Snell Helmet Guidelines

The Snell Memorial Foundation is a not-for-profit organization dedicated to research, education, testing and development of helmet safety standards. Since its founding in 1957, Snell has been a leader in helmet safety in the United States and around the world.

The Leader in Helmet Safety Testing for 40 Years

Though the name William "Pete" Snell may not be familiar, anyone who enjoys motorcycling, automotive racing, skiing, horseback riding, bicycling, in-line skating and/or skateboarding, they should know about the Snell Memorial Foundation.

As a memorial to Pete, a group of scientists, physicians, racing colleagues and friends teamed together in a dedicated effort to promote research, education, testing and development of standards geared to improve the effectiveness of automotive racing helmets. Through their work, the Snell Memorial Foundation was established in 1957. The Foundation has a Board of Directors that oversee the Foundation's operations. The board is comprised of Medical Doctors and Ph. Ded research scientists and engineers, all of which have distinguished themselves in the areas of safety and/or head injury.

Today, Snell is known for its ongoing work in setting, maintaining and continually upgrading the most authoritative helmet standards in the U.S. and throughout the world. Snell tests thousands of helmets each year and maintains its objectivity by remaining independent of helmet manufacturers, as well as local and national governments. Its state-of-the-art testing facility is located in North Highlands California, just outside Sacarmento.

Helmets meeting Snell Standards provide the highest level of protection available. Snell Standards significantly surpass those set by the U.S. Department of Transportation (DOT), the American National Standards Institute (ANSI), the American Society of Testing Materials (ASTM) and the U.S. Consumer Products Safety Commission's 16 CFR Part 1203.

In order to continuously monitor the quality of helmets being sold to the public, Snell purchases and tests samples of currently certified helmets from the marketplace. These helmets are tested only in Snell labs by Snell technicians. Should a currently certified helmet fail, the helmet manufacturer must take corrective action to Snell's satisfaction.

To take advantage of technical and research development and to provide the highest degree of safety to consumers, Snell Standards are updated about every five years. Updates are based on new Scientific Research and available manufacturing technology.
The Snell safety helmet standards are recognized in the U.S. and worldwide through support of the following organizations:

Snell Helmet Testing Programs

Snell Memorial Foundation has one of the most advanced and busiest helmet testing facilities in the world. Snell's California helmet testing laboratory is the one of the few in the United States accredited to ISO 17025 by the American Association for Laboratory Accreditation (A2LA).

How Helmets are Tested in Snell Labs
Before a helmet can be Snell-certified, it is tested in Snell's state-of-the- art facilities. Snell technicians conduct a variety of tests to determine the helmet's performance and ability to stay on the head in different weather conditions -- rain, hot, cold, etc. Depending on the application, the helmet must pass all or some of the following tests:

Impact Test
This test involves a series of controlled impacts where a helmet is positioned on a metal head form and then dropped in a guided fall onto various steel test anvils (Flat, Hemisphere, Kurbstone, Roll_bar, edge or a horseshoe type) which simulate different impact surfaces. (See below for the picture). The head forms are instrumented with an accelerometer to measure peak G force or acceleration which is measured in "G"ravitational units. The impact energy (drop height and mass), or how hard the helmets are impacted is unique to each standard. However, if in any valid test the peak acceleration imparted to the head form exceeds 300 G's, the helmet is rejected.
Positional Stability (Roll-Off) Test

A head form is mounted on a stand so that it points face downward at an angle of 135 degrees. The helmet is placed on the head form and the straps and buckles adjusted to obtain a "best fit". A wire rope is hooked to the rear edge of the helmet and brought forward so that its free end runs across the helmet and downward towards the floor. The free end of the rope has a mechanical stop with a 4 kg weight resting on the stop. The weight is raised to a 0.6 meter height and dropped to the stop. The resulting shock places a rotational load on the helmet. The helmet may be shifted, but must not roll off the head form. Next the head form is rotated 180 degrees, the helmet adjusted, and tested with the wire rope hooked to the front edge of the helmet. As in the first case, the helmet may be shifted but must not roll off the head form.
Dynamic Retention Test

