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Old 10-16-2018, 05:17 PM   #31
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Originally Posted by S21FOLGORE View Post
fig.1
Thank you for all this, I haven't read of all it yet, but what perspective are these diagrams taken from? From above the head, looking down at it?
If so, then it looks like 3 of them are basically the same thing. A forehead that's more narrow than the back of the head. Is it just a subjective difference, or are there actual numbers to differentiate them?

Last edited by Reli; 10-16-2018 at 05:24 PM..
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Old 10-24-2018, 09:56 PM   #32
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Yes, it is the shape of the head when you look from above.

Yes, the difference is totally subjective (especially the difference between short-oval and short-sub eliptical.)

Still, it is worth mentioning all these shapes for the purpose of this thread.

Now ...


Some important tips about “how to choose size” when purchasing helmet from overseas. (Meaning, you can’t “test fit” the helmet before placing an order.

The untold story of fitment, shell size and liner thickness.

(I’m going to use round heads (CI ≧ 85) as an example here. But, what I’ll explain applies to all type of head / helmet internal shape.)

Example story


[url=https://flic.kr/p/2chRMPa]

So, you are in between the sizes, S and M.
You have been advised by people on the internet forums and by people at the local shop.
“Go for a smaller size, because the helmet (internal) will break in / stretch / mold onto your head.”

You believed that advice and purchased size Small instead of Medium.

You go for a ride happily with a brand new helmet ...

[url=https://flic.kr/p/2cebRM7]

... and an hour later, you get unbearable pain on the side of your head ...

[url=https://flic.kr/p/29C2KfG]

Sounds familiar?

If you have been riding many years already, tried more than a few different helmets and still get the hot spot on the same area, then you are either ...


wearing the wrong shaped helmet

wearing the wrong sized helmet

... or, could be doing both ...


You came across this thread, and measured your head’s front-back, side to side, and it turned out that you have CI 88 head.

So, now you know you have two problems.

The first problem is CI.
The helmets that you can buy locally, or from Revzilla, STG, etc, are all designed for the CI<85 head.

Knowing that JDM Arai / SHOEI are CI 85-86 helmet as a standard (can be tuned for higher CI), you decided to give it a shot.

But now, you are facing the second problem.

You are in between S and M size.

Which one should you order?

For obvious reason, you don’t want to end up ordering the wrong size and shipping it back to Japan, reordering the different size.

How do you decide the size when actually trying it on is not an option?

4-shell size vs 2-shell size helmet

Would you be surprised if I tell you that, with some helmet, the fitting is quite different from size to size?

???

Let’s take a look at two examples.

SHOEI X-14 VS OGK Kabuto RT-33

X-14 4-shell size




RT-33 2-shell size


First, let’s take a look at X-14.
They come in 4 different shell sizes.
S(S and XS use the same shell), M, L, and XL (XL and XXL use the same shell).

fig.19

[url=https://flic.kr/p/2cjjSYQ]

The relationship between the shell, EPS liner, comfort liner, and the available inner space of the helmet is the same all across the sizes, except for XXL.

Except for XXL, all the helmet comes with 9mm thickness comfort liner as a standard, and you have options to go either thicker (+4mm) to make the fit tighter, or thinner (-4mm) to make the fit looser.

Each size of the helmet (except for XXL) has the same amount of tolerance / limitation for irregular bumps and slightly oversized head.

To put it simple, M is the scaled down copy of L, and S is the scaled down copy of M, they all have the same amount of space for fine tuning.



Now, RT-33, which comes in 2-shell size.

It uses the same shell for XS, S, and M. And L, XL, XXL share the same, bigger sized shell.

Now, look at the picture below, pay particular attention to the liner thickness and the helmet labeled size.

fig.20

[url=https://flic.kr/p/29Cb3bu]


Yes, you guessed it right.

Size XS, S, and M are THE SAME HELMET with different thickness comfort liner installed.
And size L, XL, XXL are the same helmet, the difference is just the comfort liner thickness.

With this type of helmet, it is a little bit tricky to choose the size.

If you happen to be between the S and M size, you should order S, NOT M.

