The National Park Service (NPS) has been at the forefront of the e-bike debate in the United States by permitting these modern marvels of micro-mobility on trails in national parks where regular, "analog" bike use is allowed.
The park service has produced a detailed literature overview of nearly 60 e-bike studies. The literature review revealed the following conclusions related to the environment and e-bikers.
Environment and E-bikes
"E-bike adoption can play a role in decreasing non-renewable energy use."
"E-biking, Environment and Natural Resources
- E-bikes have order-of-magnitude lower lifecycle greenhouse gas and air pollutant emissions than internal combustion engine vehicles, but higher emissions than traditional bicycles.
- The extent of environmental benefits of e-bikes depends on mode shift behavior (i.e., substitution of trips that would have otherwise been taken using a different mode), degree of e-bike market penetration, and attributes of electricity generation.
- Research suggests that e-bikes are most commonly replacing trips taken by traditional bicycles, but are also likely leading to a reduction in vehicle miles traveled, because e-bikes enable users to bike more often, travel longer distances, and carry more cargo.
E-biking and Trail Surfaces
- One study found that there was not a significant difference in soil displacement on natural surface trails between e-mountain bikes (eMTBs) and traditional mountain bikes.
- Management best practices indicate that traditional mountain bike degradation can be minimized if trail users are restricted to formal trails (in contrast to visitor-created trails).
- A study of traditional mountain biking effects observes that trail design and management contribute more significantly to trail surface degradation than the type or amount of use.
E-biking, Wildlife and Vegetation
- Research on traditional mountain bikes shows that their presence can disturb wildlife and effect ecosystems, similar to other forms of non-motorized recreation.
- One literature review, finding no evidence that noise, speed, and trail effects were dissimilar between e-bikes and traditional bicycles, stated that the expected ecological effect of e-bikes would be similar to traditional bicycles.
- There have been no fire incidents reported with e-bike devices that adopted the voluntary electrical standard (e.g., UL 2272) for micro-mobility devices."
"Like traditional bicycles, e-bikes can decrease traffic congestion, reduce the demand for parking spaces, and increase the number and visibility of bicyclists on the road. Researchers have analyzed both the emissions, energy, and broader environmental effects associated with e-bike use as well as longer term life cycle effects such as production, maintenance, and disposal of e-bikes. This theme of the literature review addresses how e-bikes, compared to internal combustion engine (ICE) vehicles, “consume less energy, emit less carbon dioxide (CO2), and decrease exposure to pollution.”
Like other recreational uses of trails, e-bikes have the potential to affect natural resources and trail surfaces in a manner similar to traditional bicycles. Natural surface trail erosion from bike tires, noise from the mechanical operation of the bike, or other effects to flora and fauna from the presence of a bike may exist."
Environment and Natural Resources Key Findings
"Energy, Emissions, and Climate Key Findings
The existing research supports the conclusion that e-bike adoption can play a role in decreasing non-renewable energy use. E-bikes produce more emissions and use more energy throughout their lifespans than traditional bicycles. However, compared to motorized forms of outdoor recreation, such as ATVs and motorcycles, e-bikes produce fewer pollutants and greenhouse gas emissions. E-bikes also produce significantly fewer emissions and pollutants than gas-burning cars.
To the extent that e-bike trips replace motor vehicle trips, e-bikes can help support NPS active transportation and sustainability goals, while also improving air quality for greater natural resource protection and an improved visitor experience. The magnitude of the environmental benefit provided by e-bikes depends on the overall “mode shift” that occurs between motorized and non- motorized forms of transportation and recreation. Mode shift refers to substitution of one form of transportation for another. Two studies found that increased e-bike use resulted in decreased car use.
Energy, Emissions, and Climate Areas for Further Research
There is a lack of research analyzing e-bike emissions and pollution in outdoor recreational contexts. Most studies on this topic consider e-bikes in the transportation context. For instance, it is possible that emissions findings could be different for natural trail surfaces than for paved roadways.
