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Bike helmets in very cold weather


Summary: If you are going to be using a bike helmet in very cold weather you might wonder if the cold will affect helmet performance. Helmets are tested for that.


The CPSC and ASTM standard in the US require that a helmet pass lab tests after conditioning in cold at temperatures in the range of -13 to -17 degrees C (F 9 to -1 degrees). Most other standards, including cold places like Canada, have a similar requirement. These temperatures should cover most bicycle riding. There are at least two other standards with lower temperature tests: the Swedish standard (now supplanted by the CEN European standard) had a requirement for testing at -20 C/ -4 F, the same temperature specified in both the current Snell Memorial Foundation B-90 standard and Snell B-95 standard. You can find lists of Snell-certified helmets on the Snell website. If you regularly ride at those lower temperatures it might be worth looking for a Snell-certified helmet. Here are the requirements of the various standards included in our Standards Comparison: If for some reason you are using a bike helmet at lower temperatures, what should you expect? The EPS foam used in most bike helmets does stiffen somewhat at lower temperatures, but the impact performance has been tested at the temperatures listed above, so that is not serious. All of the plastic parts of a bike helmet could be expected to become more brittle while they are cold. This would include exterior shells, internal reinforcing and buckles. Buckles are reportedly tested at lower temperatures without any significant degradation. Internal reinforcing and exterior shells help to keep your helmet together for a second impact (typically when you hit the pavement after the first hit on the car) and their strength could be affected, although unless the helmet is stored outdoors it could take some time for cold to reach the internal elements. But once again, the buckle, shell and reinforcing have been tested at low temperatures to certify that they will meet the minimum requirements of the standard. And the conditioning before testing is long enough for the entire helmet to reach that lower temperature.

There is no permanent damage from exposing a helmet to cold weather--once the helmet warms up any effects of cold storage disappear.

Visors are worth a separate comment. Visors are not tested for shattering under the ASTM or CPSC protocols, or for that matter by other countries' standards. They might shatter in colder weather. In fact, they might shatter in cool or warm or hot weather too, and the helmet would still pass both of our US standards. That is part of the reason we don't advise using a visor unless you really need one for sun or rain problems. We have a page up with more on visors.

Cold weather comfort is usually easy to achieve with a bike helmet, even with temperatures well below freezing. See our page on winter bicycle helmets for discussion of that.

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