opened. A drive roller and a backup roller are disposed in a housing, wherein the bearing holding the backup roller is segmented. A rear segment is disposed on a flexible arm, and is biased towards the front segment, biasing the backup roller to contact the drive roller to form a nip for bump alignment of media sheets. A bell crank engages a rotary member or rotary member frame mounted on the subunit when the subunit is closed. When the subunit is opened, the bell crank disengages the member, pivoting a link member having a cam surface and engaging the cam surface against a cam follower surface on the housing, forcing the backup roller to a position spaced apart from the drive roller.