We hear stuff like this all the time: replace your helmet every three years, or every five years. Dropped your helmet? Replace it. Don’t place your helmet on your mirror. Don’t use chemicals to clean your helmet. Don’t paint your helmet. Don’t look at your helmet wrong.

So many warnings! Helmets are supposed to protect our heads in a crash, but according to the conventional wisdom, well, they sound downright fragile! How much of this advice is from people who know what they’re talking about, based on facts?

We wanted to find out how well helmets hold up in normal, day-to-day life, and what better way to do this than to collect a bunch of helmets and bash them in a lab. The trick would be getting someone reputable to let us into their labs so we could do legitimate tests.

Methodology

We’re not scientists. Not even close. But saying “methodology” makes it sound like we had some kind of plan, and we did.

  1. Document replacement and care recommendations from authoritative sources.
  2. Trick someone with a testing lab into letting us bash some helmets in said lab.
  3. Get some helmets to bash.
  4. Bash ‘em!

Step 1: Our first step was finding out what some of the major players say about helmet replacement and care.

The SNELL Memorial Foundation has a question in their FAQ dedicated to this, entitled “Why should you replace your helmet every five years?” The answer: “The recommendation for five-year helmet replacement is a judgment call stemming from a prudent safety philosophy.” In a nutshell, chemicals, hair oils, and other “commonly encountered materials” can degrade the performance of helmets, so it makes sense to replace your helmet periodically, just to be safe. That’s what helmets are about, right?

SNELL answers the question of “I dropped my helmet! Do I have to go buy a new one?” with “probably not,” explaining that helmets, while single-use devices, really only suffer damage when they hit something with a head inside.

SNELL also says don’t clean the inside or outside of your helmet with “any chemical cleaning products.”

Arai recommends you replace your helmet after five years of use or seven years after its manufacture date. They offer no specific recommendation on dropped helmets.

Arai also cautions against cleaning with chemicals, saying “Use no cleaning products, no matter how mild you may think it is.”

Shoei recommends replacing your helmet five years after purchase. While there are no specific recommendations on what to do with a dropped helmet, Shoei does say to replace your helmet if “the helmet was subjected to an impact.”

Shoei says “commonly available… plastic cleaning agents” are ok for cleaning your helmet.

Bell is the most conservative in their estimation of helmet life, recommending replacement at just three years on their website, although their helmet manuals say five years. They offer no specific recommendation on dropped helmets.

Bell says mild soap (like dish soap) is ok for cleaning your helmet.

All three manufacturers noted above offer inspection of your helmet if you drop it or are in a minor crash. Shoei and Bell’s inspections are free—it’s unclear if Arai charges for this service.

So a lot of the conventional wisdom comes from authoritative voices. SNELL and helmet manufacturers seem to be united on the three to five year replacement recommendation, although recommendations on cleaning are a bit more diverse, and it’s unclear whether dropping your helmet is grounds for replacement all of the time.

Step 2: For a while, it really seemed like the project was going to die at this point—our phone calls and emails were getting us nowhere. But then Vice President of Corporate Affairs at Bell Sports offered us access to Bell’s lab and a technician, and our test was on! Even better, Bell’s lab is in Scotts Valley—basically down the street, at least compared to other labs.

Step 3: Now we need some helmets! We put the word out that we were looking for old helmets for a top-secret testing project, and began collecting donations. We asked for helmets that were over 5 years old, and not obviously destroyed. Over the course of a month or two, I met up with CityBike readers who wanted their old helmet to taste the anvil in the name of science (or something like that), and the pile of helmets in my office quickly grew.

We ultimately collected over fifty helmets, ranging from high end and expensive to cheap and boring—an excellent sample set to start from!

Step 4: Testing day!

We arrive at Bell Labs and with the help of Thom and a large cart, drag our helmets into the lab. Thom gives us a brief tour of the facility, including a room full of CNC machinery for prototyping, and we get down to business—basically sorting and labeling all the helmets according to production date, size, and original standard. Our plan is to test our helmets against the standard they were originally certified to. Since we have so many helmets, we narrow it down to a few of each size, settling on seventeen representative helmets.

Our technician, Rafael, walks us through the testing process, and draws a sample test line on one of our helmets. This line establishes the testing area on the helmet, in accordance with the standard the helmet is to be tested against. There’s an incredible amount of prep work involved in the testing—obviously, we don’t get a second chance at each helmet.

The testing goes something like this: the helmets get two hits in each test spot, and we test side, front and back impact, to see how much energy is transmitted to the headform “wearing” the helmet. In a crash, the headform would be you. We’re focusing on the impact component of the testing, since we’re primarily concerned with the effects of age and environmental factors on the EPS liners. This means we’re not testing how well the retention systems keep the helmet on the test headform.

