1: Rider can see behind themselves
Having more information about your immediate environment is always helpful.
Obviously, you have to see where you are going but what happens when things come at you from different directions.
Cyclists often have great peripheral vision because they’re usually scanning for obstacles that may take them off the bike.
However, we can only see roughly 180 degrees from left to right. Without being able to see behind us, we rely on other senses such as our hearing to warn us of rearward approaching objects (automobiles, motorcycles, etc).
Sometimes, it is not tremendously reliable as other factors such as noise or headwinds may diminish our ability to hear approaching objects.
The solution: a device such as one used on other moving vehicles to give us easy access to this information.
2: It is safer (maybe?)
It is a common idea that traveling in groups give cyclists more visibility.
However, it is not always convenient or practical for riders to always travel in groups.
This necessitates a rider to be able to take care of themselves by making sure that drivers behind them are at the very least paying attention.
Initially, when you use a mirror, and you see an approaching car, you don’t know what to do with this information.
Most of the time, the driver will see you, slow down, and/or move over to pass.
You learn to ‘tune’ these people out as they’re generally not a threat.
As time goes on, you learn to anticipate the actions of the people that will not give you as much room, the people that are not paying attention, or the people that potentially want to harm you.
3: Traveling In Groups
When traveling in groups, it presents a challenge to all road users. Groups do not always stay together, and groups often spread out on a lane or ride single file.
Drivers often have to gauge when it is safe to pass (or they don’t and pass anyway).
Giving a ‘heads up’ to fellow riders that there is a vehicle in the immediate area is a common practice in groups (‘car back!’ or ‘car passing!’).
The idea, of course, is to let fellow riders know that it’s probably not a good idea to engage in a risky maneuver that may place anyone in danger.
4: Small Groups
When in small groups, it’s a benefit to see where everybody else is. It would be an assumption that small groups intend to stay together for the benefit of drafting or just pacing each other.
There have been many times where I may have dug deep on a section of road only to look over my shoulder and see nobody there (oops!).
On the other hand, maybe I wasn’t feeling my best, and my training partner put their head down and took off only to see them look behind themselves minutes later to see me wave at them from half a mile behind.
Regardless of the situation, if you are up ahead, you can still keep an eye out for your partners even if they fall a bit behind.
5: Large Groups
Larger groups add an element of competitiveness.
Whether on a ‘drop ride’ or ‘no drop ride,’ riders are constantly changing positions and speeds.
Speeds tend to be a little bit higher because everyone is enjoying a draft, so with shorter reaction times, your main attention should be forward.
However, I often glance up at the mirror to see how well I am doing (is anyone struggling), or how well I am not doing (is everyone engaged in conversation).
In addition, I have immediate information regarding where I am in the peloton.
- Am I the last one?
- Are the riders behind me about to be dropped?
- There’s a batch of riders approaching.