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Arai Quantum-X Review

Round Heads Rejoice!

Arai Quantum-X
Arai Quantum-X Review Summary
Review Summary

The Arai Quantum is back!

Round-heads, earth-shaped heads and “bulb” heads finally have a helmet that fits.

It’s been a long time — nearly 7 years — since Arai had a “Round Oval” helmet in their U.S. lineup.

The last Round Oval helmet offered by the Japanese company was the Arai Quantum II (review), discontinued in 2010.

Change comes slowly to Arai and the Quantum-X looks and feels similar to the original Quantum.

But it features the latest generation of Arai goodies that were first introduced on the Arai Corsair-X (review).

Included are the new side plates and visor removal system; the new visor lock with city defogging position; new top vents and a big new chin curtain.

Another bonus: eyeglass wearers should also have no problem fitting your specs in the wide Quantum-X brain chamber.

The Quantum-X is something of a paradox, because it’s a lot of the same with just those few updates.

One thing hasn’t changed though: the price.

Round-heads don’t have a choice though and the most basic Quantum-X shown here in white lists for $679.95 with a street price around $612.00.

When nothing else fits — and nothing else does for me — the Quantum-X is like a gift from the gods.


We’ve now reviewed every Arai helmet made, multiple times.

 And every Arai helmet looks like an Arai, feels like an Arai and performs like an Arai. Which means that if you’re looking for the latest in helmet fashion, you won’t find it here.

Look up the definition of the shop-worn phrase “If it ain’t broke, don’t fix it” in the dictionary and you’ll see a photo of an Arai helmet.

Change comes slowly and then only with minor updates to relatively minor features like the top vent shape and the side pod design.

The basic shell design, construction and appearance (other than graphics) hasn’t changed since, well, since we’ve been reviewing Arai helmets.

Since webBikeWorld has been around for 17+ years, that’s a looong time.

If you want fast change and cutting edge design, go see Shark. But if you’re interested in solid, proven performance, Arai is it.

Boring? Maybe. But when your head is bouncing along the pavement, you won’t be thinking about boring…

Paint, Graphics and Overall Quality

The Quantum-X has that same solid feel as any Arai helmet, although you won’t notice that this is the new Quantum with the long-lost Arai “Round Oval” shape just by looking at it.

This one is the most basic color you can get: solid white. It’s not even the “Diamond White”, which is white with a bit of metallic thrown in for depth.

But the paint and assembly are all top-drawer, so nothing to complain about at all.

Everything looks and feels just as it should though and there’s no one that gets the solid click feel of the top vents and chin vent like Arai.

These are not your cheap-feeling moving parts like you’ll find on sub-par helmets. When you click closed a vent on the Quantum-X, you feel it and you know it.

Arai helmets are pretty much all hand made, so this isn’t machine-made perfection and you can see evidence of the human touch here and there, in the way the vent holes are drilled and the seams of the liner.

There’s not much more we can say that we haven’t already in every other Arai review we’ve done. This is about the highest-spec helmet you’ll find and it feels different than anything else.

Score: The Quantum-X gets an “Outstanding” rating for paint and quality. See the Summary Table at the end of this page for a description of our rating system.

Arai Quantum-X Helmet Liner

Quantum-X Fit, Shape and Liner Notes

The “Round Oval” Internal Shape

The new Quantum-X has the old Arai “Round Oval” internal shape, missing from the lineup since the demise of the Quantum II.

Arai says the Round Oval shape is “Shorter front-to-back and a little wider side-to-side” when compared to the Intermediate Oval.

It definitely is wider side-to-side than any of the other internal helmet shapes in the Arai lineup and that’s the best news possible for us round-heads.

However, I don’t notice much difference in the front-to-back shape when compared to the “Intermediate Oval” shape in the Corsair-X or the Arai Defiant Pro Cruise (review).

There’s still a bit of room in the forehead of the Quantum-X, more than I remember from the old Quantum II. That’s not really a problem though, but I just wanted to let you know.

But, the Quantum-X does not have the short front-to-back outer dimensions found in the Corsair-X, where the chin bar nearly touches my chin. There’s plenty of room in the Quantum-X, so that isn’t a problem.