We give each helmet an ID, partly because this makes it easier to track the data, partly because we don’t want to tell you guys the brands and models of these helmets, and partly because, like saying “methodology,” using IDs makes us feel smart and scientific-like.

Each test results in a spreadsheet file with a pile of data in it—there are a lot of complexities in what is measured and what the results mean, but we’ve boiled it down to simple pass/fail measures here, as the whole dataset would take up every page of this issue!

Our first helmet finally hits the anvil, and cracks pretty badly. However, the energy is correctly dissipated, and the helmet passes—the helmet sacrificed to save the head inside. This is repeated throughout the day—some of the helmets don’t appear to hold up real well, but they do their job.

We get our first bad failure a few helmets in, on the second hit to the front of a helmet. Thom and Rafael look at the data on-screen for a moment, and Thom says grimly, “that’s a fatality.” Yikes.

Throughout the day, we’re surprised at the low number of failures we’re seeing. A couple particularly ancient lids pass all tests, no problem. Here’s the thing though—remember that we’re testing our helmets against the standards they were originally certified to, not current standards. Also, just because a ten year old helmet passes, that doesn’t mean that it wouldn’t have done a better job of protecting your noggin when it was just a couple years old.

We don’t have any definitive background info on most of the helmets that failed, but here’s an interesting tidbit: 115, the 1993 helmet that failed 4 out of 6 tests, was an old stock, brand new helmet that had been hanging around a showroom for 20 years. It seems clear that environmental factors wreaked havoc on this one. Also, it’s worth noting that most of the failed helmets were “premium” brands.

Motorcycle Helmet Testing Results

DOT Helmets, by Helmet ID and Impact Area

Impact/ID 109 110 111 113 114 116
Front 1 Pass Pass Pass Pass Pass Pass
Front 2 Pass Pass Pass Pass Pass Fail
Side 1 Pass Pass Pass Pass Pass Pass
Side 2 Pass Pass Pass Pass Pass Pass
Rear 1 Pass Pass Pass Pass Pass Pass
Rear 2 Pass Pass Pass Pass Pass Pass
Production Year 2008 2009 1998 2003 1980 2009

SNELL Helmets, by Helmet ID and Impact Area

Impact/ID 105 106 107 104 103 101 102 117 115 108 112
Front 1 Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass
Front 2 Pass Pass Pass Fail Pass Pass Fail Pass Fail Pass Pass
Side 1 Pass Pass Pass Pass Pass Pass Pass Pass Fail Pass Pass
Side 2 Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass
Rear 1 Pass Pass Pass Pass Pass Pass Pass Pass Fail Pass Pass
Rear 2 Pass Pass Pass Pass Pass Pass Pass Pass Fail Pass Pass
Production Year 1991 2007 2004 2000 2008 2011 2008 2008 1993 2005 2005

Conclusions

We shouldn’t even use the word “conclusions,” really—or rather, we should leave it you, the reader, to draw your own. Of our seventeen “mature” helmets, just under 25% failed, but with our small dataset, we can’t identify factors such as the effect of age alone on likelihood of helmet failure. That, and lack of a controlled environment for the helmets to age in, are the primary problems with our test.

To do this right, we’d need new old stock, in box, “control” helmets for each candidate, so we could test helmets that have been exposed to all sorts of environmental factors against “sheltered” helmets, and we’d need to test at more time periods than just “really old.” Barring that, we’d at least like to know the full background on each candidate. But we’ll have to do with this small test for now, so here’s what we think our limited results mean, in general terms.

1. Take care of your helmet, and this includes trying to shelter it from harmful chemicals like car exhaust and excessive hair products. In other words, your garage is probably not the place to store your helmet, and stop putting all that crap in your hair. It’s worth noting that all of the failures appeared to be in good physical shape, another potential indicator of the power of environmental factors in helmet lifetime.

2. Replace your helmet when it needs to be replaced, like when it gets too gross from sweat, or damaged in a crash, or because you feel like it’s time.

Here’s what we’re not saying. We’re not saying you shouldn’t replace your helmet at five years, or if you drop it a bunch of times. Sure, there’s evidence that lots of helmets go well past five years and still work just fine. On the other hand, a near 25% failure rate is not a real solid bet when we’re talking about brain injury, and five years seems like a good, if a bit arbitrary, helmet replacement interval.

Whatever conclusions you draw from this, remember: brains are important—take care of your helmet so it can take care of your head.

This story originally appeared in our November 2014 issue.

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