The AGV MS/ML sizes complicate things a bit further, as well. According to their size chart, MS is listed as 57cm, ML is listed as 58cm. Additionally, there is a jump in shell size between the two (at least there was for the K3 SV I tried on). I measure 57.5cm, right in the middle for most manufacturer's medium size. I first tried on the ML size AGV, and it seemed comfortable. Always wanting to make sure I had a snug, but not uncomfortable fit, I wondered if going down to the MS might work, and you get the smaller shell size to boot. Well, I could barely get that thing on my head. And once I did, I had a mild moment of panic that I would not be able to get it back off without a Dremel tool. My guess is the MS in their (AGV's) line is similar to the M/L example you gave for the Kabuto.
If it is a small spot like I have on my forehead, if doing soft foam work doesn't take care of it and you can get to the EPS, you can sand it a slight bit in the spot. Doesn't compress the foam and the sanding is relatively a small amount over maybe an inch in diameter and less than an eighth of an inch deep, probably more like 1/16th. Get some 80-120 grit and sand it a bit. Usually a remedy not for the main shape of the head, but rather for small imperfections in skull shape.
This is more informative than any "professionally" written article I've seen in 26 years of riding motorcycles (and reading about them). Thanks so much S21! Now off to measure my noggin. Maybe you can get one of the bike mags to publish your work....
Thank you for this very thorough article! After trying many helmets, I finally found one that fits. Now I know why, thanks to you. My head circumference is 58.2, and Cephalic Index is 81. The Schuberth C3 Pro (size Large) fits me best. Later, I bought a Medium liner for the Large shell. That feels even better.
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.
Ive been trying to find space for my "HORNS" for years. Like you I have 2 corners at the back of my head. I was about to pull the trigger on an Arai Quantum X for its roundness and adjustability. It also has gaps in the comfort liner where my "horns" would poke through. The Arai is already about to bust the bank for me, the Shoei even more so AND it looks better suited for the track than on my touring bike. Do you think the Arai could be adjusted using the techniques you described at the beginning of this thread? Or am I just throwing more money at helmets that I wont be able to make work for me? Thanks
Sorry for the slow reply. Arai helemet's liner can be adjusted in many different ways. As you mentioned, their (Arai) liner has space (gap) for the corners of your head. Their liner comes with two layers of removable sponge pad on each side of the head. I suggest checking Arai Astral X if you are interested in Quantum X. https://japan.webike.net/products/22778905.html (Astral X is the JDM version of Quantum X.)
Thank you! I just fixed a helmet that was sitting to low. Perfect fit just by putting a wadded-up skull cap in the top. Awesome thread, thanks for the help.
......I thought I was the unique one with corners at the back of my head. Where is a good place to purchase stick on 1/8” high density foam pads? Thanks in advance.
In post three there's a link. post three https://advrider.com/f/threads/how-to-solve-helmet-hot-spot-problem.1338421/#post-35873602 the link: https://www.foambymail.com/open-cell-foam.html Otherwise, Amazon or a old mouse pad
@S21FOLGORE I have a ratio of > 90. Is there any helmet that is DOT approved that will fit me? I ask about DOT given the insurance claim issue (if it becomes a factor in the future). I have an almost perfectly spherical head. Any tips for finding a good helmet? I didn’t know anything about helmet fit when I bought my first helmet, so I got stuck with a narrow fit helmet and I can’t ride for more than an hour without intense pain on the temples on the side of my head. I’ve tried the Arai Quantum-X, HJC CL-17, and Fly Trekker DS. I desperately want to get a custom fit helmet from Bell, but it appears the service is discontinued. I would have bought 2-3 helmets on the spot and kept them locked away to use over time if I made the cut off. Frankly, I didn’t know the program existed until after it was already stopped.
Shoei used to suit round heads best that I saw. Go to bike shops and shows to try on helmets, find what works.
The short answer is, if DOT approved is a must for you, the only helmet that I personally know that would work with CI>90 head is AGV AX-8 Evo (and Evo Naked). Go back to page to, and read post #22 and #28 https://advrider.com/f/threads/how-to-solve-helmet-hot-spot-problem.1338421/page-2#post-36123136 https://advrider.com/f/threads/how-to-solve-helmet-hot-spot-problem.1338421/page-2#post-36136554 No, SHOEI drastically changed internal shape of North American market model somewhere between X-11 and X-12. (or, just before X-11's release ). X-8, X-9, yes. (That was in the 90s...) Nothing in current line up would fit properly / comfortably on the head with CI >90. The only exception is X-14, which may work with after swapping comfort liner. (Thinner side pads, thicker front & back pads, thicker center pad may also needed ...)
Thank you for the informative reply, I will definitely look into the AGV AX-8. Do you know if the AGV AX-9 maintains the same internal shape? It appears as though the AX-8 is an outgoing model, I cannot find stock in my size. Thanks again!