Electric Bikes Are Emerging as Public Health Hazard

The worldwide sales and use of electric bicycles (e-bikes) have grown dramatically in the past decade, particularly among children and adolescents, becoming an increasing source of road traffic-related morbidity and mortality. Surgeons around the world have witnessed a serious pattern of e-bike-related injury and death.

E-bikes are regulated quite differently around the world, and laws governing their use vary by individual states in the US. In some municipalities, they are banned; elsewhere, they are regulated as either bicycles, mopeds, motorcycles, or as motorized vehicles.

History

The first patents for battery-powered bicycles were issued in France and the US in the late 19th century.¹ The French model used a lever system to power the bike rather than a pedal, and the original designs used batteries of lower efficiency compared to today.  

The major advancement in the 20th century was the introduction of a pedal-assisted bicycle, also known as a pedelec—a low-powered e-bike that combines the rider’s pedaling and an electric motor. An electronic controller cuts power to the motor either when the rider is not pedaling, or when a certain speed (approximately 20 mph) is reached. Many jurisdictions classify pedelecs as bicycles rather than mopeds or motorcycles. 

In 2024, there has been a rapidly growing combination of pedal-assist and throttle-style e-bikes, with a wide range of designs. Some more powerful e-bikes (Class 2) provide assistance regardless of whether the rider is pedaling and can be accelerated by throttle alone, thus more closely resembling mopeds. Another concern is that some controllers can be deactivated by a magnet or a series of keystrokes allowing speeds greater than 37 mph, which are comparable to motorcycles.

Advantages of E-Bikes

Due to the increased speeds, e-bikes make it possible to commute longer distances in shorter time, as they quickly achieve relatively high speeds with minimal physical effort. E-bikes are particularly helpful when riding up hills or into strong headwinds.

E-bikes may represent an economical, environmentally friendly, and more sustainable mode of transportation that reduces greenhouse gas emissions compared to a car, and rising gasoline prices further increase the value of e-bikes. 

Disadvantages of E-Bikes

The higher e-bike speeds reduce reaction time for riders to avoid potential collisions. Attractive styling, naming, and bicycle-like appearance may not convey these risks to younger riders or parents. Special caution should be exercised in traffic and when traveling downhill, as the heavier battery can lead to faster acceleration and loss of control.  

Definition of an E-Bike, Classification in the US

E-bikes are part of a growing class of devices known as electric mobility devices, which include e-scooters, e-unicycles, e-skateboards, e-hoverboards, and the balance scooter Segway. The basic components of an e-bike are a battery, controller, and motor. Accessory components include the displays, throttles, and sensors.

US federal regulations limit e-bikes to a motor with a power rating of less than 750 watts and require fully operable pedals.² Several nations set lower power limits ranging from 200 to 500 watts. However, conversion kits available online can alter many e-bikes by 1,000 watts or more to high-power models, thereby evading initial sale labeling requirements. These conversion kits are banned in some locations (i.e., the UK). 

A major challenge for policymakers is the lack of a consistent classification around the nation or globe, with US state laws varying widely and sometimes in conflict. In some municipalities (i.e., Hong Kong) and colleges (i.e., some California state universities), e-bikes have been banned. Many nations restrict use to those who are 16 years and older. In Hawaii, registered e-bike owners must be 18 years old with a minimum age of 15 to operate an e-bike. 

Regulations for helmet use also vary widely with some states not specifying any helmet requirements for e-bike use. The variation in laws helps explain why the observed severity of injury differs across the US. 

In the US, manufacturers currently classify e-bikes in three categories (see Table 1).

• Class 1: A pedal-assist e-bike equipped with a motor that provides assistance only when the rider is pedaling and ceases to provide assistance when the bicycle reaches 20 mph
• Class 2: Equipped with a motor that can be used exclusively to propel the bicycle with the use of a throttle, which also has a maximum speed of 20 mph
• Class 3: A pedal-assist e-bike equipped with a motor that provides assistance only when the rider is pedaling and ceases to provide assistance when the bicycle reaches 28 mph

California law requires manufacturers and distributors to permanently affix a label to each e-bike that includes the classification number, top speed, and motor wattage. Most e-bikes are manufactured overseas, and an estimated 990,000 were imported into the US in 2023, comparable to the 800,000 electric cars sold in 2022. In California, rebate programs seek to increase e-bike adoption to replace car usage.

