What should a motorcycle rider be able to see in their rear-view mirror?

A motorcycle rider should be able to see about half of their lane and part of the next lane in their rear-view mirror to maintain proper awareness of their surroundings. This view allows the rider to monitor not only the vehicles directly behind them but also any potential threats in adjacent lanes. Such awareness is essential for safe riding, especially during lane changes or merging into traffic.

By having a broader view of the space around them, the rider can react appropriately to vehicles that may be approaching from behind or from the side, thus enhancing overall safety on the road. A mirror that only shows vehicles directly behind or only focuses on the lane next to them would provide limited perspective, potentially leading to hazards that the rider may not notice in time.