When should a motorcycle rider use their turn signals?

Using turn signals is essential for safe motorcycle riding, particularly when changing lanes or making turns. This practice is crucial for communicating intentions to other road users, enhancing the safety of all involved. By signaling, riders alert drivers and pedestrians to their planned actions, allowing others to anticipate and react accordingly. This is vital not only for the rider's safety but also helps in maintaining traffic flow.

In the context of the other choices, while there may be some relevance to particular situations, they do not encompass the full spectrum of when signaling is necessary. For example, only signaling when entering a highway doesn’t address safe lane changes or turns intersections where visibility and awareness are crucial. Likewise, signaling before stopping is not standard practice; it is more about indicating directional changes rather than stopping, and only using signals in heavy traffic diminishes their value in the broader context of rider safety on all types of roads. Therefore, using turn signals consistently when changing lanes or making turns is the most comprehensive and appropriate practice for motorcycle riders.