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Review: Icon 2006 Perimeter Domain helmet

When Icon presented us with the opportunity to try out their new Perimeter Domain helmet, we jumped at the chance. In our opinion, there aren’t many other helmets on the market that can match the aggressive styling of the Perimeter Domain. Not only are the jet fighter-like “supervents” a dominant feature, but the paint job also provides an assertive personality to this helmet.

In addition to the mean looking “supervents” and styling, the Perimeter Domain also sports a spoiler. We’re not talking a simple boot or lip style spoiler, but an actual horizontal airfoil where the wind passes on either side. The “dorsal spoiler” as Icon terms it, has never been used in a motorcycle helmet. According to the box, this spoiler provides additional down force at high speeds.

The spoiler: OKAY! OKAY! Quit yelling already!
(Click for larger image)

Another feature that stands out right away is the front chin vent. In fact there are three in total, but on the lower edge of the bottom front is a sizable vent that uses the RAM air principle to force air into the helmet. This venting system complements the already aggressive looking helmet. So, let's get to what this helmet is all about: venting.

To understand how the venting on the Domain functions, we’re going to have to give you a physics lesson. Otherwise, upon visual inspection only you may question the effectiveness of the venting.

Icon fitted what they call “supervents” to the top of the Domain helmet. These large channels do not function on the RAM air principle most are familiar with, but rather the Venturi effect. What’s that you say? The Venturi effect is variation of Bernoulli's principle. Fluid or airflow (in this case airflow) through a constricted channel (supervents) gains kinetic energy (energy of motion). The energy is supplied by a pressure gradient force from behind and results in high pressure flowing over the Domain’s vent holes.

Let’s use an analogy that most are familiar with to understand how the vents do their job: airplanes. The concept of lift is simple, create a high pressure area under the wing, a low(er) pressure area above the wing and you have lift. The top of an airplane wing is curved, leaving the air a longer path to travel as it’s disrupted over the wing. The underside if flat and smooth with no disruption creating lift. It’s almost as if the plane is vacuumed or pulled up by the high pressure air under the wing.

Now, reverse this scenario and flip it upside down. The supervents create a high pressure ABOVE the helmet in the supervent channels. The resulting low(er) pressure inside the helmet forces or sucks the air into the helmet. This doesn’t create lift on the helmet, but merely forces air into the helmet. The more airflow through the supervent channels, the more kinetic energy is gained and the end result: You stay cooler.

There are no fewer than nine total entry and exit ports on the Domain. It’s clear the engineering department at Icon wanted to make a statement when it came to venting.

Here you can see the underside of the supervents, holes in the styrene liner that let the air flow over your head.
(Click for larger image)

In our testing around town, we had better luck flipping the visor up a click or two for some relief. Since much of the ventilation relies on airflow, the stop and go and slow speeds around town left us longing for more air. With the molded breath deflector in place we were able to open the shield up to three notches and have no issues with wind in our eyes: contact lens wearers take note. The Domain does a fantastic job routing the air everywhere but right in your eyes.

At freeway speeds and during "spirited riding", the venting really had a chance to shine. At these speeds the visor must be kept down to avoid the wind catching it, but that’s fine because you don’t need the extra airflow. The effectiveness of the air is best appreciated after you’ve had a chance to sweat a little. In fact, you don’t realize how much air actually enters into the helmet until the perspiration on top of your head starts to evaporate.

On the inside you can see the adjustment for airflow into the chin vents.
(Click for larger image)

Icon has inserted a removable breath deflector into the Perimeter Domain. During the colder weather months, it serves as antifogging device. Along with the chin vent, both performed admirably in preventing fogging.

There’s no getting around it, if you want air, you get noise. Due to the extensive ventilation efforts and the application of the supervent channels, laminar airflow over the Domain is not as smooth as a standard spherical shape. Because of the disruptions in airflow and the generous venting, you will hear a lot of noise. In fact, this is the case with any helmet that aims to feature ventilation as a selling point.

First off, we should tell you that the Domain, at high speeds, is surprisingly stable in comparison with any helmet we’ve tested. Despite the external applications of the supervents, buffeting was not overly apparent during extending high speed riding. Icon must have spent some quality time in the wind tunnel developing this helmet. Otherwise, tack-on appliqués would create such a turbulent effect the effort would be exhausting. This is not the case with the Domain. Inserting the chin curtain seal further reduces the amount of buffeting you may experience.

While the lack of wind buffeting or wobble is very good, noise suppression may leave with you longing for ear plugs on long rides. Not unlike some of the other helmets we’ve tested the tradeoff for airflow comes in the form of noise. Whether you’re spending $200 on a helmet or $700 on a helmet, ventilation comes at a cost.

As with any helmet, proper sizing is very important. If your helmet is too tight, it will cause discomfort and you’re likely to either not wear it (gasp!) or wear something else. Too loose you’re subject to buffeting and lift from the wiggle room, not to mention the degraded safety effectiveness the helmet can offer in a crash.

The first step to ensure the helmet fits your properly is to measure your head. When measuring, wrap the tape around your forehead about an inch above your eyebrows and ears. You should take this measurement and compare it to a size chart to get an idea at what size you should start trying on helmets. What the chart shows and what you wind up with may not be the same size. Also, we prefer to measure in centimeters (cm), this will give you a more accurate measurement as the increments are smaller.

Armed with our handy measurement and Icon’s size chart we tried on several helmets. It’s important to note the brand new helmets you try on at your local dealer are going to be a little tighter that your purchased helmet will (eventually) become. Over time the lining will form to your face and expand. It’s better to choose something a little more snug than with a little room.