You have 15mm thick foam surrounding your head, that’s a lot of cushioning, and it will tolerate the slightly oversized head (56.5 cm) without problem, even if your head has some irregular bumps, bulges, etc.

BUT, if you are in between M and L, then, you’d better get L.

Why? I don’t want a bigger shell size ! You just said “L” size helmet use the same shell as XL an XXL, that would make me looking like a bobble-head figure!!

Well, I (sort of) understand the feeling, but take a look at the fig.20 again.

RT-33 in size M comes with the 2nd thinnest (9mm) comfort liner. (thinnest being 5mm on XXL).

Size M comes with the least amount of tolerance(extra space), besides XXL, for irregular shapes and oversized head.

If your CI is 88 for example, and circumference is 58.5 cm, I can almost guarantee you that you are going to get painful hot spot on the side of your head if you wear size M.

IF. your head shape is slightly off (eg: CI 87, 88) BUT the correct size (between 57 and 58 cm), then M will work.

Or, if the head shape is correct (CI 85, 86) but circumference is slightly greater (58.5 cm), them M will work also.

However, when both the shape and the size are off at the same time, you can’t go for smaller size.

So, I hope you now understand the “multiple shell size” is NOT for the looks, but for function.

Also, I hope you understand now, that why some helmets cost more than the others.
(Just making 4 different sized molds for shell, and 5 different mold for EPS liner would easily make X-14’s production cost more than twice the production cost of RT-33.)



Oh, by the way, the same rule applies for multiple shell sized helmet, when it comes to sizing.

If you happen to be in between the sizes, you can go for a smaller one
ONLY IF your CI is close enough(±1) to the helmet’s target CI.

Otherwise, you’d better order the larger size.




One method that works (for only Arai and SHOEI) for size checking is to use genuine issue boonie hat.
Go to the military surplus store and try them on.



The brand doesn’t matter, as long as it’s made to proper specification which is MIL-H-44105B.

For example, the size 7 is 55.9 cm. If the size 7 feels too tight, but next size which is 7-1/4 (57.8 cm) fits alright, you should get M, instead S.
If 7-1/2 is too tight, you should get XL, not L.

You know, boonie hat does not stretch, so you should be able to tell clearly if it’s too tight.

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Old 10-25-2018, 06:30 AM   #33
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and I will be posting links to your thread all over other moto forums.


.
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Old 10-25-2018, 05:13 PM   #34
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Y
Would bang


Seriously though, thanks for the great work!
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Old 12-29-2018, 10:54 PM   #35
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Thanks for sharing this! Great descriptions AND illustrations!

FWIW, I think it could also be printed up and sold.
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Old 02-24-2019, 02:37 PM   #36
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SHOEI X-14

One last thing I may add.

Why SHOEI X-14 is so great, in terms of adjustability?

Because it offers more range of adjustment for many different types of the head shape.

You may have forgotten, but my head (looking from the back) has two corners at the top
(almost like I have horns on the back of my head.)

Well, the hair is deceiving. It covers the corners, the irregular bumps on the head.



(It also (kind of) acts as buffer zone, between your helmet and skull.)

It looks goofy, but this is how the center pad sits on your head.



If you are having hot spot problem and trying to fix it, then, you really need to take off the liner and wear it,
look into the mirror, figure out which part is pressing hard on your head.

This is the most important for my particular head.
See the gap between the top pad and the side pad (where I am pointing)?



This is how mine is set up.



See the huge gap there? That’s where my horns go through.



Now, if I close that gap there, like this ...


... then, it will give me some very annoying pressure point ...



... even though it is exactly the same helmet with the same liner ...

If you ever decide to try X-14, don’t disregard it just because it doesn’t fit exactly right
when you first try at the shop (or purchasing from online store.)

Pull out the center pad (which is very easy) and try closing / enlarging the gap between each pads.

You can also do it on the road side if you want to experiment.




Snap off one side at the back...



Snap off the other side ...



Pull the front portion out from the eye port opening ...



... can you see better?



