All methods of transportation have risks, but bicyclists face unique dangers. A report by Denver Public Works shows that each year between 2008 and 2012 averaged 265 bicycle crashes. That only counts the number of accidents that were ultimately reported.
Bicyclists are already vulnerable, so they should not put themselves in any greater danger by choosing to wear headphones while riding. While it is not necessarily illegal to wear headphones while riding a bike in Colorado, there are other reasons why this action is ill-advised.
You need to be able to hear everything around you
Your sense of hearing is important whether you are on roadways or open mountain trails. You need to be aware of what is going on around you and if you need to react to an oncoming ambulance. Your hearing also allows you to listen to any problems your bike might have. For example, if you hear a clunking noise, then you need to stop biking, find the source immediately and fix the issue before something dangerous happens.
You need to acknowledge others' presence
Most bicycles come with a bell to inform other riders that they are coming up behind them. When one bicyclist wears headphones, he or she is unable to acknowledge this presence, and it comes across as disrespectful. Everyone needs to share the road together, so do your part and be mindful of others. It may be a long trip to your destination, but you need to remain cognizant at all times.
It decreases overall performance
When you are trying to find a certain building, listening to music takes away from your focus. Your brain is trying to do multiple things at once with listening to music and keeping an eye out for something specific. This is also detrimental when you are mountain biking in the woods because you need to remain aware of trees and other potential obstacles in your path.