The mode shift of e-bikes in an outdoor recreational context is also unknown. Researchers have not yet determined whether increased e-bike use displaces motorized recreation (such as ATVs) or substitutes for other non-motorized recreation (such as traditional bicycles) E-bike use may also create new recreational trips that would not have occurred otherwise."
"Trail Surfaces Key Findings
The existing research on e-bikes provides an initial indication that e-bikes have natural trail surface effects not significantly different from traditional bicycles. One study found that e-bikes and traditional bicycles generally cause the same amount of degradation as hiking, and both activities cause less trail degradation than horseback riding or motorized activities.
A review of mountain biking effects on trail surfaces arrived at the following main conclusions:
1) Management best practices indicate that degradation can be minimized if trail users are restricted to formal trails (in contrast to visitor-created trails); and 2) Trail design and management contribute more significantly to trail surface degradation than the type or amount of use.
Trail Surfaces Areas for Further Research
Additional research could assess effects on specific types of trail surfaces by recreational activity, including a comparison between e-bikes and traditional bicycles. There is also a lack of research documenting the long-term effects, if any, of e-bikes on trail surfaces. Such research could aid managers with understanding appropriate management actions to mitigate adverse effects of outdoor recreation on trail surfaces."
Academic Research – User Conflicts: Most Other Trail Users Cannot Differentiate Between a Traditional Bicycle and an E-bike on Trails
Academic Research – Safety: E-bikes Generally Travel at Speeds Similar to Traditional Bicycles on Roadways, Off-street Paths, and Natural Surface Trails
Academic Research – Nature and Environment: E-bikes Have Order-of-Magnitude Lower Lifecycle Greenhouse Gas and Air Pollutant Emissions than Internal Combustion Engine Vehicles
Academic Research – Equality: The Gender Discrepancy Between E-bike Users is Proportionally Lower than that of Traditional Bicycle Users in the United States
Academic Research – Access: E-bikes Provide a New Option to Cycle Regardless of Physical Fitness, Age, Disability, Recent Injury, High Altitude, or Challenging Terrain
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"Wildlife and Vegetation Key Findings
Research on outdoor recreation, on average, found that different types of non-motorized recreation (hiking, traditional mountain biking, and horseback riding) had similar levels of wildlife disturbance. ATV riding was found to be the most disruptive form of outdoor recreation for wildlife across all studies. Some studies found that traditional mountain biking had wildlife effects similar to ATVs depending on the time of day and the variables being measured.
There is a risk of fire from lithium batteries on e-bikes. Aftermarket additions used to retrofit traditional bikes into e-bikes may also present a fire risk. However, there have been no fire incidents reported with e-bike devices that adopted the voluntary electrical standard for micromobility devices (UL 2272).
One literature review, finding no evidence that noise, speed, and trail effects were dissimilar between e-bikes and traditional bicycles, stated that the expected ecological effect of e-bikes would be similar to traditional bicycles.
Wildlife and Vegetation Areas for Further Research
There is not yet any research available which specifically measures e-bike effects to wildlife and vegetation, so the specific effects of e-bikes on the ecological system are still not well understood. There is a lack of research studying potential e-bike effects such as noise and plant trampling compared to traditional bicycling, mountain biking, or other forms of non-motorized outdoor recreation."
"This theme summarizes studies about the potential effects of e-bikes on energy, emissions, and climate; trail surfaces; and wildlife and vegetation. It also highlights several studies about related recreational activities and their effects on the environment and natural resources."
Energy, Emissions, and Climate
MacArthur, J., McQueen, M., & Cherry, C. (2019). The E-Bike Potential: Addressing Our Climate Crisis by Incentivizing Active Transportation. Transportation Research and Education Center. https://trec.pdx.edu/news/e-bike-potential-addressing-our-climate-crisis- incentivizing-active-transportation
"This white paper explores the potential effects from e-bikes on person miles traveled (PMT) and greenhouse gas (GHG) emissions using a model for PMT shift and GHG reduction potential created for Portland, Oregon. The findings from the report suggest that a 15%-point increase in e- bike mode share would result in an approximately 10%-point decrease in PMT by car.