[UPDATE: The new Signet-X (review) is nearly identical to the Quantum-X, but the former has the Arai “Long Oval” (“Narrow”) internal shape and a slightly different top vent design.]

Quantum-X and SHARP

There was some controversy because the Arai Europe helmets known as the Quantum and Quantum ST had problems meeting the side impact protection test in the SHARP regime.

But the European Quantum and Quantum ST were not the same as the Quantum II sold in North America.

Nevertheless, Arai has added the “Peripherally Belted Super Complex Laminate Construction” to the Quantum-X, which apparently is a reinforcement around the sides and base of the helmet.

It’s not clear whether the Quantum-X will be sold in Europe and if it is, how it will fare in the SHARP tests.

Helmet Fit

The Quantum-X in size XL fits as expected for an XL. Again, you need to have a round shaped head to make this work, although some “Neutral” head shapes would probably fit also.

For more information about head shapes, please read the wBW Motorcycle Helmet FAQ page.

Eyeglass Fit

The wide Round Oval shape makes it easy to fit eyeglasses.

In fact, there’s almost too much room for my Randolph Engineering Aviator sunglasses (review)with their straight temples, designed to fit inside a helmet!

But that’s because I have another helmet fitting problem: I’m between a standard size L and XL. Size L is usually too small and size XL too big for my bulb head.

Liner Comfort

Arai helmets are typically among the most comfortable made and the Quantum-X is no exception.

The liner and cheek pads are fully removable. The padding is thick and the anti-microbial treated liner fabric feels plush.

Once Arai gets going with the optional cheek pads and liners, you’ll be able to custom-fit your Quantum-X even more.

The Quantum-X has a relatively complex liner system, with variable shape foam pads attached under the liner to help create the fit.

Bottom line: if you’re a round-head, there’s no other helmet like it. The Quantum-X is the one you need.

Again, for more information about head shapes and choosing and fitting a motorcycle helmet, please see the wBW Motorcycle Helmet FAQ page.

As always, remember that helmet fit is crucial to safety and comfort, so make sure you try the helmet on before buying, and try a variety of sizes. The smallest size that fits comfortably is usually the safest.

Arai RX-Q Internal Shape

Score:  We give the Quantum-X an “Outstanding” for a comfortable fit, a nicely constructed and comfortable liner with comfortable liner material.

Arai Quantum-X Emergency Cheek Pad Pull Tabs
The emergency cheek pad release pull tabs were hidden under the chin curtain on our helmet. Make sure you pull the tabs out far enough so the “EMERGENCY” label shows so that emergency crews will be able to see them.


Quantum-X Replacement Liner?

I’m waiting for Arai to release the optional liners and cheek pads for the Quantum-X.

As of November 2016, they’re not yet available. As soon as they are, I’ll opt for the thicker liner, which should give me an even better fit at the forehead and sides.

If you’re between sizes like me, it’s usually better to go with the larger sized helmet and then buy the thicker liner. This gives you more padding and usually makes for a more comfortable helmet.

If you get the smaller size and try a thinner liner, you won’t have as much padding and comfort can suffer.

Cheek Pads

It’s not apparent at first how to remove the cheek pads from the Quantum-X.

In fact, the emergency release pull tabs were completely hidden on our helmet and we didn’t find them until we were searching around, trying to figure out how to remove the cheek pads.

So there are two issues here: first, it’s not immediately apparent how the cheek pads on the Quantum-X can be removed, so be careful.

Second, make sure the emergency pull tab label is showing. Not only is this important, but you can use the emergency release pull tabs to remove the cheek pads.

Dig around underneath and you’ll find the orange labels. Be careful though — don’t just start yarning on anything and everything as you’re trying to dislodge the cheek pads.

Also, make sure you look and study carefully how they’re installed, what holds them in and how they are re-inserted. It’s not the same as most helmets, you’ve been forewarned.

When the cheek pads are reinstalled correctly, make sure that the “EMERGENCY” label is just visible, otherwise no one will know about it.

