Asian Americans who bike or skate know that helmets sold in America are generally not shaped properly for their heads. This is a phenomenon alien to most non-Asian people. Lately some brands have come out with so-called “Asian Fit” models. After an extensive research, I think these are just hot air, except for possibly a few exceptions.

Helmets sold in the US are molded to the average shape of European heads, roughly with a 1.3 ratio expressed in length over width of the head. In visual terms, you can picture a human head measuring 9″ from forehead to the back, and 7″ from ear to ear, shown below left. It’s got the shape of an oval, if you look at the head from top down. But Asians have a rounder head shape, with an average ratio of 1.16 instead. Picture a human head measuring 8 ¾” from forehead to the back, and 7 ½” from ear to ear, shown below right.

Most helmets sold in the US are sized by the circumference of a typical European head. A typical LARGE-size helmet targets an oval-shaped head with a circumference of 23″, or slightly larger. This LARGE helmet fits snug on a European head measuring 9″ long and 7″ wide, as shown below left. Often people order helmets online, based on advertised sizing charts. If an Asian American makes the mistake of buying a LARGE helmet thus, sight unseen, they will be disappointed. The helmet will not fit at all, as the sides of the helmet will be too narrow for an Asian head, as shown below right.

An Asian American will often need to order one size up, in order to get a helmet to fit. For instance, the same Asian American with a head measuring 23″ circumferentially will possibly need to order an EXTRA LARGE helmet shaped for a European head measuring 24″ circumferentially, as shown below right. Even though this helmet fits, it leaves large gaps in both front and back. The same EXTRA LARGE helmet on a European head measuring 23″ circumferentially will leave gaps all around, as shown below left.

After attempting to acquire an Asian-fit helmet yet again recently, I have come to a reluctant conclusion: there isn’t any helmet with a ratio remotely near 1.16 on the market, at least not in the US. Even the OGK Kabuto helmets sold in Japan, famously known as Asian-head friendly, do not come close to the 1.16 ratio. In fact, my conclusion is that only manufacturers that explicitly state a length-to-width ratio are honest about their helmets. And you can’t find them in the US market. All “Asian-fit” models available in the US hover between a ratio from 1.24 to 1.3. That is, they are barely any rounder than typical oval helmets. And none of them advertise information on length, width or ratio. In fact, most do not even show you a picture of the bowl, as such pictures are dead giveaways, revealing how these helmets are just regular helmets.

In most cases, helmets I found comfortable were simply helmets shaped for a typical European head. I usually bought one-size bigger than my head circumference would entail, given a manufacturer’s sizing table. This allowed the helmet to clear sides of my head. But it also left large gaps in the front and in the back. I then relied on a helmet’s adjustable strap to tighten the helmet against the back of my head, as shown below left. This does reduce the front gap a bit as well. On the other hand, I have never been able to get an acceptable fit with helmets that do not include an adjustment mechanism. There are always unsettling gaps at both front and back, as shown below right.

My helmets are shown below. The skating helmet on the left and the biking helmet in the middle have an adjustment dial. The hockey helmet on the right has an adjustment slider. They achieve the same. With the biking helmet in the middle, I move the dial to reduce the length by as much as 3/4 of an inch. As you can surmise, my head has a length-to-width ratio even lower than the average 1.16 of a typical Asian head. I don’t actually know whether this much length reduction results in degraded impact performance. But I trust that CPSC and ASTM certification processes take into account these dial adjustments. Or do they?

I made assertions earlier that so-called “Asian-fit” helmets available on the US market don’t actually make round helmets to the required 1.16 ratio. I have long harbored this suspicion, based on my empirical observations. But others have done actual measurements to prove it. If you want to conduct your own research, I suggest that you start with the best article online on the topic: Bicycle Helmets for Rounder Heads, from Helmets.org. You will get an idea about the landscape of so-called Asian-fit helmets. Then look at AngryAsian: Let’s rethink helmet sizing, where the table shown below is published. These are Asian-fit brands and models mentioned in the helmets.org article. I added the derived ratio column. I also added equivalent measures in imperial units for the US audience.

