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.
| Helmet | Size | Circumference Accommodated | Measured Length | Measured Width | Computed Ratio |
| Bontrager Velocis | S | 51 – 57cm (20 – 22.4″) | 212mm (8.35″) | 160mm (6.30″) | 1.325 |
| Giro Aeon | S | 51 – 55cm (20 – 21.65″) | 202mm (7.95″) | 162mm (6.38″) | 1.247 |
| Louis Garneau Course | S | 52 – 56cm (20.47 – 22″) | 207mm (8.15″) | 164mm (6.46″) | 1.262 |
| POC Trabec | S | 51 – 54cm (20 – 21.25″) | 207mm (8.15″) | 163mm (6.42″) | 1.270 |
| Specialized Propero II | S | 51 – 57cm (20 – 22.4″) | 213mm (8.38″) | 163mm (6.42″) | 1.307 |
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.
| Helmet | Size | Circumference Accommodated | Measured Length | Measured Width | Computed Ratio |
| Thousand Heritage | Medium | 57 – 59cm (22.44 – 23.22″) | 219mm (8 ⅝”) | 177.8mm (7″) | 1.232 |
| Giant Talos | LG/XL | (unknown) | 231.77mm (9 ⅛”) | 184.15mm (7 ¼”) | 1.258 |
| Bauer Re-akt | Large | 59.5 – 64cm (23.42 – 25.2″) | 209.55mm (8 ¼”) | 161.93mm (6 ⅜”) | 1.294 |
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. Most of these are reported on Reddit. Some are from comments at the bottom of this article.
| Helmet | Size | Circumference range (cm) | Length (mm) | Width (mm) | L/W Ratio | By | On |
| Thousand Heritage | M | 57-59 | 219 | 177.8 | 1.232 | me | 7/18/2022 |
| Bauer ReAkt | L | 59.5-64 | 209.55 | 161.93 | 1.294 | me | 7/18/2022 |
| Kask Utopia | M | 52-58 | 206.37 | 171.45 | 1.20 | u/thatonedayinmay | 7/22/2022 |
| Kask Protone Icon | M | 52-58 | 206 | 171 | 1.20 | u/thatonedayinmay | |
| Lazer G1 MIPS | M | 55-59 | 212.73 | 168.27 | 1.264 | u/thatonedayinmay | 7/22/2022 |
| 2022 Specialized Prevail 3 Round Fit | L | 58-62 | 236 | 181 | 1.30 | u/ktula | 11/07/2022 Singapore |
| 2023 Bontrager Starvos WaveCel Round Fit | M/L | 55-61 | 215.9 | 177.8 | 1.214 | u/czhanghm | 4/21/2023 |
| 2019 Giro Aether Asian Fit | M | 55-59 | 207 | 178 | 1.162 | anon-comment | 7/4/2023 |
| Lazer Sphere MIPS (Fit-All) | XL | 61-64 | 231 | 190 | 1.216 | JunJun | 3/2/2024 |
| TSG Asian Fit Evolution | S/M | 55-57 | 225 | 175 | 1.285 | melty | 4/26/2024 |
Updated 2024-05-02. There is a reason why measurements shown above have dates associated with them. Helmet models evolve over time. Even the same brand or possibly the same model will change over time. For instance, the Thousand Heritage helmet have undergone changes. As of 2024-05, the Heritage 2.0 helmet appears to be more oval now, possibly due to overwhelming customer feedback, from folks who don’t have round head issues.
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.