The helmet is placed on a head form and the chin strap fastened under a device approximating the contour of the jaw. The jaw piece is loaded with a 23 kg weight for approximately one minute. The retention system is tested by simultaneously removing the 23 kg weight and applying a 38 kg mass in an abrupt guided fall. The retention system fails if it cannot support the mechanical loads or if the maximum instantaneous deflection (stretch) of the retention system exceeds 30 mm. Drop heights for the 38 kg mass are different for each standard, however the mechanism and failure criteria are similar for other types of headgear.
Chin Bar Test

The chin bar test applies to full face motorcycle, special application racing and kart racing helmets. The helmet is affixed to a rigid base with the chin bar facing upward. A 5 kg weight is dropped through a guided fall to strike the central portion of the chin bar. Maximum downward deflection of the chin bar must not exceed the stated distance.

Shell Penetration Test
The shell penetration test applies to motorcycle, special application racing, kart racing, skiing and equestrian helmets. The helmet is affixed to a rigid base. A 3 kg sharply pointed striker is dropped in a guided fall onto the helmet from a prescribed height. The test striker must not penetrate the helmet or even achieve momentary contact with the head form.

Faceshield Penetration Test
The face shield penetration test applies to full face motorcycle, special application racing and kart racing helmets. The face shield is affixed to the helmet and shot along the center line in three separate places with an air rifle using a sharp soft lead pellet. Pellet speed will be approximately 500 kph. For the both types of shield the pellet must not penetrate, and for the racing helmet any resulting "bump" on the inside of the shield must not exceed 2.5 mm.

Flame Resistance Test
The flame resistance test applies to special application racing helmets only. The test is conducted using a propane flame of approximately 790 degrees centigrade. The flame is applied to the shell, trim, chin strap and face shield for a specified number of seconds, and any resulting fire must self extinguish within a specified time after flame removal. During the whole process the temperature of the interior lining of the helmet must not exceed 70 degrees centigrade.

Three Basic Types of Testing Programs
Certification Test

Official pre-market evaluation for admission to the Foundation's Certification Programs. The manufacturer submits five or six helmet samples, depending on the helmet type and Snell Standard, to the Foundation for testing. Snell technicians at Snell laboratories subject these samples to the most rigorous testing permitted by the Standard. Any failure on any sample is a cause for rejection.
Random Sample Test (RST)

Required testing and evaluation for all certified helmets. The Foundation acquires helmet samples directly from retail or distribution sources from stocks of helmets that are meant to be sold to the general public. The number of samples we will buy is based on the number of helmets the manufacturer has produced. Snell technicians in Snell laboratories inspect and test each sample to check that the Snell Certified helmets used by the public continue to meet the Foundation's high Standards. If it is found that these RST helmets fail to meet the testing criteria, three more samples are obtained and testing to confirm the findings of the first tests. If any of these three follow up tests result in failure, The Foundation first demands that the manufacturer discontinue production of these helmets as Snell certified products. The Foundation will then continue to investigate the matter and determine a suitable course of action. These actions can range from requiring the manufacturer fix the problem and recertify the helmet to a complete decertification of the manufacturers certified product line. In some cases Snell will require that all Snell decals distributed to that manufacturer be returned to Snell. This basically amounts to a full scale recall. Gratefully, this rarely occurs because of the practices taken during the certification and Random Sample

Testing.
More on RST
Prototype Test

Unofficial evaluation. Manufacturers may submit one or more helmet samples and request specific tests and test configurations. The Foundation will not consider prototype test data in evaluation for Certification. However, manufacturers may find prototype testing useful in product development.

The Foundation has published "The Implications of M2000 Testing Policy". This document clarifies the why and what action we take when a helmet fails in the random testing program. The file is in Adobe TM pdf format, and about 190 KB.

