Bicycle Helmet Safety Institute

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Our official comment on Hövding's petition
for exemption from the CPSC standard

Summary: the airbag manufacturer Hövding petitioned the Consumer Product Safety Commission for an exemption from the U.S. bicycle helmet standard. Our comments emphasize that the airbag does not provide impact protection equal to a conventional CPSC-compliant helmet, even if tested pre-inflated. We also note many other problems with the reactive design.

Comment by the Bicycle Helmet Safety Institute on the
Hövding Petition for exemption from CPSC 16 CFR 1203 bicycle helmet standard
Docket number CPSC-2018-0003

April 29, 2018


Hövding is asking CPSC to permit its product to be sold in the U.S. market even though the headgear does not provide protection at the level of the current CPSC standard. We regard the issue of differing technology as distinctly secondary.

Although CPSC might choose to make modifications in its standard to accommodate new designs, the level of protection for the user must be maintained. The Hövding reportedly fails to perform at the level of the European bicycle helmet standard, generally considered easier to meet than the CPSC standard. The Swedish lab test protocol Hövding proposes to replace CPSC 16 CFR 1203 actually uses very similar lab tests, but at much lower levels of impact. This indicates that the protocol does not call out headgear with protection that is equal to a CPSC-compliant helmet.

Because of its reactive design, the Hövding may not be in position to manage the energy of an impact when it occurs. An airbag that cannot anticipate common obstacles and injury threats that do not involve pre-programmed fall movements is unable to provide comprehensive protection equivalent to an always-there conventional helmet.

We agree with the research paper attached to the Hövding petition: "However, before this technology becomes widely available, airbag helmets need more reliable impact triggering technologies and should be evaluated in more realistic bicycle accident simulations."

We recommend that CPSC deny this petition.


We comment below on issues regarding lab testing, airbag design problems, Hövding test reports and other considerations.


An inflated Hövding can be tested for impact management with the CPSC test rig with minor modifications to the headform and anvils that would not compromise the assessment of protection.

Anvils The test of the Hövding described in the Folksam article attached to the petition had to use modified anvils: "When testing the Hövding 2.0, similar principles were applied as in the standard EN 1078, 5.1 Shock Absorption. However, in both the shock absorption test and in the three oblique tests, an anvil with larger dimensions was used (Fig. 7). The reason was that if Hövding 2.0 had been tested against the anvil used for a conventional helmet, there was a risk it could get in contact with the sharp edges of the anvil." At a minimum, the surface dimensions of the flat anvil called out in 16 CFR 1203 would have to be increased. The modification is minor, but this raises a question about how the airbag would hold up if it encountered a sharp object during a crash such as the teeth on a bicycle chainring, or something in the environment such as the corner of a car door. Conventional helmets can handle both.

Test headforms called out in 16 CFR 1203 are constant-mass ISO-DIS 6220-1983 and differ from the ones called out by the test lab protocol included with the petition, which uses EN 960 variable mass headforms. Neither has a neck, a question raised in the Folksam article attached to the Hövding petition:
"Since a neck is expected to provide the necessary support for the Hövding in the rotation tests, comparative tests were conducted both with and without a neck on the test head. A Hövding 2.0 with a neck only had a slightly higher rotational velocity than one without; Figure A and Table A. The test results for the Hövding 2.0 without a neck are reported in the study. The reason for this is that for a conventional helmet it has a significant effect on the test results if it is tested with a neck, see Figure A. The accident scenario and also the test scenario are very short (10-20 ms) for a conventional helmet and previous studies have shown that the neck is only rotated 10 degrees during this procedure. It is therefore probably a completely realistic scenario for the conventional helmets not to use a neck. Several researchers have highlighted that this should be investigated further (Fahlsted, 2015) and that it is particularly important to investigate the impact the neck has on longer impact durations, such as for the Hövding 2.0 head protector."

The lab test protocol attached to the petition has drops on both the flat and curbstone anvils, but at much lower levels than a CPSC test, so it does not assure equivalent levels of protection. The lab test protocol tests the helmet in a drop of only 3.8 m/s on the curbstone anvil (about 0.7 meters), well below the 4.8 m/s (1.2 meters) of the CPSC standard. On the flat anvil it uses 4.5 to 5.8 m/s (1.0 to 1.7 meters), again well below the 6.2 m/s (2 meters) of the CPSC standard. We do not know why Hövding has not tested on a CPSC rig at CPSC drop heights and reported the results to establish their level of protection. The one reported test on a European test rig failed the Hövding. [3] We conclude that Hövding is seeking an exemption from required protection levels, rather than just a different test protocol.

