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> I bought a Giro Atmos over a decade ago and never needed to upgrade... I’m sure you’ve heard this but they say to replace a helmet every two-three years even

> I bought a Giro Atmos over a decade ago and never needed to upgrade... I’m sure you’ve heard this but they say to replace a helmet every two-three years even if it hasn’t been in a crash. It’s up to you whether you think that makes sense, but I’d sooner believe it than not.

TheSpiceIsLife 7y ago
It'd be hard to miss the potential for that to be marketing-speak for "buy more helmets more often", especially given the context of the comment you replied to.
- adrianN 7y ago
  I've had old helmets develop cracks spontaneously so this is marketing that I tend to believe.
  - TheSpiceIsLife 7y ago
    By old do you mean two years or twenty?
    - adrianN 7y ago
      I think that helmet was less than four years old. And it wasn't a cheap one either.
      - jacquesm 7y ago
        That's a warranty issue more than a reason to buy another one of the same brand.
Cyclone_ 7y ago
I've raced for about 6 years now and have not replaced my tri helmet, but have replaced the one I use when I'm on my road bike (only because it broke in a crash), where did you hear that you should replace the helmet that frequently?
- Alex3917 7y ago
  Any safety equipment made from plastic needs to be replaced every 3 - 5 years because it's weakened by light and air. Same for rock climbing ropes, life jackets, children's car seats, etc.
  - semi-extrinsic 7y ago
    The official guidance for life jackets is 10 years. https://www.secumar.com/en/servicing/ https://www.secumar.com/en/servicing/ For bike helmets, independent safety labs have actually done the science and found no measurable deterioration in impact testing nor material properties with helmets as much as 26 years old. (Link to journal paper at end of summary linked below.) https://helmets.org/up1505a.htm https://helmets.org/up1505a.htm
  - usrusr 7y ago
    Rock climbing ropes have very clear performance metrics. "Hard hat" style helmets are similar, they are made to protect from falling projectiles like tools or rocks and must not break. Bicycle helmets just add a few mm of valuable deceleration distance in the best case, that's all they do apart from protecting from purely cosmetical abrasions. The maximum amount of extra deceleration distance is provided at one very specific kind of impact. When the material properties change, the maximum will be achieved at a different impact. But you cannot predict which one you will have that one time when you actually use the helmet. The old one might be better or worse, nobody knows. If manufacturers knew exactly what would eventually hit you, lots of engineering could be applied to precisely tune the helmet to that impact, but they don't know so they cannot do that. So all the engineering goes into achieving comfort while hitting regulation targets and into marketing features that only need to appeal to "common sense". There is no engineering at all going into the main purpose. Even aerodynamics, a clearly defined performance metric orthogonal to protection, is just barely starting to move on from hand-wavey "fast looks" to actual engineering.
kevin_thibedeau 7y ago
And your mattress doubles in weight every eight years.... That is just a way to sell more product by shaming people into "being safe". Uncrashed styrofoam doesn't stop being effective and turn into a pumpkin after two years. But you can double revenue if you can halve the replacement cycle.
- benj111 7y ago
  "And your mattress doubles in weight every eight years" I'd never heard that one before. https://www.snopes.com/fact-check/mattresses-double-weight-every-10-years/ https://www.snopes.com/fact-check/mattresses-double-weight-e...
- GordonS 7y ago
  > That is just a way to sell more product by shaming people into "being safe". The cynic part of me agrees, but is it though? Some plastics seem to get "stressed" over time, especially if under sunlight (not sure if it's the temperature or UV that's the issue) - I wonder if that's part of the concern here?
- ISL 7y ago
  As the plasticizer leaves plastics, it becomes embrittled. You want the EPS to crush smoothly -- if it cracks and displaces, it will not be in place to absorb energy and cushion the impact further. We replace our bike helmets every ~6 yr. Source: Have listened to the crackle of decade-old plastic kayaking helmets under tensile/compressive stress and watched them shatter like glass after impact with a concrete floor. New helmets from the same manufacturer did neither.
- stef25 7y ago
  Guy in a motorbike shop told me it's UV that makes styrofoam lose its useful properties, a quick Google seemed to confirm that.
  - lm28469 7y ago
    I've never seen any motorcycle helmet with exposed styrofoam though.
gambiting 7y ago
>>I’m sure you’ve heard this but they say to replace a helmet every two-three years even if it hasn’t been in a crash. Just like the sofa store tells me that ideally you need to flip all cushions on my sofa every day? It's a load of marketing nonsense.
rasebo 7y ago
For motorcycle helmets the replacement interval is 5 years for most manufacturers. Why are bicycle helmets supposed to replaced more often?
- zachrose 7y ago
  It might be five years, I’m just saying I think there is a recommendation and I think it’s less than 10.
- logfromblammo 7y ago
  Motorcycle helmets generally have a thicker, smooth exterior shell that better protects the foamed plastic under it from UV and O2 degradation. With cheaper bike helmets, they often have more ventilation holes, and you can usually see the formed EPS. That said, you could just put zinc oxide sunblock on your helmet and then protect the UV-blocking layer with a spray urethane top-coat, and thereby extend the useful lifespan of your helmet by years. Can't really do much about O2 damage or migration of plasticizers, though, unless you want to freeze your helmet any time you're not wearing it. Keeping it in an air-conditioned interior room rather than a hot garage or bike locker might help. EPS can last quite a while when buried, where it is protected from UV, excessive O2, or heat extremes, but I wouldn't entirely trust an EPS helmet beyond 10 years. It's not so much that EPS can't last that long, but that you can't guarantee that it hasn't encountered environmental conditions that would result in degradation over longer time spans. Better a 10-year-old helmet than no helmet, though. There's no excuse for doing that when municipalities sometimes just give away free (to the recipient) bicycle helmets, maybe with sponsorship by an insurer or National Safety Council or similar organization.
  - DanBC 7y ago
    > That said, you could just put zinc oxide sunblock on your helmet and then protect the UV-blocking layer with a spray urethane top-coat, and thereby extend the useful lifespan of your helmet by years. Please don't fuck about with safety critical equipment.
    - 7y ago

