Category Archives: motorcycle helmet standards

Motorcycle helmet standards Dr. John Lloyd has served attorneys nationwide for 25+ years in biomechanics, human factors, helmet testing and motorcycle accident expert

What Every Rider Needs to Know About Motorcycle Helmets

I am a motorcycle enthusiast and a biomechanics researcher focusing on head and brain injury. Over the years I have performed more than 2600 helmet impact tests. The following are my take-away points for motorcyclists:

Lloyd-Biomechanics Motorcycle Helmets-Figure 2
  1. Helmets are the best protection we have against head and brain injuries. That said, standard certified motorcycle helmets are only 37-42% effective in preventing fatal head injuries. 
  2. Helmets are designed after ancient military helmets to serve as a second skull and thereby protect the head against focal injury.
  3. However, standard motorcycle helmets are not intended to protect against rotational brain injuries.
  4. There are two types of head and brain injuries, which are caused differently:
    • Translational (linear) forces cause focal injuries including cuts, bruises, and skull fractures.
    • Tangential forces cause rotational injuries including concussion, brain nerve damage, and brain bleeding.
    • Translational and tangential forces are generated in every impact
  5. Certified motorcycle helmets do a great job of protecting against focal head injuries.
  6. My research shows that DOT-certified motorcycle helmets reduce the risk and severity of focal injuries by 93 percent. 
  7. Novelty (non-certified) helmets do not offer any significant protection against focal injuries.
  8. It is therefore highly recommended that riders wear a certified motorcycle helmet at all times.
  9. Helmets that offer greater coverage, i.e. open-face (3/4) and full-face helmets, provide the best protection against focal injuries. However, the US DOT standard (FMVSS 218) [i] does not require impact testing of the chin bar, therefore there is no certified protection against facial injuries for full-face helmets that are only certified to the DOT standard.
  10. Generally, certified motorcycle helmets do not protect against rotational brain injuries. In fact, on average, a standard certified motorcycle helmet will actually increase the rider’s risk of concussion, nerve damage (axonal injury), and brain bleeding (subdural hemorrhage) by 19 percent, compared to an unhelmeted head impact.
  11. Rotational brain injuries are the cause of fatalities in two-thirds of all helmeted motorcycle deaths.
  12. It has been shown that, in general, larger and heavier helmets increase the risk of rotational brain injuries, including concussion, axonal injury, and brain bleeding because they generate greater impact-related rotational forces on the brain.
  13. So, what can a safety-minded rider do to minimize their risk?
  14. Revised motorcycle helmet standards are starting to look at brain injury risk. The new ECE 22.06 [ii] and Snell M2025 [iii] standards now measure the risk of rotational brain injury, though the passing threshold is 23% risk of neurologically devastating or potentially fatal rotation brain injury, at a moderate impact speed of 17.5 mph. 
  15. My recommendation is to choose a helmet that meets either the ECE 22.06 or Snell M2025 standard, in addition to whatever standard is mandated in your country.
  16. Choose a lighter, smaller helmet with the desired coverage over a larger, heavier helmet. Not only will this likely provide better protection against rotational brain injuries, but will also generate less wind resistance and be more comfortable on those longer rides.
  17. Consider helmets that incorporate new technologies that are intended to reduce the risk of rotational brain injuries.
  18. Don’t buy a helmet just based on looks, make an informed purchase based on fit and protective performance.
  19. What can motorcycle helmet manufacturer’s do to improve helmet performance?
  20. Current motorcycle helmet designs may be over-engineered to reduce translational forces that cause focal head injuries, resulting in helmets that are larger and heavier, thereby increasing the risk of rotational brain injuries, which are the primary cause of fatality in two-thirds of helmeted motorcycle crashes. Protection against focal injuries is important, but needs to be balanced against increased risk of rotational brain injuries. Manufacturers should evaluate materials that allow the development of smaller and lighter helmets.
  21. A meta-analysis is underway, comparing helmets intended for a variety of activities including motorcycling, skiing, bicycle, off-road, American football, ice hockey and military. Preliminary results suggest that helmets intended for other sports activities may outperform motorcycle helmets at similar impact speeds in terms of protection against both focal head injuries and rotational brain injuries

[i] U.S. Department of Transportation (2013) Federal Motor Carrier Safety Administration Standard No. 218, Motorcycle helmets. Washington, DC.

[ii] United Nations (2021). Uniform Provisions Concerning the Approval of: Protective Helmets, of their Visors and of their Accessories for Drivers and Passengers of Motorcycles and Mopeds. Regulation No. 22-06

[iii] Snell Memorial Foundation. (2024). Standard for Protective Headgear for use with Motorcycles and Other Motorized Vehicles. M2025

Motorcycle Helmet Standards

Motorcycle helmets were originally developed in the early 20th century and, like most helmets, are modeled after military helmets, the purpose of which is to protect against penetrating head injury. The modern motorcycle helmet, with a hard outer shell and rigid expanded polystyrene (EPS) liner was actually introduced over 60 years ago. The outer shell serves as a second skull, dispersing the impact force over a wider surface area, while the inner shell compresses in an attempt to reduce translational forces. A mechanism to mitigate tangential forces is absent. Since the liner fills the entire inner surface of the shell, tangential forces cannot be absorbed and are transmitted directly to the head and brain. Motorcycle helmet standards focus on reducing the effect of linear impact forces by dropping them from a given height onto an anvil and measuring the resultant peak linear acceleration.