Positional Stability
We reject the petition's assertion that testing for positional stability would not be necessary. Since the inflatable device would be worn as a collar and the lab equipment for the 16 CFR 1203 standard and other bicycle helmet standards has no neck, new lab equipment adding a neck structure would be required to assess the positional stability and retention system strength. For positional stability, the test would have to assess the ability of the collar to remain on the wearer under various conditions prior to inflation, and to keep the inflated airbag on the head during a variety of crash sequences. Neck strain would have to be assessed to be sure the device would not increase neck injuries during crashes or in a snagging scenario, both before and after inflation. The test protocol included with the petition uses a shoulder dummy rather than a test neck, although a realistic test would require adding a neck accessory.

Wet testing
The Hövding comes with instructions and graphic warnings on the exterior that tell the user not to immerse it in water, so the normal immersion test used in 16 CFR 1203 and all ASTM helmet standards cannot be used. This section of the standard ensures that the helmet will function in spite of riding in rain. The lab test protocol attached to the petition suggests use of one of two spray or dribble water tests, but CPSC and ASTM have rejected spray tests as inconclusive. Eliminating the immersion test raises questions about the inflatable device's ability to continue to function in normal cycling environments. CPSC would have to waive that requirement in 16 CFR 1203 to accommodate the Hövding design.

The only evaluation of fit in 16 CFR 1203 is the positional stability test. That is a crude approximation for evaluating fit, requiring only that the helmet not come off the headform. The ASTM F1447 version of the positional stability test at least has a standard for how far the helmet can move during the test and still pass. Neither standard would be appropriate for evaluating the fit of an inflatable helmet. The hook used under the edge of a helmet might deflate the airbag, and in any event it would not provide a realistic test of whether or not the collar would stay on a neck before and after inflation.

The Introduction to the lab test protocol included with the petition states that: "To achieve the performance of which it is capable, and to ensure stability on the head, it is of great importance that the head protector is of a shape that fits the user's head and neck." But there is no provision in the lab test protocol for assessing fit.

There would be no impact attenuation if the device failed to inflate. Assessing impact management if the device were to be inflated would require detailed specifications for the pressure in the airbag at the time of initial deployment and in the seconds that follow prior to a second impact. The worst bicycle crashes typically involve a collision with a motor vehicle followed by a second impact with pavement, stanchions, curbs or other obstacles. Conventional helmets work well in this scenario provided the fit system is well adjusted. A Stanford News article on the research paper attached to the petition [1] indicated that the inflation of the airbag was critical to performance, and indicated that the deployment device in the airbag headgear tested was inadequate to ensure optimal performance. Inadequate inflation could cause the airbag to bottom out, providing much less protection than a normal helmet. Loss of pressure in an airbag following the first impact might render it ineffective for a second impact, particularly with a curb or stanchion. Developing protocols to assess the performance of an inflatable in a two-impact situation would require extensive modifications to current data acquisition setups for 16 CFR 1203. Speed of deployment is another parameter that would have to be assessed.

Published Hövding test reports

The Hövding has been reported to fail the European bicycle helmet test when inflacted and impacted on the EN 1078 curbstone anvil. [3] The 16 CFR 1203 standard uses an additional hemispheric anvil and generally more severe impacts, raising questions about the Hövding's ability to protect when impacting anything but a flat anvil. Testing done at Stanford [2] and in other labs has been only on flat anvils.

We note that the research for the journal article attached to the petition did not test the airbag helmet against anything but a flat anvil, ignoring the hazards of the real-world environment. Testing of the Hövding has been reported in at least two other publications. The most relevant was the French consumer magazine Que Choisir and its Swedish affiliate Rad&Ron. [3] They found that the Hövding did not meet the European EN 1078 bicycle helmet standard. Their comment on Hövding's accreditation: "Accreditation, however, consists only in letting the Swedish laboratory SP test the helmet according to criteria considered by SP. No third party in the form of authority or other lab has reviewed the test method." (We note that the SP test protocol has been accepted by the Swedish Board for Accreditation and Conformity Assessment, but only for compliance with the requirements for the CE mark, not the EN 1078 helmet standard.)