Xinhai Dude 
Hi, I got the TSG Asian Fit Evolution helmet today. It’s targeted toward skaters, but it was being sold in an electric scooter and electric bike shop. It’s 22.5cm long and 17.5cm in S/M size. That’s a 1.285 ratio, which is nowhere near the average round head shape. I put 3 extra XS pads inside because I have an extra finger’s width in the front and almost as much in the back. My finger is just over 1cm wide. I also have extra space on the top (I either have horns from having a flat head from when I was a baby, or it’s just not accommodating to the average round head at all – or both). It’s $90 CAD, so this may be my only choice, as I can’t afford to spend $150+ just to pay to ship it back if it doesn’t fit. The store I got it from gave me an extra set of XS pads for free to help with the gaps. The helmet comes with an extra set of S/M pads already, but adding those onto the ones already attached to the helmet leaves too little room for my head. If I wear this helmet for a long time, I’ll have to buy an extra set of XS pads.
Just for a little extra info, I couldn’t get my head into the regular skate helmets (TSG, Triple 8, Protec) in S/M, whereas L/XL sizes were big all around, still without the top of my head touching the helmet. I really don’t have a big face, so my temples are free from pain so I can’t comment on that. But looking from above, my head is pretty round, and I think it’s just above the average Asian head ratio (maybe 1.9?). I AM concerned about the helmet sitting low enough, since in skating it’s more important to have low fitting coverage.
Asian fit skate helmets are even more rare, so I wanted to add this extra info to help anyone else who could find this useful.
Also I look a little silly because the front sticks out so much. But safety first (I’m 28 so I don’t care about looking cool anymore). Haha
OH and their circumference sizing is 55-57cm.
I know this is a lot of commenting, but I’d like to make a correction to my original post and an update.
The XS foam pads they gave me was actually thicker than the extra set of S/M pads that came with the helmet. The extra set is a little thicker than the ones already stuck on the helmet. I used the thicker XS foam in the back, the S/M foam on the top and front.
After 30 minutes of wear to test if I’d feel squeezing on my temples, I did experience that. Therefore, I will return it and go back to the drawing board.
For reference, my head circumference is 54.5 cm.
Thank you for updating your comments. You are obviously one of us who do not give up. And you write down observations. It’s of great help to all.
I’ll add a row to the table later.
I added a row with info you posted.
How do you want to attribute it to you? Give me a handle/label. See what others gave me in the table.
I never did think about the gap between the top of (the inside of) the helmet, and the top of my head. Yeah. Now that I think about it, in an accident, that simply reduces contact area with my skull to a small number of contact points. But hopefully with inline skating, I am not likely to get impacting forces from the top.
melty would be great as my handle.
Yes, it’s rare to fall on the very top of the head, but increasing contact points can be done with a little extra padding if you’d like. That was exactly my concern.
I ended up with the Thousand Heritage 1.0 in size medium, dialing it in the back with some padding at the top. I also tried on the 2.0 and found that the 1.0 has a more rounded bowl shape instead of a cone (not as pointy) compared to the 2.0 and other helmets. I talked to a worker at a bike shop and he commented that the 1.0 fits his round head better than the 2.0. He told me the founder is Asian, so she probably made the first iteration fit her head more. The 2.0’s “diverse fit” (as advertised) is to extend to oval head shapes. I wanted to mention that because after reading their marketing, it seemed like it was the other way around. Asking Google gave me the wrong answer, too.
Speaking of recording observations, your article is a great hub for us to band together and help each other. It’s given me enlightenment and I now know it’s not just me.
(Also I’m thinking that if all of us email Thousand to create a helmet with the 1.0 fit and the 2.0 features in the 2.5, they might actually do it)
Thank you. I added a paragraph next to the measurement table to warn people to double-check, and not just rely on what we report at the time we measure these things. There is a reason why I add dates and sources to every row. This allows people to understand when and where info comes from.
I added your handle : )
Trying to source bicycle helmets with Round Fit & MIPS or equivalent aspect ratio in all sizes.
purchased 5x s/m Bontrager Starvis Wavecell round fit
looked at m/l montage starvos wavecell round fit.
looked at recommended Lazer Sphere XL but want a cheaper option.