As can be seen from the table, these Asian-fit helmets have ratios ranging from European average (Bontrager Velocis at 1.325) to slightly rounder (Giro Aeon at 1.247). They are far from the Asian average of 1.16 ratio. I suspect people find them usable as Asian-fit helmets, not because of the small reduction in length-width ratio in some of them. Asian people find them usable, because all of them have adjustment dials or ratchets. That is, adjustment straps or equivalent mechanisms are what make helmets Asian-friendly, not some baseless claims about unique shapes.

Now I present to you measurements I took with the three helmets in my possession. But first, take a look, again, at that picture showing their respective bowls. They all fit me. I bought all three of them at brick and mortar stores, at different times. I tried them in person, and made sure they fit me, before I paid for them.

For the Thousand Heritage, I measured the length and the width of the bowl solely based on the EPS foam shell. I disregarded padding, adjustment straps, etc. These additional items do take up space, but I excluded them for simplicity and accuracy of measurements.

With the cheap Giant Talos, the adjustable strap surrounds the entirety of the helmet circumference. This is an inexpensive way to make a one-size-fits-all helmet. The helmet is labeled LG/XL. But it in facts works for medium and small heads as well – just dial in extra clicks on the adjustment strap. I measured dimensions of the shell only, excluding the strap.

With the Bauer Re-akt, however, the shell is almost completely covered in XRD foam. So I treated the liner as part of the shell for measurement.

Here are the measurements shown in a table similar to that from AngryAsian. Again, note that I measured the EPS foam bowls, and disregarded paddings and straps. This allows me to directly compare their shells, in terms of ratios. A number of odd things immediately present themselves. First, look at the “size” column. These are the helmets that best fit me, when I bought them in stores. I tried different brands, models and sizes until I found the most fitting ones. Yet, the three helmets are classified by manufactures as Medium, Extra Large and Large respectively. Sizing methodologies of helmets truly are all over the place. As mentioned earlier, Giant Talos has no specified circumference range, because it’s a one-size-fits-all model – the adjust dial does all of the work.

Thousand Heritage is the “roundest” helmet, with a 1.232 ratio. This is in fact rounder than the supposed “Asian-fit” Giro Aeon, at a 1.247 ratio. While the Thousand brand never advertises its helmets as roundish or Asian-fit, its Amazon reviews are full of non-Asians complaining how “round” this helmet is. I don’t believe that this helmet is “that” round, for a typical European head. The perception of roundness and gaps created on the two sides of the head is partly an illusion. This helmet “runs large”, in the words of company representatives who responded to user complains and questions. That is, their advertised sizing chart is a bit off, with respect to accommodated circumference measures. Many customers ordering this helmet online will find the helmet slightly bigger all around than expected. But European Americans can compensate for this easily using the adjustment strap, as shown below left.

Coincidentally or not, this slightly-off sizing chart happens to work well for Asian Americans. As I mentioned earlier, Asian Americans often need to order helmets one size up, with respect to specified circumference-to-size mapping. With Thousand Heritage, this is not necessary. The 1.232 ratio and the “run large” nature of its sizing chart make a Heritage helmet fit the width of a typical Asian head. To be sure, the helmet still leaves gaps in the front and in the back. This can be fixed by adjusting the strap, as shown above right.

To summarize, I think an adjustable strap on a helmet is a lot more important and useful to an Asian American than advertised “Asian fit”. Until someone actually makes a helmet with a 1.16 ratio, no helmet available on the market will naturally fit an average Asian head. If you are Asian, just get whatever helmet suits your style and your sense of fashion. Possibly buy one size up. Make sure there is a flexible adjustment system.

Collected measurements

I will continue to update the following table, as people report measured length and width of their helmets, using the same way described above. We’ll go by metrics in this table for simplicity.

Folding Helmets

Updated 2023-01-13. Ulrik from Newton-Ryder left a comment about their new N1 folding helmet. From their website this new helmet looks refreshingly stylish. It will certainly fit better for a wider variety of head shapes, including the Asian kind discussed here. If it performs well under certified tests, it probably take off much like the Thousand Heritage did. While many folding helmets are already available in the market, none folds like the N1. Perhaps folding helmets is another way to address the Asia Fit issue.