In examining our plethora of motorcycle helmets, we were quite surprised at the quality of some of the midrange and economy models. You shouldn't discount some of the lesser brands just because they are not mainstream brands. Check out Art & Science for a more detailed discussion of helmet technology, but essentially you should know that your helmet needs to meet DOT or some other recognized standard to assure a decent level of protection. DOT-approved helmets will have a sticker on the outside along with a warning label inside. Check under the comfort lining for a Snell approval sticker. Neither standard requires that the EPS (expanded polystyrene) liner extends around the chin bar and into the cheek pads, but some models will offer this extra protection. Check by pressing the inside of the chin bar with your finger; EPS will deform permanently, plain padding will spring back.
The warning label inside will detail the materials used in the helmet's shell and liner. Shell material can be divided into two categories: thermoplastic and composite. In general, thermoplastic shells are easier to manufacture, making the helmet less expensive, but a composite helmet will be somewhat lighter. Protection-wise, motorcycle helmets made with either material are capable of meeting Snell and DOT requirements.
Most importantly, from both a safety and comfort standpoint, a helmet must fit you properly. It should be snug on the top and sides of your head, around your ears and the sides of your jaw. There should not be any pressure points where you feel the interior comfort lining bottomed out against the EPS liner. To see if the lid is too loose, hold your head steady while trying to move the helmet side-to-side. The helmet should not slide anywhere on your head, but rather you should feel your skin being pulled with the helmet. Try one size smaller if you are uncertain. If you need to wear glasses while riding, bring them along to make sure you can fit them in the helmet.
If a particular helmet doesn't fit right, don't automatically dismiss that brand as being unsuitable. Different models from the same company have different shapes, and another model may fit you fine. Keep trying different styles, and decide on a few that have an acceptable fit. While it's an unlikely occurrence, make sure that you can't rotate the lid off the front of your head with the strap still buckled.
Check the face shield for gaps between it and the molding by looking parallel to the shield. Any gaps will let the breeze in, as well as adding extra wind noise. Some helmets have an adjustment in the sideplate to deal with this. While you're eyeing the opening mechanism, see how difficult it is to change the shield-some are simple, some are next to impossible.
Don the helmet and close the face shield. Check that you have plenty of peripheral vision and that the chin bar will not obstruct your view of the instruments. Move your head side-to-side and up-and-down, while eyeing something with straight lines. The lines should stay straight, and not go wavy with the movement of the shield-be sure to check out the sides, where waviness can give you false impressions in your peripheral vision.
If you don't like to wear sunglasses while riding, find out what optional shields fit the helmet you are considering. Most helmets come standard with a clear shield, but a dark or smoked visor will allow you to ride during the day without sacrificing your peripheral vision by using sunglasses. Lightly smoked shields are handy for those winter days, when you ride to work in daylight and home in the dark, but don't want to change shields twice a day. And the fancy orange shields you see are used in cloudy or rainy conditions for high-definition.
More motorcycle helmet manufacturers are employing removable liners that can be washed and cheek pads that can be replaced when worn-out. One advantage of this is the opportunity to tailor a particular helmet to your head by mixing and matching the interior components. Most manufacturers offer the liners and pads separately, and if your heart is set on a particular brand or model, a good dealer will let you sample different combinations. Once you've narrowed the field down to a few potentials that fit you well, start looking at the details.
You'll welcome some venting in hot weather, and this is one area where the higher-end helmets excel. Make sure that those fancy scoops are in fact vents to the inside of the helmet and you can open and close them easily--with gloves on. Ideally, there will be a way for air to get into the helmet (at the front) and a way for that air to get out (at the back).
Pay attention to how the strap feels and whether or not it has its own padding. There also should be a snap or some method of stopping the loose end from slapping around in the breeze.
OK, so you have a lid that fits well, has a good face shield and venting, and is nice and comfy. Now, see if the kind person behind the counter will let you take it for a test ride. That's the only true way to see if the venting, sound and vision are acceptable. Or, try and work some kind of deal where you can return the helmet after a day or so if you are not happy with it. Remember, you'll have to live up close and personal with whatever helmet you buy, so it's worth making sure what you end up with is the best you can afford.