We rent out class 1/2 e-bikes and we noticed some of our customers opting for our largest helmets or just leaving them in their cars around the corner. We started noticing that certain helmets were more popular with said customers and here we are.
we read this site:
https://www.helmets.org/round.htm
we read the site we are on.
we watched a bunch of product reviews.
we are actively hunting for good round fit options.
updated recommendations would be helpful.
would consider choosing a brand that carries round fit and or has sizing guide with aspect ratio. We would deal them if overseas or wholesale with a us supplier.
we think MIPS like tech is cool, fidlock chin strap clasps are great, and the boa is good.
Thanks for your detailed comment about your long-term observation about what customers actually prefer, and do.
Note, however, that I am not recommending any helmets, since my data points are limited in scope. And the table of collected measurements from helpful folks is just, a table of best-attempt measurements by folks.
I think you are possibly at a better position to lend more data points : ) And you already have, by leaving this comment.
Thank you for this informative post. After being unsatisfied with how my old helmet fit for years, I started shopping for a new one and ended up here. Not sure how active you are with updating things but figured I’d add an extra data point for anyone that might come across this and find this useful. Since I have a large head, the Trek/Bontrager Starvos Round Fit was not an option for me.
After doing a lot of fruitless research, I ended up with Lazer Sphere MIPS. They don’t indicate this on any of their helmet’s product description as far as I can tell, but if you look at their product list and filter, there’s an option for “Fit” with options for Oval and All. I reached out to Lazer to clarify what “Fit-All” meant but only got a vague answer that it’s less oval than the rest. One of the reviews on Amazon stated this one was good for Asian fit, so I gave it a go. I’m happy to report the shape is great and a solid enclosure system makes for a comfortable and secure fit.
Lazer Sphere MIPS
XL (61cm~64cm)
231mm x 190mm
1.216
Thanks for the input. I try to update this page asap when someone gives me additional data points. But I want to note the source and date, as you can see from the table.
Give me a moniker to use for your row. I will use anon-comment2 for now : )
Thanks for the follow up, appreciate the thought! You can put it under JunJun.
Cool. I updated the table earlier already with your data. I just updated the attribution. Thanks!
Thank you so much for this article, very informative and useful guide
Can you checkout the Specialized Airnet MIPS which have Round fit version
This is a great idea, thanks for putting this together! To add my own data point, I have a Giro Aether Asian Fit helmet I bought in 2019 that measured out to be 17.8 cm wide and 20.7 cm long. Giro’s Japanese listing shows it fitting 55~59cm heads and confirms my 17.8 cm measurement: https://www.e-girotokyo.com/?pid=139355813.
Extremely happy with how this helmet fits, really disappointed that the new Aries doesn’t come in an Asian Fit and only has a “Global Fit” that’s claimed to be 16.8 cm wide fitting the same circumference head. Hopefully companies continue to make proper Asian Fit helmets, and, more importantly, start selling them in the rest of the world!
Thanks a lot. I presume that you have a “medium” helmet, judging by the 55-59cm figure you cited. The computed ratio of 1.162 is the most Asian-fit reported. I added a new row on the table based on what you reported. Cheers!
Hi Mr. Dude
Great story …we are solving this :)
best
Newton-Rider
NB/ Would you be interested to mention our helmet in an update story of your –one that we can post on our blog?
Ulrik, That is intriguing. Clearly a semi-soft, foldable helmet would fit better for a much wider range of head shapes. The N1 looks quite promising. If it offers the same certified test results as traditional helmets, this would be great news for all :)
Fred
I added a quick section to this article at the end, to mention folding bikes. It is a different way of looking at the Asian Fit problem. I took two online pictures of the helmet, and showed them against a common background to highlight the folded look/size. Hope you don’t mind.
Fred
this is racist
just kidding. great article
Ha ha ha. You know, only black bros can use the N word. And it takes an Asian bro to talk about Asian-fit helmets. Otherwise it would be eugenics and racist. Ha ha ha. Cheers.
Great article!