A Buyer's Guide
to Bicycle Helmets
The Two Minute Summary
- You always need a helmet wherever you ride. You can expect to crash in your next 4,500 miles of riding, or maybe much sooner than that!
- Even a low-speed fall on a bicycle trail can scramble your brains.
- Laws in 22 states and at least 201 localities require helmets, although few cover adults.
- Make sure your helmet fits to get all the protection you are paying for. A good fit means level on your head, touching all around, comfortably snug but not tight. The helmet should not move more than about an inch in any direction, and must not pull off no matter how hard you try.
- Rear stabilizers do not substitute for careful strap adjustment.
- Pick white or a bright color for visibility.
- Common sense tells you to avoid a helmet with snag points sticking out, a squared-off shell, inadequate vents, excessive vents, an extreme "aero" shape, dark colors, thin straps, complicated adjustments or a rigid visor that could snag or shatter in a fall.
- Consumer Reports and Virginia Tech have some model recommendations.
If you have six minutes, please read on!
Six Minutes More
Your brain is probably worth reading this!
The average careful bike rider may still crash about every 4,500 miles. Head injuries cause 75% of our nearly 700 annual bicycle deaths. Medical research shows that bike helmets reduce or prevent most of cyclists' head injuries. And helmets may be required by law in your area.
Need One? Yes!!
A helmet reduces the peak energy of a sharp impact. This requires a layer of stiff foam to cushion the blow. Most bicycle helmets use crushable expanded polystyrene (EPS), the picnic cooler foam. It works well, but when crushed it does not recover. Expanded polypropylene (EPP) foam does recover, but is much less common. Collapsible plastic liner materials recently appeared in Bontrager helmets and are claimed to reduce concussion-level energy. A MIPS slip-plane layer is also claimed to do that. The spongy foam pads inside a helmet are for comfort and fit, not for impact protection.
How Does a Helmet Work?
The helmet must stay on your head even when you hit more than once--usually a car first, and then the road, or perhaps several trees on a mountainside. So it needs a strong strap and buckle. The helmet should sit level on your head and cover as much as possible. Above all, with the strap fastened you should not be able to get the helmet off your head by any combination of pulling or twisting. If it comes off or slips enough to leave large areas of your head unprotected, adjust the straps again or try another helmet. Keep the strap comfortably snug when riding. The straps hold your helmet on, not the rear stabilizer.
Most bike helmets are made of EPS foam with a thin plastic shell. The shell helps the helmet skid easily on rough pavement to avoid jerking your neck. The shell also holds the foam together after the first impact. Many excellent helmets are made by molding foam in the shell rather than adding the shell later.
What Type do I Need?
Beware of gimmicks. You want a smoothly rounded outer shell, with no sharp ribs or snag points. Excessive vents mean less foam contacting your head, and that could concentrate force on one point. "Aero" helmets are not noticeably faster, and in a crash the "tail" could snag or knock the helmet aside. Skinny straps are less comfortable. Dark helmets are hard for motorists to see. Rigid visors can snag or shatter in a fall. Helmet standards do not address these problems--it's up to you!
A sticker inside the helmet tells what standard it meets. Helmets made for the U.S. must meet the US Consumer Product Safety Commission standard, so look for a CPSC sticker. ASTM's F1447 standard is similar. Snell's B-95 standard is tougher but seldom used.
Fit is not certified by any standard, so test that on your own head. Visors are not tested for shattering or snagging in a fall, so you are on your own there.
Coolness, ventilation, fit and sweat control are the most critical comfort needs. Air flow over the head determines coolness, and larger front vents provide better air flow. Most current helmets have adequate cooling for most riders. Sweat control can require a brow pad or separate sweatband. A snug fit with no pressure points ensures comfort and correct position on the head when you crash. Weight is not an issue with today's bicycle helmets.
Some head shapes require more fiddling with fitting pads and straps. Extra small heads may need thick fitting pads. Extra large heads require an XXL helmet. Ponytail ports can improve fit for those with long hair. Bald riders may want to avoid helmets with big top vents to prevent funny tan lines.
We have put together ratings from Consumer Reports and the Virginia Tech STAR concussion ratings on our page with both.
How to Buy
We have a review up on helmets for the current season. It has no impact ratings, but our limited testing has shown that most helmets have about the same impact protection regardless of price.
When you pick up a helmet, look first for a CPSC sticker inside and a smooth, well-rounded shell with a bright color outside. Put it on, adjust the pads and straps or the one-size-fits-all head ring, and then try hard to tear it off. Look for vents and sweat control. Helmets sell in bike shops from $30 up, or in discount stores for less. A good shop helps with fitting, and fit is important for safety. The $10 discount helmet can be equally protective if you take the time to fit it carefully, and for another $10 you get easier fitting. Helmets are cheap now, so don't wait for a sale price. Many of us bought our helmets after a crash. You can be smarter than that.
Check out our pamphlet on child helmets.
Replace any helmet if you crash. Impact crushes some of the foam, although the damage may not be visible. Helmets work so well that you need to examine them for marks or dents to know if you hit. Most manufacturers recommend replacement after five years, but research has shown that unless crashed they perform well much longer than that. We think that depends on usage, and many helmets given reasonable care are good for longer than that. But if your helmet was made before 1990, it's time to replace it. Replace the buckle if it cracks or a piece breaks off. No one requires you to replace your helmet, so give it some individual thought.
When Must I Replace a Helmet?
The ASTM standard for biking includes inline skating. But extreme, trick, aggressive skating and skateboard helmets should meet ASTM F1492, tested with multiple hits and lesser impact severity. Those helmets may not handle bicycling impacts. Do not use a skate helmet for bicycling unless it has a CPSC sticker inside! The best skate helmets are dual-certified to F1492 and the CPSC bicycle helmet standard.
Bike Helmets for Skating?
Warning: Children must remove helmets before climbing on playground
equipment or trees, where a helmet can snag and choke them. Here is
more information on that problem.
Warning! No Helmets on Playgrounds!
The Bicycle Helmet Safety Institute
BHSI is a helmet advocacy program whose volunteers provide helmet information and work on the ASTM helmet standards committee. We are funded by consumer donations of about $11,000 a year. We do not accept funds from manufacturers or anyone involved in helmet sales. Here is our contact info and our program for this year.
This pamphlet was produced with donations from those who read it earlier. We welcome your tax-deductible donation to make it available to the next rider or parent who will need it. Checks can be made payable to BHSI or you can donate online. Thanks!
Copyright 2019 by the Bicycle Helmet Safety Institute
Illustrations by Nancy Olds