The US Consumer Product Safety Commission (CPSC) recommends that children under age 12 should not operate any e-bike that travels more than 10 mph. The risk to children operating faster devices is acknowledged by many states that prohibit Class 3 e-bike operation by anyone younger than 16. 

In 2023, the CPSC issued a statement highlighting that the existing classification is not part of its statutes.³ To address the injuries and death occurring nationally, in spring 2024, the CPSC issued a call for public comment about rulemaking related to e-bike safety in the US. 

Worldwide Experience

The modern evolution of e-bikes began in Asia and were initially met with limited enthusiasm. Europe was the next early adopter, and numerous scientific articles described the novel e-bike dangers and risk of severe injuries (neurosurgical, orthopaedic, and maxillofacial), sometimes resulting from the poorly developed batteries. With increasing modifications and safety features, e-bikes gained increasing popularity, especially in Asia, which hosts the largest number of e-bikes worldwide.

A worldwide review revealed several countries have implemented policies and laws in response to studies of injuries, especially in children. Laws regulating the limits of wattage, age, and areas of operation have been implemented. Notably, there is no unified legislation regarding e-bike power or speed limitations, and inadequate regulation likely contributes to the greater injury severity seen in e-bike riders compared to nonmotorized bicycles.

A 2017 study of 549 Israeli patients after e-bike crashes noted 65% suffered orthopaedic injuries.⁴ E-bike riders are more likely to sustain fatal injuries after collision with a motor vehicle, which can partially be attributed to e-bike riders frequently sharing the road with cars and not using dedicated bicycle lanes. 

Pediatric populations appear to be particularly susceptible to serious injury, with a recent review noting 35% of all e-bike-related trauma occurs in patients under 18. A study of 561 Israeli pediatric patients noted higher rates of accidents involving motorized vehicles and greater incidence of head injuries, lower extremity trauma, and need for orthopaedic operations in the e-bike cohort, compared to conventional bicycles.⁵ The greater proportion of head and neck injuries may be attributable to the larger head-to-body size and weight ratio in children.

A 2018 Dutch Level I trauma study of the 10-year history of bicycle accidents at their institution noted that e-bikes accounted for 2.9% of their accidents but represented 27.6% of the fatal bicycle accidents nationwide in 2017.⁶ The Netherlands set the limit for e-bikes to 15 mph (routinely verified by police inspection) and set the minimum age of ownership to 16.

US Experience

The US has seen two eras in e-bike injury—an early era with the majority of deaths in older patients who have the financial resources to purchase earlier generation and more expensive e-bikes but were less skilled riding a bicycle. During the pandemic, sales of all bikes increased, and the closure of gyms and social distancing led some to purchase e-bikes as a safe option for outdoor exercise. In the second era, e-bike prices fell significantly and became more affordable, leading to a dramatic increase in pediatric use and injury.

Marin County, California

Marin is recognized as the birthplace of the modern mountain biking industry. For decades, MarinHealth Medical Center has been the primary hospital treating bicyclists injured across the county. In 2023, Marin surgeons began reporting the new hazards with e-bikes.

An analysis of the MarinHealth Medical Center trauma registry revealed that e-bike accident victims compared to regular bicyclists were nearly a decade older in age, more likely to require hospital admission, and had a higher risk of dying (more than 10% of e-bike riders who crash and then present to the trauma center expired).⁷ The e-bike injury pattern includes pelvic fractures, which are more commonly seen in motorcycle riders than bicyclists.

San Diego

A retrospective study of trauma center registries from one pediatric and five adult trauma centers in San Diego County were matched with collisions documented in the Statewide Integrated Traffic Records System (SWITRS) from 2018 to 2023. E-bike injuries increased between 2018–2023 (see Figure 1).

In San Diego, the most common traffic violation (see Table 2) for bicyclists was improper turns, but for e-bike riders, it was unsafe speed (18.6% versus 10.9%, p < 0.001). Compared to bicycle injuries, injured e-bike riders are younger, more likely female, and their accidents occur in areas of higher socioeconomic status. Injury severity is higher in e-bike injuries, reflecting the injury mechanism.

