Why do motorcycle helmets expire? That is a common question among many motorcycle newbies, and it is reasonably understandable. When you look at a helmet, it does not appear to resemble anything that we connect with as being biodegradable. However, it is. A helmet will change and lose effectiveness over the course of its life, and there are several reasons for that to occur.
A helmet lifespan is dependent on a variety of factors. How often do you use your helmet? Where is it stored? What materials is it made from? Has it experienced any significant or minor impacts? All of the answers to these questions and more will help to determine the lifespan of a helmet, and even though many manufacturers claim a lifespan of seven years, that is also dependent on the responses to the above questions. However, when discussing the longevity and durability of your helmet, the lifespan depends mainly on its construction.
The production of helmets has evolved over the decades, going from metal to Kevlar and fiberglass and polycarbonate. Each iteration has been made and adapted to increase the protective quality and ensure that riders taking a spill don’t end up with significant brain-damage. While materials have changed over the years, the current standard is a combination of two segments: (1) the comfort liner or inner body and (2) the outer or hard shell.
The comfort liner is likely the reason for the motorcycle helmet expiration because it is made from EPS foam, which can lose its shape over time. However, foam also provides a soft and comfortable cushion for long-term use. Additionally, the foam interior provides a rider with a shock absorbent pad necessary for softening the blow from a collision.
The outer shell of a helmet is the most durable and resilient surface. It is typically made from a polycarbonate or a combination of fiberglass and Kevlar. However, you can also have pure fiberglass helmets as well. The shell is designed to be lightweight and to prevent the risk of penetration as a result of an abrasive collision. Therefore, the outer shell protects your head from obstacles and the inner liner protects it from impacts.
As stated above, the comfort or inner liner of your helmet is likely the reason for helmet expiration. Expanded polystyrene or EPS foam is used for comfort liners because it is a durable and customizable substance. However, it is not an inflexible material, and it can lose shape and even volume over time. Therefore, it does need replacing. However, while it is not a perfect substance, it does provide advantages over other materials.
A problem with many protective options is their rigidity. For example, a metal helmet without an inner foam cushion is likely too inflexible, leaving a rider to bear the full force of an accident. A helmet is designed similar to a bumper in that it is meant to absorb part of an impact. Being too rigid only creates another solid surface to collide with. However, some rigidity is necessary to prevent full contact. Foam is the perfect balance of rigid and soft because it is flexible while still maintaining form.
Cushion, Absorption and Deceleration
The design and construction of foam mean that it is capable of compressing and absorbing impacts. This functionality of foam makes it unique in its ability to slow down and cushion collision. While the outer shell creates a brunt and impervious surface the EPS interior provides room for deceleration, making the accident less abrasive.
However, while foam is a superior substance for reducing the adverse effects of potential head trauma, the degradation of the material reduces the lifespan of a helmet. Unfortunately, the question of, “how long are motorcycle helmets good for?” is not an easy one to respond to because the answer depends on a few variables: storage, integrity and use.
Recommended Versus Actual Replacement
How often should you replace a motorcycle helmet? Well, that depends. Manufacturers typically rate their helmets for seven years. However, that is based on certain usage and optimal storage and use conditions. While seven years is the general rule, many riders will argue that a helmet should be replaced every three to five years depending on your riding style and region. Therefore, lifespan is not set in stone. You can replace a helmet in as little as three years, or you can choose to take the manufacturers word for it, but in either case, you should consider a few things.
While it may not seem like region and storage conditions should affect your helmet, they do. Granted, the outer shell should hold up just fine in all types of conditions, but the inner foam lining is biodegradable, meaning that certain conditions can speed up the process of degradation. Therefore, to get the most life out of your helmet, store it in a cool, dry place to reduce the effects of warm and humid conditions.
Integrity refers to the overall condition of the helmet. If you have already experienced a few spills on your bike, and your helmet is cracked or damaged, then it is time to replace it. Any cracking, scratches or dents should be cause for concern, and likely should result in the replacement of the helmet, whether it is only one day or 5 years old.
Lastly, use refers to how often the helmet is worn. While many helmets are designed for daily use, some are not. Also, while some helmets are designed for sports, like motocross, others are not. Always buy a helmet that suits your needs and intended use.
While helmet expiration may sound strange to inexperienced riders, most experienced motorcyclists know and understand the importance of replacing a helmet before its time. The construction of helmets, while suited for impact and lessening the effects of head trauma, make them impermanent. While the outer shell is durable and resilient, the EPS lining is biodegradable and will not last forever. Therefore, when the time comes, do your research and find the best motorcycle helmets for your needs.