(1) When overtaking and passing another vehicle or pedestrian within the lane or when about to enter the lane if the overtaking and passing cannot be done safely within the lane.

(2) When preparing for a left turn, the operator shall stop and dismount as close as practicable to the right-hand curb or right edge of the roadway and complete the turn by crossing the roadway on foot, subject to the restrictions placed on pedestrians in Chapter 5 (commencing with Section 21950).

(3) When reasonably necessary to leave the bicycle lane to avoid debris or other hazardous conditions.

(4) When approaching a place where a right turn is authorized.

(b) No person operating a motorized scooter shall leave a bicycle lane until the movement can be made with reasonable safety and then only after giving an appropriate signal in the manner provided in Chapter 6 (commencing with Section 22100) in the event that any vehicle may be affected by the movement.