California

A retrospective analysis of the SWITRS 2018–2023 database of e-bike injury collisions showed that e-bike incidents increased 18.6-fold over 5 years—from 184 to 3,429 events, rising from 1.5% to 4.9% of bicycle group accidents (see Figure 2). Mean SWITRS injury severity category of e-bike injuries was higher than bicycles (1.94 ± 0.16 versus 1.74 ± 0.16, p < 0.001).

National

According to the New York City Department of Transportation, bicycle deaths reached a 24-year high in New York City in 2023, as 30 people were killed on a bicycle, 23 of whom were riding e-bikes.⁸ Three pedestrians also were killed by e-bike riders. Increased delivery services by e-bike, bidirectional bicycle lanes, riding in traffic, and a proliferation of e-bike city rentals have contributed to the increased injuries.

In February 2024, US researchers reported a dramatic 49-fold increase in e-bike riders with head trauma nationally over the past 5 years, which they attribute to a lack of safety regulations like mandatory helmets, speed limits for e-bikes, and age restrictions.⁹

Across the US, lithium-ion battery explosions in e-bikes leading to fires have been reported. In 2023, 267 fires caused by lithium-ion batteries injured 150 and led to 18 deaths in New York City. Nevada’s Incline Village and the Port of San Diego banned e-bikes in areas where pedestrians travel.⁷ 

Key Decision Points Surrounding E-Bike Use in the US

Policymakers in the US have several key decision points:

Extending Helmet Laws

Helmet mandate legislation is effective, with an estimated 20% reduction in head injuries and a larger effect with more severe injuries. Any person under age 17 is required to wear a helmet when riding bikes in California, and all Class 3 e-bike riders, regardless of age, must wear a helmet. Law enforcement should be supported to enforce existing helmet laws, as it can be difficult to distinguish e-bike classes from afar. Requiring the use of motorcycle helmets that protect both the skull and neck should be considered for faster e-bikes.

Enforcing Speed and Rider Limits

Several devices are marketed to bypass existing speed restrictions. “Tuning kits” can deactivate the speed limiter, turning a lawful e-bike into a nonstreet-legal motorcycle or moped. E-bike manufacture and product safety standards should be strengthened to prevent disabling the speed limiter, with fines for removing speed regulators. Restrictions on the number of individuals allowed on a single e-bike should be strengthened, as multiple riders are hazardous.

Changing Nomenclature

New “multiclass” e-bikes can operate across multiple e-bike classes. “Out of class” e-bikes also exist with motors more than 750 watts that do not conform to the current manufacturer classification and reach speeds of motorcycles. Perhaps using the names “e-moped” or “e-motorcycle” would provide greater clarity to purchasers about the risks of these vehicles.

Requiring Licenses for E-Bike Operation

Licensing and registration requirements for e-bike users under the age of 18 (or for all ages) are under consideration.

Improving Road Safety Design

Infrastructure and road safety are central. Urban design can promote bicycle lanes and safe routes for e-bikes to travel. An unanswered question is the role of traffic accidents in the injuries being witnessed, and what steps to promote road safety should be prioritized. Should e-bikes travel on sidewalks and boardwalks or in streets, in protected bike lanes, and be allowed on multi-use trails and unpaved roads in open spaces?

Increasing Education and Awareness

E-bikes are commonly sold in bike shops or online without special license or training requirements. Regulations and community understanding of risks have not kept pace with the surge in use, and greater public education efforts are necessary. First-time violators could undergo special education or take an approved safety course when they receive citations for riding against traffic, on sidewalks, without helmets, and so on.

Standardizing Laws

The wide variability in international and state laws should be addressed to promote rider safety and assist law enforcement. Currently, there is confusion as rules differ across the three different categories of e-bikes and across adjacent communities.

