No matter what you ride, where you ride, or why you ride, the bicycle helmet is your last line of defense in an accident.  A helmet will not protect your head if it is not properly fit. So let’s get a fresh start on how to properly fit the bicycle helmet with some help from the Bicycle Helmet Safety Institute.

Helmets that fit with pads come with at least one set of foam fitting pads, and if you got a second set of thicker pads it can be used to customize the shape. For starters, you can often remove the top pad entirely or use the thinnest ones. This lowers the helmet on the head, bringing its protection down further on the sides. It may reduce the flow of cooling air slightly, but probably not enough to notice

Adjust the side fit pads by using thicker pads if your head is narrow and there is a space, or add thicker pads in the back for shorter heads. You may also move pads around, particularly on the "corners" in the front and rear. Leaving some gaps will improve air flow. The pads should touch your head evenly all the way around, without making the fit too tight. The pads may compress slightly over time, but not much, so do not count on that to loosen the fit. The helmet should sit level on the head, with the front just above the eyebrows, or if the rider uses glasses, just above the frame of the glasses. If you walk into a wall, the helmet should hit before your nose does.

There are also helmets on the market that use a fitting ring rather than side pads for adjustment. With these one-size-fits-all models you begin by adjusting the size of the ring. Some of them may require the ring so tight for real stability on your head that they feel binding, but loosening the ring can produce a sloppy fit, indicating that the helmet is not for you.

Now put the helmet on and fasten the buckle. Be sure the front is in front! You want to adjust it to the "Eye-Ear-Mouth" test developed by the Bicycle Coalition of Maine:

• When you look upward the front rim should be barely visible to your eye
• The Y of the side straps should meet just below your ear
• The chin strap should be snug against the chin so that when you open your mouth very wide you feel the helmet pull down a little bit.

With the helmet in position on your head, adjust the length of the rear straps, then the length of the front straps, to locate the Y fitting where the straps come together just under your ear. That may involve sliding the straps across the top of the helmet to get the length even on both sides. Then adjust the length of the chin strap so it is comfortably snug. If it cuts into the chin and is not comfortable, it is too tight. When you think the straps are about right, shake your head around violently. Then put your palm under the front edge and push up and back. Can you move the helmet more than an inch or so from level, exposing your bare forehead? Then you need to tighten the strap in front of your ear, and perhaps loosen the rear strap behind your ear. Again, the two straps should meet just below your ear. Now reach back and grab the back edge. Pull up. Can you move the helmet more than an inch? If so, tighten the rear strap.

When you are done, your helmet should be level, feel solid on your head and be comfortable. It should not bump on your glasses (if it does, tighten the nape strap). It should pass the eye-ear-mouth test. You should forget you are wearing it most of the time, just like a seat belt or a good pair of shoes. If it still does not fit that way, keep working with the straps and pads, or try another helmet.

After a crash or impact on your helmet, replace it immediately