The Snell Memorial Foundation has been actively conducting and supporting research to understand the nature and severity of head and brain injury and to increase head impact protection in such activities as bicycling, motorcycling, racing and other non-motorized recreational activities. Basic studies of injury mechanism and protection, as well as field research related to injury severity and causation have been undertaken.

Research support is world-wide, extending from bicyclist injuries in China, to basic modeling and design of an improved anthropomorphic dummy head and neck conducted in the Netherlands, and Germany. Other studies by United States universities, medical and injury prevention centers, and private research organizations have involved basic research in biomechanics and head injury epidemiology, 3-D child head anthropometry, helmet fit research, and seat belt restraining design effects on the body.

In progress are long term studies of the sequelae of head injury in young bicyclists, evaluation of helmet materials, and basic head and brain biomechanics and injury mechanisms. In-house studies are also part of this over all program. The following is a list of recent research projects completed or in progress.

Title: DEVELOPMENT OF A 3-D DATABASE OF HEAD AND FACIAL ANTHROPOMETRY FOR CHILDREN AND YOUTH

Principal Investigator: Bruce Bradtmiller, Ph.D.
Organization: Anthropology Research Project, Inc. Yellow Spring, Ohio
Date: July 1992 - February 1995

Title: HEAD IMPACT ATTENUATION CHARACTERISTICS OF HUMAN SURROGATES

Principal Investigator: Anthony Sances, Jr, Ph.D.
Organization: Medical College of Wisconsin, Milwaukee, Wisconsin
Date: January 1993 - April 1995

Title: OMNI-DIRECTIONAL NECK DEVELOPMENT

Principal Investigator: Jac Wismans, Ph.D.
Organization: TNO Road-Vehicles Research Institute, The Netherlands
Date: April 1993 - October 1995

Title: INJURY TO BICYCLISTS AND MOTOR SCOOTER RIDERS IN WUHAN. THE PEOPLE'S REPUBLIC OF CHINA

Principal Investigator: Prof. Susan Baker
Organization: Johns Hopkins University, Baltimore, Maryland
Date: October 1993 - September 1994

Tile: HEAD INJURIES IN BICYCLING AND INFORMAL RECREATION

Principal Investigator: Prof. Susan Baker
Organization: Johns Hopkins University, Baltimore, Maryland
Date: April 1993 -July 1994

Title: DEVELOPMENT OF A FIT MODEL AND ANTHROPOMORPHIC FIT TEST PROCEDURES

Principal Investigator: Bruce Bradtmiller, Ph.D.
Organization: Anthropology Research Project, Inc. Yellow Spring, Ohio
Date: May 1994 - December 1995

Title: A STUDY OF LOAD LIMITING LOOPS AND ASYMMETRICAL LAP BELT LOADING AND THEIR EFFECT ON AUTOMOBILE OCCUPANTS

Principal Investigator: William H. Muzzy, III
Organization: ARCCA, Inc., Richboro, Pennsylvania
Date: August 1994 - March 1996

Title: HELMET MATERIALS EVALUATION (Not Completed 3/3/2000)

Principal Investigator: Rita Boggs, Ph.D.
Organization: American Research and Testing, Inc., Gardena, California
Date: October 1994- October 1996

Title: DETERMINATION OF PHYSICAL DATA OF THE HEAD II. MASS, CENTER OF GRAVITY AND MOMENTS OF INERTIA HUMAN HEAD-NECK ASSEMBLIES

Principal Investigator: Dr. rer. nat. G. Beier
Organization: Institute of Forensic Medicine, University of Munich, Germany
Date: May 1995 - May 1996

Title: THE CIRCUMSTANCES AND SEVERITY OF BICYCLE INJURIES

Principal Investigator: Frederick P. Rivara, M.D., M.P.H., Diane Thompson, M.S., Robert S. Thompson, M.D.
Organization: Harborview Injury Prevention and Research Center, University of Washington, Seattle, Washington
Date: April 1992 - March 1996

