Final answer:
The greatest danger for a rider when passing parked cars is the risk of a door being opened suddenly. Riders should maintain a safe distance from parked cars and be alert to the possibility of a door opening. Another danger is the risk of unexpected movements by parked drivers.
Step-by-step explanation:
When passing parked cars, the greatest danger for a rider is the risk of a door being opened suddenly. This is known as a "dooring" incident, where a driver or passenger opens their car door without looking and the cyclist collides with it.
To avoid this danger, it is important for riders to maintain a safe distance from parked cars, ideally at least 3 feet, to provide a buffer zone. Additionally, riders should be alert and anticipate the possibility of a door opening at any moment, especially in urban areas where there is more car traffic.
Another potential danger when passing parked cars is the risk of unexpected movements by parked drivers. They might suddenly pull out from the parking spot without checking for approaching cyclists, leading to a collision. Riders should always be aware of their surroundings and be ready to react if a parked car starts to move.