Bi-fold doors open roughly when the setting is broken, the hinges are damaged or the track is blocked. Regular maintenance and gentle use keeps these situations from occurring. These doors are easy to fix with a few basic tools.
Rough opening of bi-fold doors can occur from improper installation or years of heavy use. When troubleshooting them start by inspecting the floor and ceiling tracks to verify the rails are clean and free of rust or damage. A bend in a track makes for very rough opening and closing of doors.
The door itself often experiences fatigue at the joints or breaking of the track feet. Oil the hinge pins and tighten screws at the joints. Replace cracked or broken feet at the top and bottom of the door. Use expandable feet, so the bi-fold door fits snugly in the tracks and does not bounce as it slides, which can cause additional door fatigue.
When installing a bi-fold door, check that it is properly mounted to the walls, so that it hangs straight. A crooked bi-fold door causes rough opening because the feet are either pushing into the floor or ceiling as it opens. Use a level to verify these doors are plumb.