Title: SEQUELAE OF HEAD INJURY IN YOUNG BICYCLISTS - PHASE I

Principal Investigator: Prof. Susan Raker
Organization: Johns Hopkins University, Baltimore, Maryland
Date: April 1995 -June 1997

To improve cooperation with other organizations and expand the educational efforts of the Snell Memorial Foundation, the Snell Safety Education Center was established in 1996 as a non-profit and charitable organization dedicated to provide safety educational services and information to the public. The mission of the Center is to encourage the use of safety equipment for injury prevention purposes. The Center offers free information to anyone interested in helmet safety. Lists of currently Snell certified helmets by name and size, copies of various Snell Standards, brochures, video tapes, and other educational materials advocating helmet safety are made available to the general public. The Center welcomes public donations to support our efforts.

Since its founding in 1957, the Snell Memorial Foundation has independently tested manufacturer's helmets. Its first safety standards for protective headgear were issued for auto racing in 1959. Subsequently, other specific helmet standards for motorcycling, equestrian sports, bicycling, rollerblading and skateboarding, snowboarding and skiing, and karting have been issued. These standards address performance, not specific materials or design. Periodically, utilizing specially designed test equipment, the Foundation upgrades its specifications on performance characteristics of helmets to keep pace with advances in materials, helmet technology and design.

So, What's The Difference?

Standards differ in many ways from country to country, and for different applications. There are also notable differences in the enforcement of safety standards. In some countries standards compliance is overseen and controlled by government agencies. In others compliance is left up to the manufacturer, or distributor of the item. The differences in standards can be confusing to helmet buyers. In an effort to help consumers make more informed choices about the headgear they're buying, we've created some pages of standards comparisons for bicycle helmets, motorcycle helmets and skiing helmets.

So why so many different helmets and standards? Well, all activities are not created equal. You may think that activities like bicycling and skateboarding are pretty much the same, wheeled, non-motorized vehicles that are used on paved surfaces. In some ways they are alike but, they also differ in some important aspects. Studies have demonstrated that the the head impacts that cyclists receive are more frequently located on the front third of the helmet down near the lower edge. This is likely a result of the dynamics of how people ride and the design of bicycles. A rider who is about to be involved in an incident is also likely to be using their hands and arms to try to maneuver the bike rather than for the natural act of protecting their head and face.

Skateboarders generally have less maneuvering capability and thus less active control, except for perhaps those who have an expertise in the activity. The environment that these items are used are commonly less controlled, with a larger variety of unknown hazards. Unlike bicyclists, skateboarders and those who rollerblade, rollerskate and the like are more likely to fall backwards making impacts to the back of the head more common. Their arms and hands are usually free to naturally react and cover at least the front and sides of the head helping to diffuse the impact. It becomes more important that a person on a skateboard, rollerblades or skates have a helmet that offers more protection for the back of the head.

The other problem is, how much helmet will you wear. A good motorcycle helmet will generally provide more protection than just about any other helmet, but they are heavier and do not provide as much venting. This is OK for riding a motorcycle because in general you are not exerting as much physical energy as you would be on a non-motorized vehicle.

Choose a helmet that is designed and tested for the activity you are involved in. If you are bothering to wear one, wear one that will give you the most suitable protection, and the best chance to avoid a serious head injury.

Who/What is Snell?
William "Pete" Snell was an amateur auto racer. He died needlessly in a racing event in 1956 when his then state-of- the-art helmet failed utterly to protect him. His friends, including Dr. George Snively, formed the Snell Memorial Foundation to remember Pete Snell and to encourage the development and use of truly protective helmets.
Why wear a helmet?

Auto racing, motorcycling, bicycling, skiing and any activity that incorporates speed, agility and a head, all impose risks of head injury leading to death or permanent disability. Helmets are the single most effective means of preventing these injuries.
Why wear Snell-certified helmets?