Additionally, the research found that a 15%-point increase in e-bike mode share results in an 11% decrease in carbon dioxide emissions. The research shows that increasing the e-bike mode share is a beneficial way to meet carbon emission reduction goals and reduce driving; however, substantial political will is needed to promote a level of e-bike ridership necessary to realize the potential for e-bikes to reduce GHG emissions."
Abagnale, C., Cardone, M., Iodice, P., Strano, S., Terzo, M., & Vorraro, G. (2015). A Dynamic Model for the Performance and Environmental Analysis of an Innovative e-bike. Energy Procedia, 81, 618–627. https://doi.org/10.1016/j.egypro.2015.12.046
"Researchers conducted tests identifying the “well-to-wheel” emissions reductions that could be achieved by replacing trips made by a moped with a four-stroke engine with an e-bike. “Well-to- wheel” analysis considers energy and emissions associated with the use phase of the lifecycle (and not production and end-of-life considerations). The study measured reductions in the amount of measured carbon dioxide, nitrous oxide, and hydrocarbons. These results suggest that increased e- bike use may provide a net reduction in well-to-wheel emissions if it substitutes for other travel modes."
Machedon-Pisu, M., & Borza, P. N. (2020). Are Personal Electric Vehicles Sustainable? A Hybrid E-Bike Case Study. Sustainability, 12(1). https://doi.org/10.3390/su12010032
"The results of this study found that e-bikes consume less energy and produce dramatically less pollution during their lifespans than traditional vehicles. Researchers built their own e-bike and compared e-bikes to 1) cars, trains, trams, trucks, and buses; 2) medium and heavy duty EVs; 3) motorcycles, big scooters, and mopeds; and 4) motorbikes and small scooters with respect to air pollution and energy consumption. The study accounted for emissions and energy use during production, use, disposal, and refueling/charging of each vehicle."
Woodcock, J., Abbas, A., Ullrich, A., Tainio, M., Lovelace, R., Sá, T. H., Westgate, K., & Goodman, A. (2018). Development of the Impacts of Cycling Tool (ICT): A modelling study and web tool for evaluating health and environmental impacts of cycling uptake. PLOS Medicine, 15(7). https://doi.org/10.1371/journal.pmed.1002622
"This study modelled how CO2 emissions would change in England if increasing proportions of the population had the same distance-based propensity to cycle as existing cyclists. If the proportion of the English population who cycled regularly increased from 4.8% to 25%, the model predicted a 2.2% reduction in car miles. If the new cyclists had e-bikes, the reduction in vehicle miles travelled would be 2.7%. These results suggest that the adoption of e-bikes can help reduce vehicle miles travelled and thus reduce overall vehicle emissions."
Li, T. Z., Qian, F., & Su, C. (2014). Energy Consumption and Emission of Pollutants from Electric Bicycles. Applied Mechanics and Materials, 327–333. https://doi.org/10.4028/www.scientific.net/AMM.505-506.327
"This study analyzed the energy consumption and pollution emissions at different stages of the e- bike life cycle (production, use, maintenance, and recycling). Results revealed that most energy consumption by e-bikes occurs during the use stage. The emissions of pollutants by e-bikes per person per kilometer are several times lower than emissions from motorcycles and cars, equivalent to buses, and higher than traditional bicycles. These results suggest that shifts from personal vehicles can help reduce overall emissions and pollutants."
McCarren, T., & Carpenter, N. (2018). Electric bikes: Survey and energy efficiency analysis. Efficiency Vermont. https://www.efficiencyvermont.com/Media/Default/docs/white-papers/efficiency-vermont- electric-bike-white-paper.pdf
"This survey asked 90 e-bike owners from Vermont questions about their e-bike use and general travel behaviors. Results revealed that the average respondent displaced 760 miles of driving annually with an e-bike. This suggests that increased e-bike adoption can significantly reduce overall emissions by enabling users to switch from personal vehicles."
