Summary: Rental helmets should be easy to fit, show damage clearly after an impact and be easy to clean for the next customer. We have not found any bicycle helmets on the market with those characteristics. Seattle's Pronto bike share system is providing helmets to their users for $2 each.
The first requirement for a rental helmet is that it be easily and quickly fitted. Rentals are usually for a day or less, and the wearer will not put much time or effort into fitting. They will settle for a sloppy fit because the use is short term and they do not expect to crash anyway. Rental shop staff may be too rushed to fit a finicky helmet well. The only manufacturer we know of who has responded to this requirement is Bell, with their 2009 introduction of the True Fit system. We normally would not recommend a single manufacturer's product, but True Fit helmets fit more quickly than others we have tried because they require adjustment of only one strap. We are sure that other manufacturers will be scrambling to compete, so choices should expand soon.
Bike helmets for rental services should show damage readily if the user has hit their head during the ride. The user will almost never report that, and may actually be unaware that they hit their head hard, since the helmet cushions the blow. The best helmets to show damage every time would have no outer shell, or a removable cloth cover. But those don't perform as well as helmets with a normal thin or hard plastic shell. As far as we know, no manufacturer has addressed this problem. There are physical indicators of strong impacts available, but made only for hard shell helmets. In 2010 we saw reports of a process to embed odor-producing chemicals in foam, to produce a smell if the foam is damaged. As far as we know, no indicator of any kind has been included in a bicycle helmet available on the market.
Rental helmets must be easily sanitized. Rentals are almost sure to have hair oils and sweat when returned. They may also have hair preparations, Rogaine, sun screen, head lice or nits and an entire bacterial colony inside or outside. Cleaning with the normal mild soap and water will remove some of that, but not all. Nits are hard to remove, as noted on our head lice page, and can be best taken care of by leaving the helmet unused in a plastic bag for two weeks. Most rental shops can not afford to do that. As far as we know, no manufacturer has addressed this problem either, although helmets with a full inner plastic shell would make it easier than those with the foam inside uncovered. We list some of those in our Helmets for the Current Season article, found with a search for "inner."
If the helmet is being used in a controlled setting such as a school class, it may be possible to use a head covering that prevents contact with the wearer's head. We suggest some possibilities on our head lice page. For unsupervised rentals, that will not work, since the user is likely to remove the head covering to get more ventilation, or remove the helmet and be careless about repositioning the cover, and the rental shop has no way of knowing that. One of the spray delousers we mention might be the best solution, followed by soap and water. There are more sophisticated methods of sanitizing with ethylene gas or ozone chambers, probably out of reach for the normal rental shop. Whatever method a shop uses, we recommend contacting the helmet manufacturer to ask if the product is compatible with their materials.
Methicillin resistant staph infection (MRSI's) have become serious problem in medicine including emergency rooms and in pediatric medicine. Once primarily related to hospitals, they now are seen within the public spread by skin-to-skin contact including objects such as towels and lockers. Because MRSIs can be transmitted by skin contact and into hair follicles and into or from small skin wounds, it is a red flag issue related to sharing of helmets. We do not know the degree of this risk. A reasonable reference starts with the CDC's web materials. Or you can quickly find insights by a google search of methicillin resistant staph infection.
Shared bike programs have been looking for ways to distribute helmets to riders who want to use one of their bikes but don't have a helmet along. While Melbourne had the first helmet vending machines on the street for a shared bike program, a team of MIT students developed a much more ambitious design. It is compact to fit in the limited space available for most shared bike stations. The first ones are being installed in Boston in 2013. Here is a good description. They show promise, including rental or purchase options. The cited price for purchase seems high at about $20, but rental at $2 would be reasonable.
The ideal is not available
To our knowledge no helmet manufacturer makes an easily-fitted helmet specifically designed for rental shops with quick, easy, repeatable, routine delousing and cleaning in mind and a damage indicator. We think there would be a market for such a helmet if anyone produced one.
Seattle's Pronto program providing helmets
Seattle's Pronto bike share system is providing helmets to their users for $2 each. The helmets are sanitized between uses. You can find out more about their system on the Pronto page.
This page was updated or partially revised on: March 19, 2015.