Folding bicycle helmets are easier to carry off the bike and could be useful for shared bicycle programs. There are few of them on the market, and they don't meet US standards.
Folding a helmet can make it easier to carry, so users of folding bicycles have always found them appealing. Users of shared bicycle programs would like a collapsible helmet they could tuck into a purse or briefcase and pull out when they use one of the shared bikes.
Although a helmet may fold, it still requires the same volume of impact foam. To manage the energy of an impact, the foam must be thick enough to give the head room to stop in a controlled deceleration. So the helmet materials can fold, but the volume of material will be the same. In addition, the helmet has to maintain its structural integrity in an impact, requiring some engineering skill to design and probably more expensive materials to construct.
The first folding helmet we know of that met the US CPSC standard was the Motorika Snapit, introduced in 1997. It was a clamshell design with one half folding inside the other. We did not like the ridge left from back to front when it was unfolded in use, and the 16 oz. (454 grams) weight discouraged some buyers. It disappeared from the market soon after the turn of the century.
In 2014 we were notified by Closca that their folder now has been certified to the CPSC standard, and is for sale in the US. The design consists of three concentric rings that fold down inside each other. Unfortunately it has a cloth cover rather than plastic. It retails on their web site for 62 euros.
There is at least one folding helmet on the European market now, and two more have been announced in France and Italy. The current design by Biologic has two sides that fold into the center. It does not meet the CPSC standard, so it is not available in the US market, but it meets the CEN standard and is sold in Europe.
Carrera introduced for 2013 an "Accordion" model made of strips joined by an elastic frame that opens to provide vents between the strips and folds into a solid piece to reduce the width for storage. This Youtube clip from the 2012 Eurobike show shows it in action, and there is more on it here. It is now on the Carrera web page. In late 2013 they reported to the press that the helmet meets the US CPSC standard, and they are looking for a US distributor. In 2015 Carrerra introduced a similar if not identical design as the Crit model for 2016 that they say folds to save 20% of storage space. There is a waterproof version, presumably for cold rain and ebike users who don't sweat. There is a reflective version as well. The press release says it is certified to both the CEN and CPSC standards. Online prices vary widely.
Closca of Spain produced its first folder model in 2013. It was CEN-certified at that time, and they hage sicnes obtained certification to the US CPSC standard. It collapses from the top into a compact ring for carrying.
Overade has a folding hardshell helmet with a complex folding mechanism. It meets the CEN helmet standard, and the Small/Medium version meets the US CPSC standard as well. It is available on the European market at about $135.
Morpher began raising funds on November 1, 2013 through Indiegogo to launch a new line of folding helmets that fold flat. They will be testing first to the European CE standard, but intend to produce a CPSC model later. A true flat-folding helmet would be very useful for briefcase storage.
Put A LID on It is developing a folding helmet designed for shared bicycle programs. In mid-2015 they are crowdfunding.
Folded or not, a helmet is another item for a pedestrian to carry unless planning in advance to use a shared rental bicycle. That may not be a problem for backpack users, but those with purses or briefcases have to carry the helmet elsewhere. We are glad to see some models emerging that meet the US standard.
This page was updated or partially revised on: September 22, 2015.