Despite some criticism of bike helmets for not being protective enough, they do cut the risk of severe traumatic brain injury (TBI) by half when riders suffer a head injury, a U.S. study suggests.

Riders with helmets were also less likely to die from their injuries, and less likely to break facial bones, than those not wearing a helmet, researchers report in American Journal of Surgery.

Researchers found that people wearing helmets had 52% lower risk of severe TBI, compared to unhelmeted riders, and a 44% lower risk of death.

Riders with helmets also had 31% lower odds of facial fractures. The upper part of the face, particularly around the eyes, was most protected. Helmets offered less protection against fractures to the lower part of the face, such as the nose and jaw.

Moreover, people who wore helmets reduced their likelihood of having brain surgery, further confirming a certain level of protection with helmet use, the study team writes.