A bicycle helmet can reduce the risk of head injuries by 85%, but only if it fits properly and is fastened correctly. Start with a helmet that’s the right size. It needs to be snug, but not too tight. Unlike clothing, don’t buy a helmet a size too big for your child to grow into. Use the small foam pads that come with the helmet to adjust the fit so it’s comfortable. Now make sure it’s level at the front and the back and then adjust the straps so it stays that way when it’s done up. That’s the only way of protecting critical areas of the brain. Check also to make sure that the helmet doesn’t slip from side to side. The straps should meet just under the ear. And while the straps need to be roomy enough to allow your child to open her mouth, they must never be loose. Your child shouldn’t wear anything under their helmet. It’s designed to provide the most effective protection when worn directly on the head. If you’re concerned about the cold, winter helmets are also available.