Snell vs DOT: Which Standard To Go By?

One thing that continues to confound many riders to this day are the varying motorcycle helmet testing standards and how they affect the safety ratings of helmets.

Snell and DOT (Department of Transportation) are the two most well-known, but what criteria do they test helmets by and how do they compare?​

One pearl of antique wisdom claims that, DOT helmets were generally considered more shock-absorbent while Snell helmets were tested to be more shock-resistant, but is this still the case?

Looking at how each goes about their testing reveals some interesting information.

Testing Procedures

The immediate place to look for a difference would be the actual tests used to grade helmets in each standard.

According to the Snell Memorial Foundation website, both Snell and DOT tests involve dropping a replica head outfitted with sensors and placed inside a helmet against shaped anvils (flat, hemisphere, curbstone, roll bar, and edge) at high speeds to measure the g-forces.

The impact tests are repeated multiple times to and see if the helmet can withstand repeated blows to the same area.

Both standards systems include retention tests to determine how well the helmet can remain on a rider's head during an incident. Both Snell and DOT use what is known as the roll-off test, wherein they attempt to separate the helmet from the replica head by rolling it off with a weight.​

Both standards require penetration tests to measure the resistance a helmet has to piercing. Both Snell and DOT tests involve a 10-ounce weight and a guided fall from 9.8 feet, and both tests register a fail result if the striking weight makes contact with the replica head.

In these regards at least, both the DOT and Snell standards are quite similar. Where, then, do they begin to deviate? Additional tests done by Snell are what make their certified helmets exceed the standards set by DOT.

Firstly, the DOT standard only includes the roll-off test. Snell standards also include a dynamic retention test, which involves using falling weights to see if a helmet might pop off of a rider's head due to downward force.

Snell employs a chin bar test for full face helmets, which involves dropping an 11-pound weight onto the chin bar from fixed heights, then measuring any deformation that occurs to the chin bar.

Snell also tests the face shields of full face helmets by shooting at them with soft lead pellets from an air rifle. The pellets travel at about 310 MPH and helmets fail if the face shield is penetrated or any deformation on the face shield exceeds 0.01 inches.​

Impact Analysis

Both testing methods make use of accelerometers to determine how quickly the helmet ceases to move during the guided fall in the impact test. Whereas DOT allows for a peak acceleration of up to 400Gs, whereas the Snell standard is only up to 300Gs.

The contention that Snell has with the DOT standard are the limitations they place on the duration of acceleration during testing. The criteria are considered dated, as they were taken from a different standard that involved a different testing device all the way back in 1972.​

Enforcement of Standards

As if that wasn't enough, the DOT has long had a problem with counterfeit labeling. Though the DOT standard is set by and required by the National Highway Safety Administration (NHTSA), they don't test the helmets against the DOT standards.

The burden to test helmets falls on the manufacturer, but they don't have to test the helmets and can just self-certify without doing any testing at all. DOT has attempted to standardize the look of their label to reduce counterfeits, with some success.

There is a penalty for selling defective merchandise, $5,000 for every non-compliant helmet discovered, but the NHTSA only acquires samples to test at random. This makes enforcement of the rule spotty at best.

Compare the Snell standard, which manufacturers like Bell voluntarily submit to in an effort to prove the safety of their helmets. It is done by Snell technicians, at Snell labs. Snell also buys samples from manufacturers on a regular basis to perform follow-up testing.

In addition, many Snell certified helmets also meet or exceed the requirements set by DOT.​

The Bottom Line

It's a hotly debated topic, and while some claim that the DOT testing standards are too minimal and that the “honor system” promotes misuse by manufacturers, the opposing argument is that the Snell test is administered differently enough to render it invalid.

Moreover, there is a view that the certification is not really what matters, as a controlled testing environment is different than the actual conditions faced on the road, and helmets can be constructed to conform to the standards without actually performing well out in the field.

Still, testing is valuable in determining the potential of a helmet, and the most extensive standard is Snell. This, in general, implies that you'll get a safer helmet when choosing a helmet that is Snell certified.

If conforming to standards is a chief concern, you can always go with helmets such as the Bell Vortex, to make sure you have both DOT and Snell compliance covered.

Have any questions? Want to let us know which helmet you prefer? Leave a message in the comments below!

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