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.
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 is introducing 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. Designed only to the European EN 1078 standard, so not available in the US.
Overade has announced a folding helmet with a complex folding mechanism. It is promised for the spring of 2013, and the pre-production price is $97 including shipping in France. We don't know what standards it has been designed to.
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.
This page was last revised on: January 16, 2013.