Fitting the Helmet to Your Head
Now that we've got an idea about how hard of a helmet we're most comfortable with, and which helmets fit that need, it's time think about fitting a helmet to a head. How a helmet fits is important for a couple of reasons. Since we'll likely be wearing it for an hour or more at least occasionally, comfort is important. It's no fun to have helmet liner scrubbing skin off your forehead while you're cruising down the road. Also, the protection that a helmet can give your brain is lessened if our head is rattling around inside it.
The idea is to find a helmet that fits your head with an even snugness, one with no "hotspots." A hotspot is a place on your head where the helmet is to tight and will become uncomfortable after a while. If a helmet you're considering is too tight in one place, it does not fit your head correctly and will likely be too loose in another place. The thing to do is to try on helmets from various manufacturers. Each one is designed with a different head shape in mind. Some are more round, some are more oval. When you've tried on enough helmets from enough makers to have found which one's fit you best, it's time to get the size right.
Arm yourself with two pieces of information before starting serious helmet shopping; your hat size and your head measurement. If you do not already know your hat size, find a hat that fits and look at the tag. Enough said about that. To get your head measurement, use a cloth tape if at all possible. It will conform to your head better than other types of tape measures. Starting about one inch above your eyebrows, wrap the tape around the largest part of your head above the base of your skull until you've found the largest possible measurement. These two sizing methods will be starting points for getting the right size.
Most helmets will have one or both of these measurements on a tag inside the helmet. If your exact measurement falls in between your manufacturers sizes, try both the larger and smaller sizes on. While the helmet is on your head, make sure of a couple of fit points. The cheek pads should touch your cheeks while putting minimal pressure on them. Use a finger to check for gaps between you and the helmet lining. Gaps are bad. For maximum protection, your skull and the liner should be in contact. If you try different sizes and still have gaps, try different manufacturers again.
With the helmet on and the chin strap off, grab the helmet with your hands and rotate it front to back and side to side on your head. Notice whether the helmet's movement causes your skin to move. Also note skin movement while lifting the helmet up off of your head. If these actions do not cause skin movement, the helmet is too large. If skin does move, the next step is to buckle the chin strap, grab the back of the helmet at the neck and try to pull it up and over your head. If you can, the helmet is definitely too big. If you're buying a full face helmet, lower the face shield and push the front of the helmet back towards your face. The shield should not make contact with your nose.
Once a helmet has passed all these tests and exerts a comfortable, even pressure around your head, you have the right brand and size that will work best for you. Now all you have to think about is ventilation. If you live in a colder climate, ventilation might be a bigger consideration as more air flow through the helmet may keep fogging to a minimum. In hotter climates, ventilation may also be a bigger concern. For me personally, I can not really tell the difference between riding with vents open or closed. Some people say they can. There may also be a correlation between huge vents and wind noise but again, it's nothing I notice. In my opinion, ventilation is purely a personal preference.
Now just choose the color and style that makes you happiest, get yourself in the wind and have some fun.