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Motorcycle Helmet Head Shapes

Hohenstein Institute Head Shape Study Confirms the
Differences and Importance of Motorcycle Helmet Internal Shapes

March 20, 2013 – It was more than 10 years ago when we first described the differences in head shapes and the relation to motorcycle helmet fit in the webBikeWorld Motorcycle Helmet FAQ.

Our findings were not based on scholarly research, but rather on practical experience with the many motorcycle helmets that have passed through here for review.

In all this time, there is only one motorcycle helmet manufacturer who specifically makes helmets to fit different head shapes, and that manufacturer is Arai.

The internal shapes made by Arai are very limited, but the company at least recognizes the proven fact that there are difference in human head shapes, ranging from “Long Oval” to “Round Oval” in the Arai parlance.

Head Shape Variations
The 6 different head shape variations from narrow to round.
Head Width Variances
Head width and shape variances example for a 58 cm circumference head.

Why other manufacturers don’t recognize that there are real differences in human head shapes, and make motorcycle helmets to match is unknown.

In fact, some manufacturers won’t even admit this issue exists, most do not state the internal shape of their helmets and others don’t even acknowledge that their helmets are made to any particular shape. Strange, indeed.

We have always maintained that motorcycle helmet fit is — next to meeting the safety standards — the most important factor in a motorcycle helmet. The “best” helmet in the world is useless if it doesn’t fit correctly and, in fact, it could be less protective in a crash than a “cheaper” helmet that fits correctly.

The Hohenstein Institute Head Shape Study

If motorcycle helmet manufacturers needed any more proof that this problem must be addressed, the research of Dr. Jan Beringer of the Hohenstein Institute should convince them.

Dr. Beringer discussed the head shape issues and his ongoing study during a recent live webcast, which was announced on the webBikeWorld Facebook and webBikeWorld Google+ pages.

That webcast, which was recorded live and is available on the Hohenstein Institute website for downloading and viewing was very interesting (the slides without audio are also available in this .pdf document).

Dr. Beringer used 3D scanners to map the head shapes of many volunteers and has found six different general head shapes, from narrow to round.

Of course, one of the main inferences of this study is that motorcycle helmets should be made with different internal head shapes to match the human head shape categories.

The study also demonstrates that when a helmet’s internal shape does not match the wearer’s head shape, the resulting space between the helmet padding and the head can result in less optimal protection for the rider. A misalignment can also cause pressure points, resulting in an uncomfortable fit and distraction for the rider, another safety issue.

3D Distance Analysis
Protection may decrease when a helmet doesn’t match a head shape.

Dr. Beringer said that his “sizing survey showed remarkable variations in head shapes within the same head circumference” and that “additional high-resolution anthropometric head data is needed, in particular shape information”.

He also stated that “Industry standards do not comply with the state of technology any more; head shape information is missing totally” and that the “Influence of hair on the size measurements and helmet fit is unclear”.

For more information, watch Dr. Beringer’s 32-minute webcast recording (.flv format) and follow this study as Dr. Beringer continues his research.

We can only hope that the motorcycle manufacturers will take notice and interest in this important fact and begin to make motorcycle helmets in more shapes, which would not only improve comfort and wear rates but may also help reduce head injuries.

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From “S.P.” (March 2013): “One can order custom boots or orthotics online and they send you a box with crush foam in it, to get an exact mould of your foot. Seems to me that a clever helmet manufacturer or third party could do the same — send an appropriately sized box with two halves of crush foam and presto, custom fit! Talk about lifelong customer loyalty too!

Once they have scanned my head size and shape in an AutoCAD file, I can continue to get helmets from them as the years go by… How hard can this be? C’mon Arai, Schuberth, Shark…!

Rick’s Reply: the reason this isn’t done is because each helmet would have to be re-homologated to DOT, ECE, etc. standards whenever the internal shape of the EPS changes.

Although, the internal shapes can be customized to a certain extent by changing the padding inside.

For example, Arai offers this option on most of their helmets; the basic internal shape doesn’t change, however, so swapping out the padding can’t change a “Long Oval” into a “Round Oval”, but quite a bit of customization can be done to the fit.

Reply From “S.P.”: “Good point! There must be some way to utilize such individual head shape info to customize the helmet; in other words, Arai could definitively tell you what shell shape (model), and provide exactly the correct padding and placement for a superb fit. With the technological advances in 3D scanning and printing, I hope it becomes a reality in the near future!”

Rick’s Reply: Yes, a good Arai retailer can do that, although not with a scanner. In theory, any good motorcycle retailer who knows their business should be able to help with finding the correct helmet fit. Unfortunately, those are few and far between…

From “K.P.” (March 2013): “It is so hard to find a round internal shape helmet. How about a review for the Fly Paradigm helmet. It is one of the few that seem to fit. The Speed and Strength SS1100 and SS1000 seem pretty good also, but no reviews yet. I’m not sure how you get helmets for review, but these are a couple I would like to see.”

From “R.K.H.” (March 2013): “J.W. wrote in a comment (below): “When I read one of your helmet reviews, the first thing I do is scroll down to the “internal fit” paragraph and if it’s not my head shape, I stop reading. For the same reason, I don’t read helmet reviews in other publications.”

I also look at your ratings of the internal shape. As someone with a round head, Arai Quantum II (review), it would be nice to have some options. As it is, Arai doesn’t seem to make anything that’s as round as the Quantum II now. Nor does anyone else.”

From “J.W.” (March 2013): “I, too, am at a loss to understand why not only manufacturers but other publications that review helmets, fail to talk about head shape.

When I read one of your helmet reviews, the first thing I do is scroll down to the “internal fit” paragraph and if it’s not my head shape, I stop reading. For the same reason, I don’t read helmet reviews in other publications.

FYI, I’m on my second Shark RSI (review). The fit is perfect (snug but perfect) and I’ve put in 10 hour days with no problem, at least in the helmet department. Thanks for your very helpful reviews.”

  1. Please help me find a helmet or find a way to Diy measure my head shape! I have 3 helmets for my use:

    Nolan n102 – M – which you say is round- fits very well – noisy – old
    Schuberth S1 L – pretty large – silent – interior fade quick
    New Scorpion exo 510 Air L 60 – press my forehead and back of the head – large on my ears zone – noisy and whistling air vents – bad visor sealing( improved after some adjustments)
    extra : 1 rueger size M which got my eyeballs out 😉

    Is there a way or can we find a way to empirically estimate the head shape? I recently had a MRI scan by the way 🙂 so its alll measured!
    Thank you for your time!
    P.S. I dont have where or models to try, local shop brings only few and … at the meetings i feel ashamed to start asking for testing helmets! I can order on internet but i should probably do my lessons before!

  2. Measured 58,5cm around the head as indicated, 20.4 long to 15.1 wide(made a some sort of crown)! My head profile fits the second picture from Head shapes variations picture while the “crown ” shape fits the first picture but a little more square-ish!

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