Motorcycle Helmet Standards

In motorcycle helmet testing, the risk of impact loading injuries, such as skull fractures, can be determined by measuring linear accelerations experienced by a surrogate head form in response to impact. Whereas risk of impulse or inertial loading injuries, such as concussion, axonal injury and subdural hematoma can be quantified by measuring impact-related angular accelerations at the center of mass of a test head form.

Unfortunately, the evolution of motorcycle helmet design is not driven by advances in scientific knowledge, but rather by the need to meet applicable testing standards. In the United States, standards include the federal motor vehicle safety standard (FMVSS) #218, commonly known as the DOT motorcycle helmet testing standards, and Snell M2015, while ECE 22.05 and BSI 6658 were adopted in European countries. Test procedures involve dropping a helmeted head form onto various steel anvils at impact velocities ranging from only 5.0 to 7.75 m/s (11-17 mph). Pass/fail is based on the ability of the helmet to provide protection against forces associated with linear acceleration in response to impact.

John Lloyd expert witness motorcycle helmet standardsCurrent motorcycle helmet testing standards do not incorporate measures of angular acceleration and therefore fail to assess whether helmets offer protection against catastrophic brain injuries. The omission of this critical measure is reflected epidemiologically in the disproportion of closed head injuries in fatal motorcycle accidents.

Helmeted Motorcyclist Fatality

Two helmeted motorcyclist were traveling on a rural state road when a tractor-trailer driver failed to see the bikes and made a left turn in front of them to enter a truck stop. The rider in the right track had little time to respond and collided head first into the box trailer. He was pronounced deceased at the scene.

Lloyd helmeted motorcycle case

The helmeted motorcyclist was wearing a non-compliant or ‘novelty’ helmet, which did not meet DOT motorcycle helmet standards (FMVSS 218). Opposing counsel claimed that had the biker been wearing a DOT-certified motorcycle helmet he may have survived the impact.

novelty motorcycle helmet shell
novelty motorcycle helmet liner

Motorcycle helmet expert, Dr. John Lloyd, was retained to evaluate and compare the protective performance of DOT-certified and novelty motorcycle helmets.

Based on a comprehensive motorcycle accident reconstruction it was determined that the impact speed of the rider was 45 to 50 miles per hour. Motorcycle helmet certification tests typically involve impact speeds of 13-17 miles per hour. Therefore a dedicated apparatus was constructed to generate higher impact speeds. Using a force-balanced twin pendulum apparatus, Dr. Lloyd was able to generate head impact speeds similar to those specific to the subject crash, yet preserve the standard DOT test methodology, thereby avoiding a Daubert challenge.

Eight DOT and non-DOT helmets were purchased for this study. Each was impacted once in the frontal region while fitted to an instrumented crash test dummy head. High speed data and video were acquired for each test.

Results demonstrate that, although the tested DOT-certified motorcycle helmets outperformed the tested novelty helmets, neither would provide adequate protection against head injuries, such as skull fractures, contusions and lacerations, or brain injuries, including hemorrhages or axonal injury in an impact of this magnitude.

helmeted motorcyclist head injury
helmeted motorcyclist brain injury

Dr. Lloyd’s prior published motorcycle helmet studies demonstrate that while DOT-certified motorcycle helmets can reduce the risk of traumatic head injuries, typical helmets do not afford any protection against acute brain injury.

Testing Proves Motorcycle Helmets Provide Inadequate Protection Against TBI

Motorcycle accident victims account for more than 340,000 fatalities annually, with the United States ranking 8th highest worldwide in the number of motorcycle accident deaths. 75% of all fatal motorcycle accidents involve brain injury, with rotational forces acting on the brain the primary cause of mortality. Current motorcycle helmets are effective at reducing head injuries associated with blunt impact. However, the mechanism of traumatic brain injury is biomechanically very different.

Samples of 9 motorcycle helmet models, representing full-face, three-quarter and shorty designs were evaluated. Helmets, fitted to an instrumented Hybrid III head and neck, were dropped at 13 mph in accordance with DOT motorcycle helmet testing standards.motorcycle helmets test

Results show that, on average, there is a 67% risk of concussion and a 10% probability of severe or fatal brain injury associated with a relatively minor 13mph helmeted head impact.

motorcycle helmets test results

In conclusion, motorcycle helmets provide inadequate protection against concussion and severe traumatic brain injury associated with even relatively minor head impact