TheSpiceIsLife 7y ago

It'd be hard to miss the potential for that to be marketing-speak for "buy more helmets more often", especially given the context of the comment you replied to.

adrianN 7y ago
I've had old helmets develop cracks spontaneously so this is marketing that I tend to believe.
- TheSpiceIsLife 7y ago
  By old do you mean two years or twenty?
  - adrianN 7y ago
    I think that helmet was less than four years old. And it wasn't a cheap one either.
    - jacquesm 7y ago
      That's a warranty issue more than a reason to buy another one of the same brand.

Cyclone_ 7y ago

I've raced for about 6 years now and have not replaced my tri helmet, but have replaced the one I use when I'm on my road bike (only because it broke in a crash), where did you hear that you should replace the helmet that frequently?

Alex3917 7y ago
Any safety equipment made from plastic needs to be replaced every 3 - 5 years because it's weakened by light and air. Same for rock climbing ropes, life jackets, children's car seats, etc.
- semi-extrinsic 7y ago
  The official guidance for life jackets is 10 years. https://www.secumar.com/en/servicing/ https://www.secumar.com/en/servicing/ For bike helmets, independent safety labs have actually done the science and found no measurable deterioration in impact testing nor material properties with helmets as much as 26 years old. (Link to journal paper at end of summary linked below.) https://helmets.org/up1505a.htm https://helmets.org/up1505a.htm
- usrusr 7y ago
  Rock climbing ropes have very clear performance metrics. "Hard hat" style helmets are similar, they are made to protect from falling projectiles like tools or rocks and must not break. Bicycle helmets just add a few mm of valuable deceleration distance in the best case, that's all they do apart from protecting from purely cosmetical abrasions. The maximum amount of extra deceleration distance is provided at one very specific kind of impact. When the material properties change, the maximum will be achieved at a different impact. But you cannot predict which one you will have that one time when you actually use the helmet. The old one might be better or worse, nobody knows. If manufacturers knew exactly what would eventually hit you, lots of engineering could be applied to precisely tune the helmet to that impact, but they don't know so they cannot do that. So all the engineering goes into achieving comfort while hitting regulation targets and into marketing features that only need to appeal to "common sense". There is no engineering at all going into the main purpose. Even aerodynamics, a clearly defined performance metric orthogonal to protection, is just barely starting to move on from hand-wavey "fast looks" to actual engineering.

