I was curious if bike helmets protect bicycle riders from injuries to the head, and the answer in the epidemiology literature is “yes.” If that is all you are interested in, then read no further. Jk. Actually the topic is quite nuanced and has a lot of different interest groups besides just cyclists- groups like helmet companies, government, and public health researchers and clinicians.
One thing I found is that more studies on bike injuries are needed. It appears that the critical question of helmet vs. no helmet has been answered, but big gaps in research still remain about the safety of specific helmet designs (shape, fitted vs. ill fitted, specific materials and failure rates), differences in driver behavior towards helmet wearers, the psychology of wearing a helmet, and policy decisions about legislated vs. non-legesated helmet use. Even simple surveys of helmet use are lacking. Many times helmet data is not collected after traffic accidents- such as NYC with “only 1/3 of 1037 serious injury crashes from 2001-2003 was helmet use recorded” (pdf).
Do helmets work?
It is known with some confidence that helmet use greatly reduces the risk of bicycle-related head injuries
- by 63-88% for head, brain, and severe brain injury among cyclists of all ages in a meta analysis of 5 studies (article; criticism and rebuttal of the article).
- by 65 % to the nose and upper face but not the lower face (article)
What is the risk of injury?
One study estimated that children <17 iu urban areas have serious bike related accidents at a rate of 37.4 in 100,000 (article). I could not find a rate for adults or all riders.
What are risk factors for bicycle injuries (article):
- Cyclist is male.
- Cyclist is nine to 14 years of age.
- Cycling in the summer.
- Cycling in late afternoon or early evening.
- Cyclist does not wear helmet.
- Motor vehicle involved.
- Unsafe riding environment.
- Cyclist is from an unstable family environment.
- Cyclist has preexisting psychiatric condition.
- Cyclist is intoxicated.
- Cyclist is involved in competitive mountain-bike racing.
I have a few risks to add myself:
- talking on a cellphone (driver or biker)
- near an intersection
- deaths by collision with a large vehicle
- helmet type/shape (data not collected on round vs. aerodynamic helmets, but there is research that shows that aero helmets cause more neck strain in sideways/rolling falls)
- helmet fit (article)
- defective or not maintained parts. I see people all the time with dangerously bad breaks and handlebars. Either by ignorance or laziness these problems persist. One way to tell is somebody’s bike is not in good shape is to look for little things that are not dangerous problems, like unraveling handlebar tape, but could indicate general neglect.
- on an arterial street or highway
Are you still not convinced?
Bicycle helmet companies and bike activists won’t say this, but if you absolutely don’t want to wear a helmet there are other ways to reduce your risk of major injuries while riding. These involve reducing other risks associated with injuries, such as from the list above. Best best are to ride on secondary roads with slow traffic, good lighting, few intersections, and wide lanes. Ride with a friend to be more visible and better at clogging up the right lane. Another speculative idea is to bike with a mild wobble to cause cars to give a wide berth.