The protective capability of a particular helmet is difficult to measure. One can quickly judge a helmet for style and price, and, with only a little effort, for fit and comfort as well. But who knows what that helmet can do when someone's skill, experience and every other precaution have failed, when his helmet's the only thing between his head and a violent collision. The Snell Foundation knows. We destroy thousands of helmets every year to find out. Snell Certification is our assurance that a helmet has measured up to the highest standards for protective performance time and again.
Why Snell certification and not some other assurance?

Snell Standards are the most demanding. They are set to levels of protective performance that only the best, most protective headgear will meet. But Snell Certification is more than high Standards, it is testing. Helmets must first pass Snell Certification testing by Snell technicians in Snell labs to qualify for our programs. Then samples of these helmets acquired directly from retailers and distributors must continue to pass in order to remain in our programs. Snell Certification is your best assurance that your helmet will perform its most important function: save your life when all your judgment, skill and luck have failed to keep you from harm.
How much does Snell cost and who pays?
Snell bills the manufacturer for testing, the acquisition of random samples and for each Snell Certification label that goes into a certified helmet. However, these costs, along with every other production cost, get passed along to you the consumer.

Why Snell-certified helmets cost more?
Snell Certified helmets are available in almost every price range. Other features such as style and comfort are much more important in determining helmet price. However, building protective performance into a helmet does cost money. The costs are in the design and development, the materials and, most of all, in quality control. Snell Certification is your best assurance that the manufacturer has made, and continues to make, this investment in your safety.
What does Snell do with the money?

The Foundation spends the biggest part of its income on the Certification Programs. There are rents and maintenance on it's test facility in California, salaries for the test technicians and other employees, equipment repair and replacement, and all the other expenses associated with any non-profit effort. The rest goes to research projects and the Foundation's extensive educational program.

What are the differences between the SA and M standards?
SA Standard was designed for auto racing while M Standard was for motorcycling and other motorsports. There are three major differences between them:
SA standard requires flammability test while the M standard does not;
SA standard allows narrower visual field than M standard (Some SA helmets may not be street legal);

SA standard has rollbar impact test while M standard does not.
Why does Snell make my racing association upgrade to the newest Snell Standards?
In short, we don't. Snell always makes itself available to explain our standards and programs. We may even offer recommendations on some issues. Each association has the responsibility for the safety of its members or participants, which generally creates a unique set of issues that must be dealt with, and rules to be set accordingly.
How do helmets works?

Your helmet is normally comprised of four elements: rigid outer shell, crushable liner, chin strap and fit or comfort padding. The rigid outer shell, when present, may add load-spreading capacity and prevent objects from penetrating the helmet. The liner, usually made of EPS (expanded polystyrene), or similar types of materials, absorbs the energy of an impact by crushing. The chin strap, when properly buckled and adjusted, along with the fit padding helps the helmet remain in position during a crash.
Why replace helmet every five years?

The five year replacement recommendation is a consensus position from both the helmet manufacturers and the Snell Foundation. Glues, resins and other materials used in helmet production can affect liner materials, and general liner deterioration as a function of hair oils, body fluids and cosmetics, and normal "wear and tear" all contribute to helmet degradation. Additionally, experience indicates there will be a noticeable improvement in the protective characteristic of helmets over a five year period due to advances in materials, design and the standards. Thus, the recommendation for five year helmet replacement is a judgment call stemming from prudent safety philosophy.

Why won't Snell certify some types of helmets like flip up front designs?
Snell does not dismiss out of hand, any helmet design that strays from the conventional. Snell does not point out any design specifications, other than general requirements in our standards. We are however, always concerned with innovations and new designs that may effect the helmet's ability to protect the wearer, or in some cases the helmets potential to cause injury. At present, the Foundation has not had the opportunity to test any of the flip up front type helmets. So far, we can not find any fault with these designs as long as they are used according to the manufacturers instructions. We will also certify any size of helmet as long as it meets the same requirements as any other Snell certified helmet.