kevin_thibedeau 7y ago

And your mattress doubles in weight every eight years.... That is just a way to sell more product by shaming people into "being safe". Uncrashed styrofoam doesn't stop being effective and turn into a pumpkin after two years. But you can double revenue if you can halve the replacement cycle.

benj111 7y ago
"And your mattress doubles in weight every eight years" I'd never heard that one before. https://www.snopes.com/fact-check/mattresses-double-weight-every-10-years/ https://www.snopes.com/fact-check/mattresses-double-weight-e...
GordonS 7y ago
> That is just a way to sell more product by shaming people into "being safe". The cynic part of me agrees, but is it though? Some plastics seem to get "stressed" over time, especially if under sunlight (not sure if it's the temperature or UV that's the issue) - I wonder if that's part of the concern here?
ISL 7y ago
As the plasticizer leaves plastics, it becomes embrittled. You want the EPS to crush smoothly -- if it cracks and displaces, it will not be in place to absorb energy and cushion the impact further. We replace our bike helmets every ~6 yr. Source: Have listened to the crackle of decade-old plastic kayaking helmets under tensile/compressive stress and watched them shatter like glass after impact with a concrete floor. New helmets from the same manufacturer did neither.
stef25 7y ago
Guy in a motorbike shop told me it's UV that makes styrofoam lose its useful properties, a quick Google seemed to confirm that.
- lm28469 7y ago
  I've never seen any motorcycle helmet with exposed styrofoam though.

gambiting 7y ago

>>I’m sure you’ve heard this but they say to replace a helmet every two-three years even if it hasn’t been in a crash. Just like the sofa store tells me that ideally you need to flip all cushions on my sofa every day? It's a load of marketing nonsense.

rasebo 7y ago

For motorcycle helmets the replacement interval is 5 years for most manufacturers. Why are bicycle helmets supposed to replaced more often?

zachrose 7y ago
It might be five years, I’m just saying I think there is a recommendation and I think it’s less than 10.
logfromblammo 7y ago
Motorcycle helmets generally have a thicker, smooth exterior shell that better protects the foamed plastic under it from UV and O2 degradation. With cheaper bike helmets, they often have more ventilation holes, and you can usually see the formed EPS. That said, you could just put zinc oxide sunblock on your helmet and then protect the UV-blocking layer with a spray urethane top-coat, and thereby extend the useful lifespan of your helmet by years. Can't really do much about O2 damage or migration of plasticizers, though, unless you want to freeze your helmet any time you're not wearing it. Keeping it in an air-conditioned interior room rather than a hot garage or bike locker might help. EPS can last quite a while when buried, where it is protected from UV, excessive O2, or heat extremes, but I wouldn't entirely trust an EPS helmet beyond 10 years. It's not so much that EPS can't last that long, but that you can't guarantee that it hasn't encountered environmental conditions that would result in degradation over longer time spans. Better a 10-year-old helmet than no helmet, though. There's no excuse for doing that when municipalities sometimes just give away free (to the recipient) bicycle helmets, maybe with sponsorship by an insurer or National Safety Council or similar organization.
- DanBC 7y ago
  > That said, you could just put zinc oxide sunblock on your helmet and then protect the UV-blocking layer with a spray urethane top-coat, and thereby extend the useful lifespan of your helmet by years. Please don't fuck about with safety critical equipment.
  - 7y ago