Bicycle Helmet Safety Institute

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One-size-fits-all Bicycle Helmets

Summary: Helmets that fit using an adjustable ring around the head work well with some head shapes but not with others.

Back in the 1970's, the Bailen bicycle helmet was made with an inner ring that could be adjusted to fit a wide range of head sizes. It was patterned after the hard hats worn in construction sites and other headgear that used the adjustable band. The Bailen ring conformed to the shape of the head without fiddling with pads of varying thicknesses, could be easily readjusted for different riders, grew with your child and provided a space for air circulation between the inner surface of the helmet and the head. It did not fit all heads equally well, however.

Those same advantages led other manufacturers to produce bike helmets with ring fit systems, also known as one-size-fits-all, universal fit and by various other marketing terms. Most of those helmets have been produced in Europe, and you can find descriptions of them in our reviews of helmets by Cratoni, Hamax, and others. Those companies have a very small market share in the US, but sell more helmets in Europe.

For the 2002 season, both Bell and Giro introduced one-size-fits-all helmets with ring fit systems in the US and Canadian markets. Nearly all major manufacturers have them now, with a variety of clasps and fittings to snug the ring up to your head size. In 2009 Bell introduced another step, their True Fit system that simplifies fitting further. Unfortunately, True Fit has not been aggressively marketed, so only a few models in big box stores have it.

In addition to the consumer advantages cited above, dealers are interested in adjustable size helmets because the system means:

We have been looking for consumer feedback on the ring fit systems.

Negative comments indicate that some riders find that some of the onesize helmets require the ring so tight for real stability that they feel binding after a few minutes, and loosening the band gives a sloppy fit. In addition, the headband used will also interfere with anyone using a separate sweatband or earband. Some riders use both, shifting from the sweatband to the earband as temperatures drop in the fall. If the bands are of similar thickness the standard fit pads can be adjusted once to work well with both without changes. Fitting the bands under a ring fit system may be difficult because they are not likely to correspond to the orientation of the ring, and may result in the helmet shifting in use or in unequal pressure on parts of the head. One rider with a 63cm head indicated that there is a gap between the largest one-size-fits-all size and the largest of the oversize helmets.

Positive comments have included the same praises as the old Bailens: quick fitting and the ability to accommodate some unusual head shapes that are difficult to fit with a conventional helmet. Those with rounder heads who have been forced to use thick pads at the back and front of pad-fit helmets may find that the ring fit is faster and easier. The ring fit's easy adjustability allows for wearing a sweatband or cap underneath the helmet--you are unlikely to change fitting foam pads just to ride home without a cap. For some head shapes the ring positions itself more tightly on the back of the head. Fewer pads can improve air circulation. And the ring does not break down from sweat. When foam pads are sweaty they can get slippier and seem thinner, and in the long term the foam always breaks down. If you require thick pads the fit deteriorates, while the ring fit system provides a close fit using only thin pads, reducing pad variations over time.

In short, there are plusses and minuses for helmets with ring fit systems, and your mileage may vary. If you have been using one, or have tried one on in a store and have observations about how it works for you, please send us an email with your thoughts. We are indebted to those who did for the comments above.

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