(CBS) — Most of us would never let a child ride a bike without a helmet. Yet more adults are skipping this important safety step, and the consequence can be grim.

CBS 2’s Roseanne Tellez reports.

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Helmets can reduce the risk of head injury by as much as 87 percent. But not everyone wears one.

A new study found in cities like Chicago with bike-sharing programs, head injuries from bike accidents increased 8 percent.

John Hruska, 58, spent two months in the hospital, temporarily paralyzed after he bumped a curb on his bike, lost a tire and flipped.

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“I looked like I had been dragged behind a truck,” he says of his injuries.

Dr. James Doherty is one of a group of trauma surgeons at Advocate Christ Medical Center calling on cyclists to wear helmets. He hopes bike-sharing programs would provide them.

“The addition of a helmet can protect your brain significantly from injury,” he says. “I understand why people make that choice, but i think it’s a bad choice. If you should do it for your child, you should do it for yourself.”

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Divvy representatives say they are exploring options for people to rent helmets for Chicago’s bike-sharing program. There’s no law requiring them.