California ACS Surgeon Advocacy and AB 1778

In 2021, the death of a 12-year-old after a Class 2 e-bike crash (while a helmeted passenger) catalyzed a statewide discussion of e-bike hazards. In August 2022, the city of Carlsbad approved an emergency declaration on e-bike safety after two deaths in a 17-day period. In June 2023, the city of Encinitas declared a local state of emergency regarding e-bikes after the death of a 15-year-old. Later in 2023, SB 381 by California Senator David Min commissioned the Mineta study to investigate e-bike policy and inform efforts to improve the safety of e-bike users. 

In December 2023, Northern California ACS members joined Marin Assemblyman Damon Connolly at the press conference when AB 1778 was introduced. This legislation will create an e-bike enforcement pilot program in Marin County to prohibit a person under the age of 16 from operating a Class 2 e-bike, to align with Class 3 e-bike laws.

Current California law does not impose an age restriction to operate a Class 2 e-bike, which may help explain the rise in serious injuries and deaths. In 2024, the three California ACS Chapters joined as sponsors of AB 1778 and testified in support before the Senate Transportation Committee. The bill passed unanimously. Three other e-bike bills are currently under consideration in California (see Table 3).

A review of the Congressional legislative database by the ACS Division of Advocacy and Health Policy revealed that a majority of proposed federal legislation supports e-bikes, by designating areas in national forests where their use is permitted, extending grants for e-bike share programs, or creating tax credits for individual purchase. 

One bill seeks to strengthen safety standards by preventing the evasion of speed limitations through a switch or manufacturer-provided software. A review of the statewide legislative database revealed that as of April 2024, New Hampshire, New Jersey, and New York are considering legislation to require e-bike registration. Florida and New York are considering licensure, and some states are considering insurance and age restriction requirements similar to California.

Next Steps for Surgeons

Surgeons can help prevent e-bike injuries by:

• Catalyzing public education safety campaigns
• Assembling scientific evidence to inform policymakers
• Speaking about safety during ACS state advocacy days
• Working with the ACS to update its Statement on Bicycle Safety and the Promotion of Bicycle Helmet Use¹⁰
• Collaborating with scientific and epidemiology partners, including the American Academy of Pediatrics, Centers for Disease Control and Prevention, and public health officials
• Working with policymakers, elected officials, Congress, and officials such as Transportation Secretary Pete Buttigieg

The rise in e-bike use, especially among children and adolescents, presents a significant public health challenge due to the associated increase in injuries and fatalities. The lack of uniform regulation and enforcement across jurisdictions exacerbates these risks. While e-bikes offer economic and environmental benefits, their higher speeds and potential for severe injuries necessitate urgent action. Policymakers must address key issues such as helmet mandates, speed regulations, and public education to enhance safety. And importantly, surgeons and public health officials play a crucial role in advocating for these changes to mitigate the risks and ensure safer e-bike use globally.

Dr. John Maa is past-chief of general and acute care surgery at MarinHealth Medical Center in Greenbrae, CA, and a Past-President of the ACS Northern California Chapter.

Dr. Jay Doucet is chief of the Division of Trauma, Surgical Critical Care, Burns, and Acute Care Surgery and medical director of emergency preparedness and response at the University of California San Diego Health.

References

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2. US Federal Register. Electric bicycles; advance notice of proposed rulemaking; request for comments and information. Available at: https://www.federalregister.gov/documents/2024/03/15/2024-05472/electric-bicycles-advance-notice-of-proposed-rulemaking-request-for-comments-and-information. Accessed June 6, 2024.
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7. Maa J, Alfrey E. Marin Voice: Trauma surgeons make plea for more e-bike safety. Marin Independent Journal. December 6, 2023. Available at: https://www.marinij.com/2023/12/06/marin-voice-trauma-surgeons-make-plea-for-more-e-bike-safety/. Accessed June 6, 2024.
8. Collins K. Why bicycle deaths in New York City are at a 24-year high. New York Times. March 7, 2024. Available at: https://www.nytimes.com/2024/03/05/nyregion/nyc-cyclist-deaths-ebike.html#. Accessed June 6, 2024.
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10. American College of Surgeons. Statement on Bicycle Safety and the Promotion of Bicycle Helmet Use. March 15, 2023. Available at: https://www.facs.org/about-acs/statements/statement-on-bicycle-safety-and-the-promotion-of-bicycle-helmet-use/#. Accessed June 6, 2024.