What Percentage of Bike Crashes Result in Head Injury?

About one-third of bicycle injuries treated in emergency rooms involve the head, and head injuries cause roughly 60% of cyclist deaths. The exact figure depends on whether a study counts all bike crashes, hospital visits, or fatalities. Helmets cut head injury risk by about half.

How Common Are Head Injuries in Bike Crashes?

Head injuries occur in about one in three non-fatal bike crashes that reach an emergency room and in most fatal ones. Newer data puts the non-fatal rate somewhat lower.

The National Safety Council recorded 454,008 bicycle-related ER visits in 2024. IIHS reports 1,075 cyclists killed that same year.

Why Head Injury Statistics Vary

Studies count different groups of riders, such as those in bike crashes resulting in an ER visit or a death, and define “head injury” differently. Fatal crash studies produce high percentages because head trauma is the leading cause of death in fatal bicycle accidents. ER records produce lower numbers because most riders survive with injuries to other parts of the body.

Definitions matter too, since the CDC counts only concussions and other traumatic brain injuries, while broader studies include scalp and facial cuts. Much of the “one-third” figure still cited today comes from a single study using data from the 1980s.

Types of Head Injuries in Bike Crashes

Concussions are the most common brain injury in bike crashes. The main types of bicycle accident head injuries include:

• Concussion. Headaches, dizziness, nausea, and trouble concentrating often appear hours or days after the crash. CT scans usually do not show them.
• Skull fracture. A break in the skull from a direct impact, often with swelling, confusion, or loss of consciousness. Helmets protect best against this injury.
• Cerebral contusion. Bruising of brain tissue, usually from the head hitting the road or a vehicle. Severe cases may need surgery to relieve pressure.
• Diffuse axonal injury. Tearing of nerve fibers when the brain twists inside the skull. It is the least common and most serious type, and survivors often need lifelong care.

Other Common Bike Accident Injuries

Riders who hit the ground often injure several parts of the body at once. Common bicycle accident injuries include:

Riders who hit the ground often injure several parts of the body at once. Common bicycle accident injuries include:

• Facial fractures and dental injuries
• Broken collarbones, wrists, and arms
• Road rash and deep lacerations
• Neck and spinal cord injuries
• Internal injuries from vehicle impact

Do Helmets Prevent Head Injuries?

Helmets reduce head injury risk by 48% and TBI risk by 53%, based on a 2018 review of 55 studies. They do not reliably prevent concussions.

The 85% and 88% figures found on many websites come from a 1989 Seattle study. Its authors later revised the estimate to 69%, and NHTSA and the CDC stopped citing the original numbers in 2013.

Who Is Most at Risk?

Adult riders in cities face the highest risk of a fatal head injury. According to IIHS data for 2024:

• 89% of cyclists killed were age 20 or older.
• 81% of deaths happened in urban areas.
• 68% of those killed were not wearing a helmet.
• Deaths peaked between 6 p.m. and 9 p.m.
• 18% of riders 16 and older who died had a blood alcohol level at or above the legal driving limit.

NHTSA found that 28% of cyclist deaths in 2023 happened at intersections and about half occurred after dark. Cyclist deaths have risen 73% since 2010, almost entirely among adults, even as the injury rate per rider has dropped.

Long-Term Effects of a Bike Accident Head Injury

Most riders with head trauma are treated and released from the ER, but about 14% are hospitalized or transferred. Recovery costs often go well beyond the initial medical bills.

Long-term costs can include:

• Physical therapy and cognitive rehabilitation
• Specialist visits and follow-up imaging
• Lost wages or reduced earning capacity
• In-home care from a family member

Memory problems, anxiety, trouble focusing, and mood changes can last for months after a scan looks normal.

Can You Get Compensation If You Weren’t Wearing a Helmet in Arizona?

You can still recover compensation in Arizona if you were not wearing a helmet. Arizona has no statewide bicycle helmet law for adults, so riding without one is not a violation.

An insurance company may argue that a helmet would have reduced your injuries and should lower your settlement. To make that argument work, it has to show the missing helmet caused or worsened the specific harm you are claiming. That is hard to prove for concussions, and it does not apply to injuries such as a broken arm or collarbone.

Arizona follows a pure comparative fault rule (A.R.S. 12-2505). Even if some fault is assigned to you, your compensation is reduced by your share, not eliminated. You generally have two years from the crash to file a personal injury lawsuit in Arizona.

What to Do After a Head Injury in a Bike Crash

Seek medical attention within 24 hours, even if you feel fine. Prompt medical care matters because symptoms often appear days later, and insurers use gaps in treatment to dispute personal injury claims.

1. Stay still and check for symptoms. Look for dizziness, confusion, nausea, or trouble focusing before standing up.
2. Call 911. Paramedics can spot signs you might miss, and the police report documents the crash.
3. Take photos. Photograph the scene, your bike, your injuries, and your helmet. Keep the helmet, since damage shows where the impact landed.
4. Tell the doctor you hit your head. A clear CT scan rules out bleeding, not a concussion.
5. Track your symptoms daily. Note headaches, sleep problems, memory issues, and mood changes as they happen.

Talk to a Bicycle Accident Lawyer

If a driver caused your crash, a bicycle accident attorney can handle the insurance company while you focus on recovery. We review medical records, gather evidence of liability, and calculate the full cost of your injury, including future care. If a crash was fatal, our team can help surviving family members understand their legal options, including a wrongful death claim.

Bicycle Accident Lawyers Group offers a free consultation, and you pay no fees unless we win. Call (888) 521-6377 or contact us online to discuss your case with a personal injury lawyer.

Posted by Robert Goldwater

Robert Goldwater is a cyclist representing cyclists. He has practiced personal injury and wrongful death law for more than 20 years, graduating with Honors from Arizona State University Law School, and has helped recover over $1 billion for clients, including injured cyclists.

All articles by Robert Goldwater