The magazine further commented: "For example, an inflated Hövding did not absorb enough energy in the standardized test where the helmet was released against a 130 mm wide steel rod. The result was significantly worse than for regular bicycle helmets. The company Hövding explains the results that instead of testing their helmet against wider metal objects than the 130 mm standard, the results will be much better. But in traffic there are many scenarios where just head protection against narrow, hard objects is crucial. It's far from always the biker's head hits the wide asphalt, the helmet will also protect against metal posts, sidewalks and the like." That comment speaks to the principle that no matter what the design, the headgear must protect against real-world hazards. Those results indicate that Hövding would want CPSC to remove the hemispheric and curbstone anvils from 16 CFR 1203. It further suggests that the petition for exemption from the standard's provisions is not simply because the design is radically different, but is a request for exemption from the protection level required in the US standard.

The second article published about testing a Hövding is from the Swedish insurance company Folksam and is attached to the petition. It states that the helmets tested had all passed the EN 1078 standard. Folksam's testing did not attempt to verify that each model met all the requirements of that standard. But the Hövding had not passed EN 1078, and therefore its inclusion in the article is misleading. It had not passed testing at full height on the kerbstone anvil. Its retention system had not been tested for strength or stability. Folksam tested only on flat anvils, again exempting the Hövding from meeting tests for real-world hazards.

Hövding suggests the use of a Swedish lab test protocol, attached to their petition. It has some provisions that are highly subjective judgments of the lab technician, such as this one: "The product shall be examined to identify surfaces on or adjacent to the inflatable chamber, which contact the skin, where an excess amount of heat could be transmitted." The protocol also allows manufacturers to pick alternative test procedures if their helmet fails a test: "If head impact occurs before the head protector has reached inflated status, the manufacturer can choose to have the shock absorption test performed at the actual pressure at head impact." No US helmet standard has ever given a manufacturer the choice of alternative test procedures if their product fails a test. One provision of the protocol states: "Inspect the head protector to ascertain whether it is suitable for its intended purpose and fulfils the general requirements in 4.2 (Construction). If no test method is specified in this document the compliance with the requirements have to be checked by visual and/or tactile examination." For ergonomics and comfort the protocol provides: "The head protector shall be placed on a test person representative for the actual head protector size and according to the manufacturer's instructions. The person shall check that, during normal use, i.e. bicycling according to the manufacturer's instructions, normal positions can be reached and movements can be done without any appreciable discomfort." These are all subjective judgments, not test methods for a standard that could be replicated by other labs.

The Swedish lab test protocol also specifies: When deployed, the noise level measured at the test dummy's ear shall not exceed 135 dB. That is above the threshold of pain. It may not do permanent damage to every rider's hearing, but will certainly startle the rider and be disruptive, particularly if the deployment is unnecessary.

We do not know of any other published standards available to assess those elements of inflatable headgear. The research conducted at Stanford and attached to the petition as evidence noted the importance of the sensors' performance, and concluded that "However, before this technology becomes widely available, airbag helmets need more reliable impact triggering technologies and should be evaluated in more realistic bicycle accident simulations." [1]

Airbag design problems

To protect against head injuries the headgear must be in place between head and hard object at the moment of impact. That requires an inflatable headgear to be inflated prior to the impact. If the airbag deployment mechanism is not functioning for any reason the rider has no protection. If the wearer has not turned on the switch, or the batteries are depleted, or the sensors fail, there will be no protection. In addition, any impact that does not involve typical motions of a fall will not trigger inflation. The airbag would not be inflated for impact with the overhanging back of a truck, an overhanging tree limb or low bridge, for example. Cyclists also encounter vertical hazards: stanchions, utility poles, bridge abutments, motor vehicles, trees and other elements in their environment where the first impact to the head can occur before a fall or other change in head direction. And finally there are moving hazards in the form of large mirrors on motor vehicles that can overtake a cyclist and strike their head from behind without warning. In all of these cases a conventional helmet will be in place at all times, while an inflatable will not be in position to manage the impact.

The most devastating crashes would not involve any deployment of the airbag prior to the impact, even if the deployment mechanism were 100% reliable. That level of reliability is highly unlikely, and the speed of deployment may or may not be adequate. A conventional helmet is already in place. This Youtube video if halted at the right moment shows that had the stunt rider's wheel encountered the bench only a short distance further along he could have hit his unprotected head on the stanchion before the Hövding inflated. Here are two photos from that video and a companion video with a different point of view of the same stunt:

Stuntman flies through the air, Hövding not yet open

Same stuntman from another point of view, Hövding not yet open

The next frame would show the Hövding just beginning to inflate. In numerous other demonstration videos found online the stunt riders carefully avoid any contact with a stanchion other than with their shoulder or a part of the bicycle, since a direct head impact would be unprotected by any airbag deployment and very likely to cause serious injury.