Arai Quantum-X Visor Removal

Face Shield, Eye Port and Visibility

The Corsair-X introduced a new Arai face shield design with a completely revised attachment system and it’s now included on the Quantum-X.

The points at which the face shield rotates on the sides of the helmet have been lowered and the infamous Arai side pods that have given so many street riders fits have been reduced in size and also completely redesigned.

Arai says that the changes create more smooth helmet shell surface area in the section above the side pods, which helps prevent anything on the helmet from catching or snagging obstructions during a crash and slide.

The eye port on the Quantum-X seems about average in terms of outward visibility.

It’s slightly smaller in both the vertical and horizontal planes than the Corsair-X, which is specially designed for racing in a tucked sportbike position.

New Visor and Side Pods

The operation of the newly redesigned face shield system and the revised removal system was described in our Corsair-X review and is fully illustrated in the video below, so be sure to watch it.

The side pods now easily release with the push of a lever and the face shield rotating mechanism is then laid bare.

It’s very simple to remove and replace the new face shield on the compared to the older system.

By the way, the Quantum-X face shield still has the Arai “infinite” system for raising and lowering. It depends on friction to keep the raised face shield in place.

New Face Shield (Visor) Lock

The other new Quantum-X feature (also first introduced on the Corsair-X) is the face shield lock and catch on the lower left side.

It’s a rocker-type lever that pops the face shield off of the lock and allows a (very) small first opening for city defogging.

The system easier to use than the old stiff friction snap on older Arai helmets, but it takes some time to learn the new system and develop the muscle memory on the location and operation of the rocker.

The Quantum-X also comes with the latest generation “Max Vision” Pinlock insert and the face shield has a recess to hold the insert, although the recess is far enough out at the edges to remain unnoticeable.

You’ll need to install the Pinlock for any type of cool-weather riding, because the standard face shield has no anti-fog treatment at all as far as we can tell.

But don’t fret; the latest Pinlock inserts are excellent with no discernable distortion. It would have been nice if the Pinlock was installed by Arai at the factory though…

Arai RX-Q Visibility

Score: We’ll give the Quantum-X an “Excellent” rating for above average outward visibility and the sealing performance of the face shield.

Arai Quantum-X Top Vents
Arai Quantum-X Chin Vent

Ventilation Notes

Top Vents

Like the Corsair-X, the Quantum-X continues the Arai tradition for one of the most effective ventilation systems available in any full-face helmet.

 Arai has been experimenting — or evolving — the top vents on the last few helmet releases and the Quantum-X brings yet another new design.

These are angular-shaped scoops with a solid clicking two-position lever located on the outside of each vent.

Having to fuss with two levers rather than one is a bit of a bother and it will take a few tries before your hands figure out the lever location.

But one thing’s for sure: the top vents really work, bringing cool air down into the helmet.

Chin Vent

The Quantum-X chin vent hasn’t changed; it’s the standard Arai “sugar scoop” (or “feed scoop” for you ex-dairy farmers) type that pours air directly through the chin bar, through a mesh bug catcher and on to your face.

Don’t forget: be careful of how and where you mount the microphone for an intercom system because the air coming through the chin bar vent can generate unwanted background noise in the speakers.

Exhaust Vents

The Quantum-X has a fairly standard (for Arai) rear exhaust vent array with a single lever for opening and closing a sliding cover over the dual vent holes.

It’s a two-position slider but position one (supposed to be half open) isn’t much different than fully open. This may be a production issue on our particular helmet.

No matter, because we always leave the rear exhaust vent fully open for business, 24/7/365.

There are two additional rear exhaust vents along the bottom of the helmet at 4 and 8 o’clock low.

Chin Curtain

The Quantum-X has a big, new, soft, nicely made chin curtain installed at the factory. It’s very nice and it’s effective.

The old pull-down vestigial chin spoiler is still there, underneath the chin curtain. Arai should eliminate it on their street helmets and save a few pennies.

Arai RX-Q Ventilation

Score: No doubt about it, the Quantum-X gets an “Outstanding” rating for ventilation. It’s among the best you’ll find.

Arai Quantum-X Chin Strap and Chin Curtain
New chin curtain but a continuation of the too-short chin strap padding.


