Children make up a disproportionate number of those injured in cycling accidents -- about one third of all serious brain injuries. A good bike helmet --correctly fitted can reduce the risk.

The right helmet with the right fit can make cycling safer and more enjoyable, How to choose the best one for your kids

Pediatric neurosurgeon Michael Tobias wants kids to wear a bike helmet. He's seen the dire consequences of not wearing one.

"I rarely meet kids that were wearing their bicycle helmets. I usually meet kids that weren't wearing their helmets, or weren't wearing their helmets properly," he said.

Consumer Reports put a dozen children's bike helmets through some tough tests to see how well they'd protect your child.

In all, Consumer Reports tested a dozen helmets, ranging in price from $18 to $50.

One test simulates what happens when your head hits the pavement. Not pretty.

Another test applies sudden force to the helmets straps and buckle to see whether they stretch or break. That helps determine whether the helmet would come off in an accident.

Consumer Reports says it doesn't matter whether you get a good helmet if it doesn't fit correctly.

A popular Hannah Montana denim helmet is supposed to fit children eight and up. But Consumer Reports found it is too big for some eight-year-olds. It actually fit some adults!

"A good-fitting helmet should fit snugly even before you tighten the straps," Consumer Reports Rich Handel said.

It should also be level and no more than one or two fingers widths above the brow. The straps should form a v under each ear and the buckle should be centered under the chin.

The bell amigo bicycle helmet for $38 rated excellent for ease of use

Over time, a bicycle helmets straps may need to be adjusted either because of stretching, slippage, or a child's growth. So make sure you check them periodically.

As a rule of thumb, you should replace a helmet at least every five years, And be sure to get a new helmet after an accident. They are good for one accident only -- even if they don't looked damaged.

With a report from CTV British Columbia's Chris Olsen