Then, just pull out the entire center pad



No need to mess around with cheek pads or chin strap.
This is one of the best design out there.
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Old 02-24-2019, 02:51 PM   #37
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very interesting read. subscribing to find it later.
That. You deliver. I've seen those head caliper things before.
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Old 06-19-2019, 04:43 PM   #38
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About "replacing helmet after 5 years" thing

So, you have the helmet that you can happily wear for hours without pain, but doesn't slip around on your head.

Do you have to replace it after 5 years, as some people say?

I was kinda hesitant to post this, (because this may "open up the whole can of worms"), and it's not directly related to hot spot/ fitting problem.
,but, in the end, decided to post against my better judgment. (I originaly wrote this for ADV rider’s thread, regarding the helmet’s “sell by date”.)

First of all, I want all of you to understand that this is what SHOEI North Amarica, who is a distributor, NOT the actual helmet manufacturer, says.
(Yes, yes, I understand that for us who live in US and Canada, SHOEI North America IS SHOEI (since SHOEI Helmet in Japan won't directly communicate / do business with us), but still, you have to understand that what they(SHOEI North America) say is NOT exactly the same as
what SHOEI Helmet in Japan (as a manufacturer) says.


Now ,...

Let's get clear about the fact that SHOEI North America NEVER said the helmet is not safe to use after 5 years from the date of manufacture.
What they say, is

Even if none of these is applied, we, SHOEI, recommend replacement in 5 years after it's first purchased at retail.

(exempt from here

Helmet Replacement
Ultimately, the useful service life of a safety helmet is dependent on the intensity and frequency of its use. Helmet replacement is recommended even if only one of the under-mentioned points applies:
1. The helmet was subjected to an impact.
2. The comfort padding or the retention system has become loose due to heavy use or display signs of deterioration. Test: with the retention system fastened, the helmet turns to the side when you gently shake your head.
3. The EPS liner has come away from the helmet shell.
4. The EPS liner shows signs of wear and is beginning to break up, or if it has been exposed to heat or a solvent and has melted. There are indentations in the EPS liner and/or white scratches can be seen on surfaces with black paint.
5. Even if none of these is applied, we, SHOEI, recommend replacement in 5 years after it's first purchased at retail.  )

The "5-year" time frame is NOT based on the research (of how much deterioration happens over the years).
It is decided that way for the sake of convenience (5-year limited time warranty).
(Arai North America, Schuberth North America, they all do the same. 5-year limited time warranty, recommending the helmet replacement after 5 years of use.)

You know what Arai and SHOEI (and OGK) say, in Japanese domestic market?

Let's take a look at the manuals of JDM version.




Arai







SHOEI





Yes, I know you can't read them.
But, you can see "SG" (SGマーク= SG mark = SG sticker) in both Arai and SHOEI's manuals.
You can also see "3" in SHOEI's manual.
(In Arai Manual, it is writeen in Kanji character,  "三" (means 3)).

What they are telling you is that they recommend to replace the helmet
AFTER 3 YEARS from the date of purchase.





Yes, 3 years.

They are telling their customers in Japan to replace their X-14 after 3 years from the date of purchase.

WHY?

Because of these.



Close Up












Can you see this ?



This is the sort of "insurance" system they have in Japan that expires after 3 years from the date of purchase.

These things have "SG sticker" ...



These things (folding walking cane) have SG sticker ...



They (the manufacturers of motorcycle helmet, boys baseball helmet, walking canes ) have to pay fairly huge amount of money and get their products certified. Otherwise, the products cannot be sold as "motorcycle helmets" or "baseball helmets" or "walking cane".
(Without certification and SG sticker, these things can be sold only as "for decoration", it's illegal to sell them as motorcycle helmet / baseball helmet / cane / cooking pot / whatever ....)

So, they tell their customers (in Japan) that they recommend to replace the helmet after 3 years, based on this system.
Not because the helmet gets deteriorated and becomes unsafe after 3 years.



As far as I could remember, this (3-year time frame for recommending helmet replacement) has not changed from all the way back to the early 1980s (when I started wearing motorcycle helmet).

So, the helmet manufacturers NEVER said the helmet is unsafe to use after 5 years from the date of manufacture.
The distributors (SHOEI North America, Arai North America, Schuberth North America, etc etc) NEVER said that either.
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Old 06-19-2019, 04:55 PM   #39
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