How long can I use a bicycle helmet?

Question

My helmet for road cycling has seen some good use and I was considering to replace the padding because it is falling apart, but at this point I was wondering myself: Should I even keep the helmet?

I found some old questions that state - barring crash or impact - the "rule" are ~5 years if the helmet is structurally intact:

• When or how often should I replace my bike helmet?
• Do I really need to replace my helmet every 2-3 years if it hasn't been in a crash?
• How long does an unused helmet keep for?

I hope this qualifies as a standalone question given that there are already a few but the cited ones are pretty old (between 6 and 13 years) and feature some contradicting standpoints, for example the 5-year rule vs. the study quoted in #3 that showed 5 years are not enough to impact the structure as much so that a helmet would fail a crash test...

Question complex #1 (lifetime): Mine is used for about 3 years and the manufacturing date states mid-2018 (reaching 5+ years), which date should I take into consideration, here?

Should one be more cautious when buying helmets of the shelf because it may already have 1-2 years of life before you actually ride it, effectively reducing its active usage duration? Do the 5 years include use and exposure to sweat and sunlight or is this strictly from a material age standpoint? (plastic shell, styrofoam core, glue, etc...)

Question complex #2 (damage replacement): Is every crack in the styrofoam an instant write-off? I'm aware that this weakens the structure, indeed, but is such damage always considered a reason to replace it?

Mine definitely didn't suffer a crash and no sign of shell and core separating, over the course of three years, I can't rule out that it hasn't taken a minor fall (like from my sofa when dressing up for a ride) but nothing I would consider a "oh-no" situation that made me think I should not have dropped it.

However, mine has a crack at the front - there is no adjacent damage on the shell but it is a crack, nevertheless. It might have been there for a while but I just noticed recently when I took out the padding for a wash.

My anticipation is that in my case, the combination of borderline age and damage will lead to the suggestion Get a new helmet (and I probably will because it is hard to find pads for the Cosmic Pro) but I would still be interested in some thoughts, experience and resources on the topic.

Answer 1

Your foam is cracked, and it may not be able to perform as designed in the event of an impact.

Replace that helmet at the first possible opportunity and refrain from riding with that helmet.

It pays to cast an eye over your gear periodically, to look for exactly this kind of subtle damage. Perhaps monthly, or whenever doing maintenance, whatever semi-regular period helps.

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1. A helmet will not noticeably deteriorate between manufacture and sale, barring damage while shipping like being dropped. So I'd not be concerned about a new-old-stock helmet as long as its not visibly damaged or faded.

2. Yes, a crack all the way through the foam like that is instant cause for retirement. That crack is right at the front, probably the most likely part to strike something in an accident, more likely than the side or rear or top.

Lifespan: A helmet that gets fairly minimal usage may have no visible damage after decades, whereas one that is worn daily may start showing damage much quicker, so there's no hard-and-fast time limit. A year of commuting may equate to 7 years of saturday rides.

If the owner is the kind of rider who throws things around then it'll acquire damage quicker, and commuting is always harder on gear.

Likewise, simply hanging the helmet on a bike or hook is slightly more likely to be dropped compared to clicking the strap/binding closed around a loop.

Aside - the hard plastic outer shell is an integral part of the design, enabling "sliding-over-the-ground" instead of "digging in". If that's damaged, replace helmet ASAP.

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I would say any regularly-worn helmet should be replaced at about 8 years at most, and sooner if the retention system is damaged/worn or if any parts start falling off or cracking. By that age the linings and padding will be breaking down, and the straps will have suffered some oxidising.

Personally, I've retired 4 helmets due to age, and one at ~2 years due to collision. My first helmet was in 1987, so that's 36 years or about 8.5 years per helmet (excluding collision)

Answer 2

I wear a Giro helmet and according to their website:

How often should a helmet be replaced? Is it OK to use old helmets? We make a general recommendation of replacing a helmet every three to five (3-5) years depending on use and handling. This is based on observation of the average user, and factors like wear over time, weather, handling, the potential for degradation from personal care products like sunscreen or bug spray, and the simple fact that helmets do improve over time. While helmets kept in good condition can provide protective capability beyond the 3-5 year recommended lifespan, it’s also true that they can degrade over time. This is why we recommend replacing the helmet within this regular interval. If you fall and the helmet is impacted, you should have the helmet inspected or replace the helmet immediately, even if no damage is visible. The reason is that helmet liners are made to absorb energy from impacts and they do this through their own degradation or destruction – like an airbag in a car. If the liner is compromised from an impact or other factors, it may not offer the full protective capability it was designed to provide.

From their FAQs page at https://www.giro.com/frequently-asked-questions.html

I personally would follow the manufacturer's recommendations.

Answer 3

I wouldn't be as worried about the crack in the styrofoam - the foam has no structural role per se, its purpose is only to provide resistance to squishing, i.e. pure compressive force, and a crack doesn't much reduce this capability. What is much more worrying is that the crack also goes into the shell, because the shell is structural. The shell is not only there to protect the foam from abrasion, but more importantly to spread impact forces over a large area so the foam can absorb them. Even a small crack stops this from working properly, and then the edges can easily cut through the foam.

Of course, that's not to say a helmet is necessarily alright if only the foam is cracked but no crack visible in the shell. The event that cracked the foam would likely have caused other damage too. In terms of the foam itself, the worst problem is if it has been squished once because that will reduce its resistance to squishing another time. But this should be judged based on your knowledge of what the helmet has gone through, more than how the foam looks.

My anecdotal experience is that good-quality helmets can still do some of their job after having survided a crash impact. Once I had a pretty hefty crash, hit my forehead on a stone while riding downhill MTB. Official advice would probably have been to discard the helmet (Uvex), but after inspection (no cracks, only scratches and visor damage) I decided to continue wearing the helmet for normal road usage. What do you know, I had another hit on the forehead with the same helmet, and it protected me just fine. It did crack that time though, so I then trashed it. The second crash was definitely less severe than the first though, so I guess that demonstrates that helmet wasn't 100% fit at that point anymore.