The sizing of the Icon helmet line is not much different from other helmets we’ve tested or tried on. Some products tend to “run large” or “run small”, we didn’t notice this with Icon’s sizing. And, while a small irritation, we wish the ear wells were slightly larger vertically. Maybe we have big ears, but it seemed like tight quarters for the ears.

If you do try on the Icon Perimeter Domain, it’s important to note that the cheek pads changeable and offered in varying thickness for a custom fit. The pads are also shaped a little differently than what you might find in other helmets. Icon states, “The cheek pads and liner are specially shaped to cup the rider’s jaw and cheek area reducing high speed wobble and creating a comfortable, secure fit…” We did notice a bit more pressure toward the front of the cheek pad; not an uncomfortable pressure but more of a reassuring snugness.

The liner: A comfortable interior awaits...
(Click for larger image)

Finally, Icon has designed the interior of the Perimeter Domain around an oval shape. Icon notes, “This ‘North American’ head form is far more comfortable than other helmets that press unduly on the forehead while not being secure on the sides of the head.” If you’ve got a round shaped head you will probably want to take advantage of the changeable pads.

Parts & Fit/Finish
We had no complaints with the fit and finish of our Perimeter Domain. The quality and craftsmanship were on par with other (more expensive) helmets that have come through our office. Most consumers expect high quality no matter when they’re shelling out for a helmet, and the Perimeter Domain does not disappoint. We struggled to find the smallest blemish and were unable to come with anything worthwhile mentioning.

As far as removable parts, as with most helmets on the market, the shield requires no tools to remove and liner is removable. Changing shields is a non-event and very similar to other mechanisms on the market.

On the Perimeter Domain, you simply raise the shield all the way and small plastic lever on either side to unlock/lock the “gearing” of the shield to/from the helmet. If there was one potential area of concern, this may be it.

Here is the ratcheting mechanism for the visor. You can see the plastic lever is currently in the OPEN position.

The resistance to lock the shield into place seemed high unless we applied a lot of pressure to the shield where is locks into place. The lever performing this function left us somewhat concerned that the amount of pressure require to actuate it might break it off; particularly if you don't press down on the shield. That said, we intentionally abused the mechanism by removing/replacing the shield and the levers held up admirably. And, since its plastic rubbing against plastic, it did become easier with each subsequent install. So, while the levers never failed, the first few times had us wincing and looking away hoping all would turn out well. It always did.

Replacement shields are only $25-$35, a bargain in our opinion. Our clear and mirror shield were both optically correct with no distortion or abnormalities. The seal around the shield to the helmet was tight all the way around. It integrates very well with the helmet.

The liner is well designed and also integrates very well with the helmet. Un-wedge a piece a here, unsnap a piece there and it’s out. It is easy to remove and almost appears as though it doesn’t remove; it’s so well incorporated into the overall design. Sometimes liners will have a tendency to partially remove themselves from a helmet after use, our liner managed to stay put during our testing.

As mentioned earlier, the supervents also do their job. The thought may cross your mind, “What if my Perimeter Domain falls from my bike and the supervents break?” Never fear, Icon offers the supervents as a customer-installed replaceable item. In fact, the supervents are designed to break upon impact (more on that below).

Icon has several safety features in the Perimeter Domain. First off, it is DOT and SNELL M2005 certified. It is the proprietary composite Icon chose to create the helmet that serves to certify the Perimeter Domain with these ratings.

The shell is created from what Icon calls a, “Carbon Fiber/Dyneema/Aramid Composite”. We are all familiar with Carbon Fiber and its characteristics. And you may or may not know, but Aramid is sometimes used synonymously with the brand name Kevlar©. Another name you might be familiar with is Dyneema.

Dyneema is a synthetic fiber composed of high molecular weight polyethelene (think Dacron). Dyneema is reportedly 40% stronger than Kevlar©, and like Kevlar© used in bullet-resistant vests. Dyneema is often used alongside Carbon Fiber to reinforce composites by adding stiffness. It is in the Perimeter Domain you find this application of Dyneema.

And, as an added benefit of using these high tech materials, the rider benefits from a considerably low-weight helmet. With our chin curtain seal removed (which only weighs a few ounces) our Perimeter Domain checked in at 53.347 ounces. We’ll do the math for you, that’s only 3.66 pounds!

As we mentioned earlier, the supervents are designed to break away on impact. Why would Icon do this? Safety. Because the supervents take away from the round shape of the shell, during a wreck the vents will break and fall away leaving you with a round-shaped helmet. End result: instead of your head getting caught on ground objects and bouncing, it slides instead, reducing the likelihood of head trauma.

The Perimeter Domain helmet is Icon’s newest top-of-the-line helmet. With a proprietary composite shell, excellent venting, eye-catching graphics and a price starting at about $340 (solid colors), you’ve got the whole package. Icon’s marketing has been aiming for the street rider and we think they found their mark with this helmet.

While there were small issues (ear-wells, shield mechanism lever) they should not detract from the total package. You may not experience a problem with either of these.

Here are a few of the flavors from which you may choose.

The Domain comes in solid colors including Black Gloss and Silver Gloss ($340) and Flat Black Rubatone ($350). The Domain also comes in the Perimeter graphic (Black, Silver, Blue, Red, Yellow) and sells for $360.

Comfort / Fit :

Coolness Factor:



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Copyright, 2006 ©The preceding article may not be reproduced in whole or part without express written consent of is in no way affiliated with Icon.
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