Bicycle Helmet Safety Institute

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Hard Shell Helmets

Summary: The hard shell helmet is still available if you prefer it. In an impact the energy management will not be much different from the thin shell models, since all are designed to the same CPSC standard. But for sliding resistance or in that very rare impact with a pointed object the hard shell would perhaps be better. If you prefer it and don't mind the weight, there are still some choices out there, but very few road models.

In the early days of bike helmets, manufacturers started with a hard outer shell and added the foam liner inside to manage energy. Then Bell discovered in the early 1980's that the hard shell was not really necessary for thick child helmets. Giro began marketing no-shell helmets for adults in 1986. Soon people noticed that Giro's no-shell design broke up in a crash. So manufacturers added internal reinforcing, then added a thin plastic shell on the outside to solve that problem. The thin plastic also made the helmet slide better on pavement in a crash to avoid jerking the rider's neck. The result of eliminating the hard shell was a lighter helmet that could use almost all of its thickness for energy managing foam. Since consumers reject thicker helmets that make their heads look like mushrooms, this was a net gain. Molding the foam in the thin shell as a single process can fill every part of the shell with foam, potentially increasing the strength and impact management capabilities of the helmet. (In fact, designers generally use that technique to open up bigger vents, not to increase impact management.)

Dr. Voigt Hodgson did some research at our request at Wayne State University on sliding resistance of helmets. He discovered that the old hard shells had the least sliding resistance, followed closely by the thin shell designs that dominate bike helmets today. He also confirmed that if a helmet does not slide well it can increase both the strain on the neck and the g force seen by the rider's brain in a crash.

One problem with all hard shell helmets on the market up until 2001 was that the manufacturers were not been able to mold the liner in the shell. That means that there are small voids between shell and liner, and the helmet is a little less protective than it might be for a given helmet size.

One of the persistent questions we receive by email is "where can I find a hard shell helmet to replace my old one?" There are a few hard shell bike helmets, and you can find them on our page on helmets for the current season. Some have chinbars, and a few have removable chinbars.

Another type of hard shell is the full face helmet made for downhill racing. These are vented, but still hot and heavy for regular street use. The third hard shell is the BMX helmet, really a lightweight motorcycle helmet. You can find all of those styles covered in our latest article on helmets for the current year.

In addition, there are numerous skate-style hard shell helmets out there, but they may not be what you want. Most are made in the classic skate style with a very round smooth shape but with tiny vents. If cooling is not a problem for you, these are good helmets, provided they meet the CPSC bicycle helmet standard. Note that skate helmets not for bike use can legally be sold without meeting any standard at all! Almost all of the "skate" helmets now in big box stores are in fact bicycle helmets in the skate style, so you have lots of choices there. We have a page up on that and another on helmets that are dual-certified to both bike and skate standards, a definite plus.