Ji, S., Cherry, C. R., Bechle, M. J., Wu, Y., & Marshall, J. D. (2011). Electric Vehicles in China: Emissions and Health Impacts. Environmental Science and Technology, 46(4), 2018– 2024. https://doi.org/10.1021/es202347q
"Researchers compared emissions and environmental health effects of e-bikes to electric vehicles, gasoline cars, diesel cars, and diesel buses across 34 major Chinese cities. CO2 emissions were an order of magnitude higher for all vehicles compared to e-bikes. Other emissions, such as particulate matter, nitrous oxide, and hydrocarbons were also substantially lower for e-bikes than traditional vehicles. The results emphasize the ability of e-bike adoption to dramatically reduce overall emissions and health effects from the transportation system."
Weiss, M., Dekker, P., Moro, A., Scholz, H., & Patel, M. K. (2015). On the electrification of road transportation—A review of the environmental, economic, and social performance of electric two-wheelers. Transportation Research. Part D, Transport and Environment, 41, 348–366. https://doi.org/10.1016/j.trd.2015.09.007
"Researchers reviewed e-bike (with a maximum assisted speed of 25km/hr), electric moped, and electric motorcycle performance on several factors including energy and emissions. The study found that e-bike adoption can reduce human exposure to polluting emissions compared to internal combustion engine vehicles. It also found that e-bikes resulted in 50-90% energy savings compared to gas-burning mopeds and motorcycles."
International Mountain Bicycling Association. (2015). A Comparison of Environmental Impacts from Mountain Bicycles, Class 1 Electric Mountain Bicycles, and Motorcycles: Soil Displacement and Erosion on Bike-Optimized Trails in a Western Oregon Forest. https://www.americantrails.org/images/documents/A-Comparison-of-Environmental- Impacts-from-Mountain-Bicycles-Class-1-Electric-Mountain-Bicycles-and-Motorcycles.pdf
"This study, completed by a mountain biking advocacy organization, is currently the only source identified which specifically measured the effect of e-bikes on natural surface trails. Soil erosion from Class 1 e-mountain bikes was not significantly different from erosion caused by traditional mountain bikes. Researchers conducted soil erosion tests on a test trail, controlling for several factors including soil type, soil moisture, level of use, trail grade, wheel size, rider weight, tire pressure, and tire make/model. Given the controlled environment of the test trail, these results may not be consistent across all trail types and conditions; further study could help generalize these findings."
Nielson, T., Palmatier, S. M., & Proffitt, A. (2019). Literature Review: Recreation Conflicts Focused on Emerging E-Bike Technology. https://assets.bouldercounty.org/wp- content/uploads/2020/01/e-bike-literature-review.pdf
"The goal of this literature review was to inform policy discussions and decisions for the quickly growing e-bike market in four of Colorado’s northern Front Range open space programs. Boulder County, Colorado’s literature review identified no significant difference in effects to wildlife or trail surfaces between traditional bicycles and e-bikes.
The review stated, “Given that e-bikes are very similar to traditional bicycles in terms of noise, trail effect, and speed, it is fair to say that their effect on wildlife habitats would be similar to other non-motorized bicycles” based on a study of recreational disturbance of deer and elk. The literature review also found that trail users were likely to have concerns about noise and trail degradation caused by e-bikes. However, since the literature review authors found few impacts from e-bikes, the review observed that “public perception surrounding e-bikes’ [noise, trail surface, and speed] effect[s] may be at odds with observed effects.” "
Chavez, D., Winter, P., & Bass, J. (1993). Recreational Mountain Biking: A management perspective. Journal of Park and Recreation Administration, 11(3), 8. https://www.americantrails.org/images/documents/psw_1993_chavez001.pdf
"This study analyzed responses from a telephone survey of recreation land managers across the United States regarding perceptions of mountain biking and effect on trail surfaces. While many respondents reported moderate to extensive mountain bike use in their resource areas, most did not have designated mountain bike areas.
About one-third reported resource degradation attributable to mountain bike use. Few reported having management plans specifically related to mountain biking. This study did not address e-bikes specifically; however, it revealed a need for greater awareness and planning by land managers for emerging modes of recreation."