Helmet Weight

The Corsair-V we reviewed in 2009 was a size XL and weighted 1758 grams. In comparison, the Corsair-X in size large weighed 1631 grams.

This Quantum-X in size XL weighs 1675 grams, an excellent result for a helmet that meets the DOT standard and is Snell M2015 certified.

For more information, be sure to visit the wBW Motorcycle Helmet Weights page for charts comparing the weights of all of the open-face, full-face and flip-up helmets we’ve reviewed.

Score: The Arai Quantum-X gets an “Excellent” rating for weight and balance.

wBW Video: Arai Quantum-X

Also: Arai Quantum-X on the wBW Vimeo Pro Channel

Noise Levels

Arai helmets aren’t always the quietest you’ll find, but their outstanding ventilation more than makes up for it.

The new top vent system on the Quantum-X is noticeably quieter than the old Quantum II, but you will hear some wind rushing noise when the top vents are open.

It’s about the same noise levels as the Arai Defiant and perhaps not as loud as the Corsair-X.

Close the top vents and the noise decreases almost to nothing.

Of course, this will all depend on your motorcycle, how the helmet fits and matches your head shape and any windscreen you’re using.

On a motorcycle with a windscreen that directs air right at the top 1/4 of the helmet, the open top vents will generate a lot of wind rushing noise.

But we always wear high-quality, correctly fitted ear plugs, so this is usually not an issue.

Note that our helmet evaluations are a combined effort of several riders over time on different types of motorcycles with and without windscreens.

Evaluators wear correctly fitted, high quality ear plugs (even when evaluating motorcycle intercom systems).

Always protect your hearing when riding a motorcycle. See the wBW Earplug Reviews for more information on choosing and wearing earplugs.

Note also that perceived noise levels will vary, depending on the individual.

Noise can be caused by many factors, including helmet fit, the type of motorcycle and windscreen, wind speed and direction and even the rider’s clothing.

For more information on helmet noise, visit the wBW Motorcycle Helmet Noise page.

Score: The Quantum-X gets an “Outstanding” rating for noise levels.

Intercom and Speaker Fit

The Quantum-X is one of the better helmet designs for fitting an intercom clamp, because there’s no fancy gasket molding around the bottom of the helmet shell.

The ear pockets are deep enough to fit speakers, but there is no specific speaker recess although there is a slight depression that can be felt under the ear pocket lining.

Arai Quantum-X Rear Exhaust Vent


The one issue we’ve been harping about on all of the Arai helmets is the length of the chin strap padding. It’s just too short!

We’re surprised that on a new helmet design like the Quantum-X, which is designed for street and touring, that this problem wasn’t resolved.

Safety Standards

The Quantum-X meets the DOT standard in the U.S.A. and it is Snell M2015 certified.

See the webBikeWorld report “ECE vs. DOT Helmet Safety Standards” for more information on the difference between DOT and Snell.

Also, here is information on the Snell 2015 standard.


The Arai Quantum-X is like a gift from the gods for round-headed motorcycle riders!

There’s nothing like it and the Quantum-X has all of the very latest Arai improvements and updates.

The icing on the cake is that it has among the best ventilation you’ll find in any helmet, period.

Like all Arai helmets, the only issue is the list price. But if you’re a serious motorcycle rider with a “Round”, “Earth” or “Bulb” shaped head, it’s worth every penny!

Also: wBW Arai Signet-X Review

wBW Product Review: Arai Quantum-X
Manufacturer: Arai Helmet Ltd. List Price: $679.95 to $829.95
Colors: Solids and graphics. Made In: Japan
Sizes: XS-2XL Review Date: November 2016
Shell Sizes: 2
Rating Scale is subjective: Unacceptable, Poor, Neutral, Very Good, Excellent, Outstanding.
Note: Item provided by a retailer, distributor or manufacturer with these Terms and Conditions.
Note: For informational use only. All material and photographs are Copyright © webWorld International, LLC since 2000. All rights reserved. See the webBikeWorld® Site Info page. Product specifications, features and details may change or differ from our descriptions. Always check before purchasing. Read the Terms and Conditions!


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