HEIDELBERG, Germany-- It’s made of plastic, foam and nylon, weighs in most cases less than a half-dozen eggs, and it can save your life. You wouldn’t dream of cruising the autobahn without your seatbelt, so why would you not wear a helmet when cycling?

Anyone here under the Status of Forces Agreement must wear a helmet while cycling, no matter if they’re going to the store for milk or whiling away the afternoon in the countryside.

From a strictly legal standpoint, Germans are not required to wear one while cycling, and many Americans find this disconcerting, because it seems, well, unfair. Shouldn’t we also be able to ride around with our hair whipping in the breeze like a shampoo commercial, swallowing bugs as we coast down a hill? Joking aside, there is a reason the government cramps your style: that little bit of synthetic materials can save your life.

No matter your cycling ability, you can count on crashing at least one point in your life. Maybe you have 22-year-old scars on your knees or maybe you just got a little scratched up. The point is, much like automobile accidents, you never know when one will occur.

Bicycle helmets are intended to take the impact and protect your noggin, and depending on the type of collision, are designed to separate down the middle like the hemispheres of your brain. If this makes you squeamish, imagine what could happen to you or your loved one if you don’t wear one, even that one time.

That means they also need to be worn correctly, which about 90 percent of children under 18 do not do. Simply put, if the helmet is uncomfortable or has to be pushed out of the eyes, it does not fit. Just grabbing the first helmet you see off the shelf and patting yourself on the back is not good enough. Fortunately, finding the right helmet is not rocket science.

Depending on the brand and style, helmets range in price from about $30 to a couple hundred. For commuters, road and mountain bikers, skateboarders and inline skaters, sport helmets are probably sufficient and are the least pricy. Generally, the lighter the helmet, the more it costs.

For the size, wrap a tape measure around the biggest part of the head. Most helmets are either universally sized or come in extra small (under 20 inches), small (20 inches), medium (21.75 inches), large (23.25 inches) and extra large (24.75), but always double check with the manufacturer. Those between sizes should choose the smaller.

Almost all helmets have one size fits all rings and adjustable straps, and some kids’ helmets include spare pads to help with fit. A well-fitting helmet should be snug but never tight and should sit level on your head with the front edge no more than an inch above the eyebrows (probably where you measured) so the forehead is also protected.

Once on, push the helmet from all directions, shake your head, do a little dance. If it shifts, adjust the sizing ring or pads and tighten and close the chinstraps. Yawn, yell and move your jaw around, maybe sing a tune. If the chin strap moves away, try again.

Now you’re ready to take off. See you on the road.