E-bike head injuries increase 49x in five years, US study shows

A new study in the US shows that e-bike head injuries are rising much faster than e-bike imports. All the while, helmet use is dropping by 5.6% a year

12:30, Monday 26th February 2024

James Howell-Jones

Junior Writer

E-bike head injuries have increased 49x since 2017

A new study of US hospital data has revealed that e-bikes are involved in thousands of head injuries a year, with injury rates increasing disproportionately compared with the number of e-bikes imported into the country.

The study also revealed that only 44% of the hospitalised e-bike riders were wearing helmets, and that riders without a helmet were almost twice as likely to suffer head injuries than ones wearing a helmet.

Since the study only considered emergency room data, the findings have their limitations. Even so, the dramatic increase in head injuries suggests that e-bikes pose a greater risk to cyclists than normal bikes.

The authors say that these findings should prompt more investigations to work out what makes e-bikes unsafe. It seems likely the higher power and speed limits for e-bikes in the USA compared with the UK, Europe and most of Australia have a part to play.

How the study worked

The survey used data from 2017 to 2022 from the National Electronic Injury Surveillance System (NEISS), which provides estimates of patients at US emergency departments. By querying the data for e-bike related terms, the researchers isolated e-bike injuries from normal bicycle injuries, and from injuries caused by similar devices such as mopeds or e-scooters.

By examining a sample of 1,038 NEISS cases, they compared the head injury statistics for e-bikes versus normal bikes, and compared riders who were wearing a helmet and those who weren't.

Read more: 10 benefits of riding an e-bike

The findings: e-bikes lead to a greater rate of injury

Between 2017 and 2022, there were an estimated 45,586 e-bike injuries in the US, 5,462 of which led to hospitalisation. In those five years, the rate of e-bike injuries increased 30x, and the rate of hospitalisation increased 43x.

The increase was even more pronounced with head injuries. There were 49 times more head injuries in 2022 than 2017 – 7,922 compared with 163. Given that head injury rates are higher than other injury rates, this leads the authors of the study to suggest that e-bikes pose a more pronounced risk of head injuries.

Something that the authors don't account for in the summary of their findings is the fact that e-bikes have become significantly more popular between 2017 and 2022, so it is natural that the rate of injury will increase as more people ride e-bikes.

However, the rate of injuries has increased far more than the popularity of e-bikes. In 2017, best estimates suggest that 260,000 e-bikes were imported into the USA. In 2022, imports were at 1.1 million, meaning that if injuries had risen proportionally, we would have seen about 4x more e-bike injuries in 2022 than 2017.

Most injured riders weren't wearing helmets

Most of the hospitalised e-bike riders were not wearing helmets. Only 44% of injured riders were wearing helmets, and the authors conclude that e-bike riders who went without a helmet were 1.9x more likely to sustain a head injury.

In reality, this figure is probably too low; this study only looks at riders who were logged by the emergency department, so there is no way of knowing how many unreported crashes took place in which a helmet prevents a head injury.

The study's senior author Dr. Benjamin Breyer from the University of California, San Francisco, told NPR he hoped the study would encourage helmet usage, not decrease e-bike usage:

"I'd love to see more people wearing helmets. And I really do think that as a society, cities and towns can produce real changes on the road that impact safety and prevent these kinds of injuries."

Read more: How to spot an illegal e-bike

Are e-bikes unsafe?

The report suggests that traumatic brain injuries are more severe in e-bike incidents, compared to normal bikes, which is hardly surprising given the higher speeds that riders can hit on an e-bike. In the USA, the speed limit for e-bike motor assistance is 20mph (32kph), much higher than the 15.5mph (25kph) limit in Europe and most of Australia.

As the researchers conclude, these findings are a prompt for further investigation into the safety profiles of e-bikes. Regulation speeds and power limits vary around the world, and the United States has a higher speed and power limit than many other countries — e-bikes in America can have up to 750W of output power, compared to just 250W in Europe and most of Australia.

E-bikes are growing in popularity, and that is a good thing. E-bikes reduce pollution and congestion, and they make people more active by replacing a car for shorter journeys. However, those benefits need to be balanced with the risk factor.

With regulation varying around the world, it's hard to see the different limitations on e-bikes as anything other than 'finger in the air' logic from legislators, rushing to control this new technology. More work is needed to understand the point at which e-bikes become unsafe, and to adjust the rules accordingly.