It’s been dropped
Even the smallest crack can be a problem. Micro fractures diminish the shells ability to fully absorb and disperse the energy from the impact. So this means that a helmet with even the smallest crack won’t perform to its full ability when you need it the most.
You’ve been involved in a collision, even a minor one
Motorcycle helmets are designed for one impact only. Even if you’ve only taken a small tumble it’s more than likely that the EPS liner has done its job and compressed to absorb the energy from the impact. So if you were unfortunately involved in another accident your helmet wouldn’t protect you as well as it should, which could lead to serious injury.
It’s had its (sunny) day
The more you ride, the shorter your helmets life span is. If you have been careful enough not to damage your helmet and it’s not suffered any wear and tear, you should consider how many miles you’ve done. UV rays over time deteriorate the qualities that make the shell effective at dispersing impact forces. So if you do thousands of miles in your motorcycle helmet, your helmets life span will be shorter than a rider who only does a few hundred miles a year.
The padding has compacted
The comfort padding in your helmet compacts over time. That creates the conditions for second impact brain injury. Your helmet needs to fit tightly so that if you are involved in an accident it can protect you. Over time the interior of your helmet can deteriorate and compact, compromising the safety. So if your helmet fits a lot looser than when you first purchased it, it may be time to replace it.
The straps or locks have failed prematurely
Even if the helmet shell is perfectly intact, if the neck strap lock has corroded under the weather and grit then it is time to change the lid. The chin strap is vital in keeping the helmet on your head in times of need.
So if you think any of these reasons apply to you, it may be time to replace your motorcycle helmet.