A reactive inflatable may not be in position when an impact occurs. The Introduction to the Swedish lab test protocol included with the petition states: "When an inflatable head protector is used in normal bicycling there is no protection against a direct hit to the head. Also the head protector offers limited protection against pointed objects." It also notes that it "offers limited protection when the head protector has only partially reached inflated status prior to head impact."

Videos of the lab tests for the Folksam article attached to the petition show considerable rebound after impact with the Hövding, which may increase the change in velocity of the head (delta V) more than a conventional helmet. There have been suggestions recently that helmet standards should include measures of delta V because it is suspected to be an important element in concussion. As noted above under Headforms, the Folksam article included in the Hövding petition recommended further research on the effect of testing with a neck during longer impact sequences.

Once inflated the shape of the airbag and it's extension from the head could complicate any injuries, particularly if the bag snags on an object before or after impact. The zipper holding the Hövding around the neck and buckle for the on-switch is complicated and difficult to access when the airbag is inflated for a third party not familiar with it, possibly making it hard for first responders to remove the device, as shown by fumbling in this video even though the wearer is upright and standing still. There is no test for that parameter in 16 CFR 1203 because conventional helmet buckles are easy for first responders to see, reach and unfasten without disturbing the rider's head or neck position.

Once inflated, the Hövding might not pass peripheral vision requirements of 16 CFR 1203. That could restrict the rider's ability to manage a crash, particularly if the Hövding has deployed unnecessarily and no crash has yet occurred.

The petition says the Hövding is not designed for mountain biking, but it would be used for that activity if sold here. The manufacturer does not expand on why the device can not be used for mountain biking, scooters, roller skating and more.

Battery life
We think the nine hour maximum between battery recharges will prove too short for some riders, who may not begin a ride with the battery fully charged and are likely to finish a ride after the battery fails without a functional airbag. Since most batteries lose some capacity with time, that could become shorter still as the battery ages. An airbag device left on a shelf for two or three years might well have a dead battery and could not be used until charged.

The petition says the company is aware of only one incident where the Hövding did not deploy as expected. A quick search of YouTube videos shows:
These videos provide an indication of failures of the device, again bringing up the judgment in the research paper attached to the Hövding petition: "However, before this technology becomes widely available, airbag helmets need more reliable impact triggering technologies and should be evaluated in more realistic bicycle accident simulations." [1] The research paper also notes that "..deploying the airbag in an unwarranted situation could be dangerous.."

In the U.S. we still require seatbelts in airbag-equipped cars. Airbags in a car are considered supplementary protection. That could apply to headgear as well.

Other considerations

The law directing CPSC to adopt a bicycle helmet standard (CONSUMER PRODUCT SAFETY ACT BICYCLE HELMETS [Sec. 205 of Public Law 103-267, 108 Stat. 722, June 16, 1994]) that requires bicycle helmets to meet the CPSC standard to be sold in the US market was a major victory for consumers, requiring consumer organization lobbying to have an act of Congress passed. The law does not mention anywhere granting authority to CPSC to make exceptions to the helmet standard. We believe it would be unfortunate and could be illegal for CPSC to grant an exemption from that legally-mandated standard to accommodate a manufacturer whose product cannot meet the standard.

The requested action would approve a new standard for one product that does not provide equivalent protection to that of helmets compliant with 16 CFR 1203. CPSC has not previously issued waivers to the regulation, and could expect other requests, including folding helmets, recyclable helmets and helmets made from recycled materials for example. The second wave of airbag headgear could include inexpensive competitors with low-grade design and quality control, and apart from meeting the Swedish lab test protocol suggested by Hövding they may have inferior performance.
We recommend that this petition be denied on grounds that it seeks approval of a device with a lower level of protection than conventional helmets certified to 16 CFR 1203.


[1] Stanford News https://news.stanford.edu/2016/10/03/stanford-researchers-show- air-bag-bike-helmets-promise/

[2] Modeling and Optimization of Airbag Helmets for Preventing Head Injuries in Bicycling, Kurt et al. Annals of Biomedical Engineering, Vol. 45, No. 4, April 2017 (_ 2016) pp. 1148-1160 DOI: 10.1007/s10439-016-1732-1 (included with the Hövding petition)

[3] Råd&Rön article on Hövding - English translation

Here is The Hövding petition to CPSC for exemption

For access to background documents or comments received, go to: https://www.regulations.gov, insert docket number CPSC-2018-0003 into the "Search" box, and follow the prompts.