How do you test a helmet, do you stand around hitting people on the head?
This question is probably the winner of the most Frequently Asked Questions award, and all I can answer is "Not Anymore". Actually, The testing of helmets is a fairly straightforward process. While most helmet testing is denoted "performance testing" (How well a device or piece of equipment performs under defined conditions that are analogous to real life situations), rather than "materials testing" (The testing of materials that will be used in the construction of an item, to a defined set of conditions in controlled settings), it is really a combination of both. This is because it would be virtually impossible to perform a true performance test on a helmet that would be at all repeatable, and that you could readily ascertain a helmets capabilities in a variety of scenarios. What has been decided is that testing needs to replicate possible stresses the helmet might see in a wide variety of incidents rather than to try to duplicate a real life incident. True to this philosophy a helmet is tested for a variety of criteria: retention strength, stability (how well the helmet will stay on), penetration resistance, chin guard strength (if applicable), face shield integrity (if applicable), and most importantly impact energy management. Most helmet standards also have requirements for coverage and visual clearances. Helmet testing is a destructive process, meaning that all tested helmets are destroyed during the process. All of the requirements of the Snell standards are described in each individual standard.
So, why aren't all helmets certified by Snell?

Some helmet manufacturers do not believe that they need Snell to demonstrate that their product is among the best protective headgear. Others believe that they need only to produce helmets that meet Government or consensus helmet standards, and some try and just can't make the grade. A very few helmet makers are truly inconsiderate of the consequences of making an inferior safety product (they are not usually around very long).

Where's the Snell label located?
There are two forms of the Snell serialized label. The most common is the adhesive label, but there is also a cloth type for the M, SA and RS standards. The adhesive label, or decal is usually affixed on the inside of the helmet. If it is not readily visible, check underneath the flaps of the comfort padding. The cloth type labels a generally sewn onto the chin strap and folded over. If a thorough search fails to turn up a decal then your helmet is not part of the Snell certification program and does not have the confidence of the Foundation.

Research shows most of the cycling fatalities are attributed to head injuries. In a severe accident, your skull may be fractured and your brain may be torn by penetrating objects and bone fragments. Brain injuries can also occur by violent impacts that leave the skull undamaged. To protect yourself against those head injuries, Snell Memorial Foundation urges you to wear a helmet when you are riding.

Finding a good helmet is as easy as remembering the 4 S's: Size, Strap, Straight and Snell.

Size: Try on several different helmets before you purchase one. The best way to gauge comfort level and fit is through comparison. The helmet should fit comfortably all the way around your head. Additional pads can be used to make it snug.
Strap: Pay attention to the chin strap. Make sure that the chin strap fits around your ear and under your chin snugly and comfortably. The helmet should not shift on your head.

Straight: Know how a helmet should fit. A helmet is meant to be worn low on the forehead, just above your eyebrows. Look into a mirror or have a friend/parent help you determine the proper fit.
Sticker: Look for Snell certification. Snell Standards are the most stringent in the world, exceeding those set by the Consumer Products Safety Commission (CPSC), American Society of Testing Materials (ASTM) and the American National Standards Institute (ANSI). Need to know which helmet is Snell certified? Browse through our helmet certification lists.

Technicians at two state-of-the-art laboratories, located in the United States and the United Kingdom, test helmets on two levels. First, helmet samples from manufacturers are tested to see if they meet Snell certification testing requirements. Then, once a helmet passes and receives the Snell certification sticker, it is subjected to random sample testing. These dual-testing procedures are designed to see that the product a consumer buys off the shelf is as protective as the one submitted for initial testing.
Once you've selected a helmet, remember that it must be worn correctly every time you ride a bike. A helmet should be replaced immediately if damaged, and at least every five years based on wear and tear.