International Mountain Bicycling Association. (2016). Trail Use and Management of Electric Mountain Bikes: Land Manager Survey Results. https://www.americantrails.org/images/documents/TrailUseEMTBs.pdf
"This study conducted a survey of land managers across the United States. Results revealed that very few land managers had any direct experience with e-mountain bikes (eMTB). 89% of surveyed land managers expressed some level of concern about the environmental effect of eMTBs. 91% of respondents reported that environmental effect and social effect studies of eMTBs would help inform their trail management practices. The responses to this survey reveal a widespread interest among land managers in learning more about the effects of eMTBs."
Newsome, D., & Davies, C. (2009). A case study in estimating the area of informal trail development and associated impacts caused by mountain bike activity in John Forrest National Park, Western Australia. Journal of Ecotourism, 8(3), 237–253. https://doi.org/10.1080/14724040802538308
Researchers developed a rapid assessment tool which used GPS and GIS technology to quantify the total amount of land effected by mountain bike use at a recreational park in Australia. The study did not measure specific environmental effects, but the tool effectively quantified the area effected by the creation of mountain bike-specific informal trails and trail modifications The study also did not involve e-bikes, but mapping tools like the kind developed in this study may be useful in assessing short- to long-term effects of e-bikes and e-mountain bikes outside designated natural surface or paved trails."
Wildlife and Vegetation
Larson, C. L., Reed, S. E., Merenlender, A. M., & Crooks, K. R. (2016). Effects of Recreation on Animals Revealed as Widespread through a Global Systematic Review. PLOS ONE, 11(12). https://doi.org/10.1371/journal.pone.0167259
"This literature review identified 274 articles on the effects of both motorized and non-motorized non-consumptive recreation to animals. 93% of reviewed articles documented at least one effect of recreation on animals. 59% of these effects were classified as negative. The study identified that, although motorized and non-motorized activities had similar evidence for overall effects on wildlife, non-motorized had greater negative effects, counter to what may be expected.
The study finds that, although motorized activities may be expected to be more harmful to animals because of vehicle speed and noise, this is not the case. The researchers acknowledge that motorized activities likely occur on larger spatial scales, and that the studies reviewed did not compare effects across spatial scales. The review did not include any studies specifically referring to e-bikes."
Thurston, E., & Reader, R. J. (2001). Impacts of experimentally applied mountain biking and hiking on vegetation and soil of a deciduous forest. Environmental Management, 27(3), 397–409. https://doi.org/10.1007/s002670010157
"This experiment compared the effects of mountain biking (though not e-bikes specifically) and hiking on understory vegetation and soil in an off-trail area of a deciduous forest. Researchers controlled for the intensity of activity. The immediate effects of both activities were severe, but quick recovery could be expected when the activities are disallowed. Results revealed that at similar intensities of activity, the short-term effects of mountain biking and hiking may not differ greatly in undisturbed (i.e., off-trail) areas of deciduous forests. It is not clear if these results hold true in other environments or with more intense activity over time."
Marion, J., & Wimpey, J. (2017). Environmental Impacts of Mountain Biking: Science Review and Best Practices. https://www.anacorteswa.gov/DocumentCenter/View/16528/EIS-mountain-bikes-and-Best- Practices
"This literature review examined effects to vegetation, soil, water, and wildlife as a result of mountain bike use. Fifteen mountain bike-specific studies were found. The review found no significant difference in plant density change or soil loss between hiking and mountain biking. The review also found that effects to wildlife were similar between hikers, mountain bikers, and other non-motorized trail users. This study did not look at e-bikes, but it identified several trail management implications that could be applicable to eMTBs."
Wisdom, M., Ager, A., Preisler, H., Cimon, N., & Johnson, B. (2004). Effects of Off-road Recreation on Mule Deer and Elk. North American Wildlife and Natural Resources Conference. https://www.fs.fed.us/pnw/pubs/journals/pnw_2004_wisdom001.pdf
"Researchers measured the effects of ATV riding, hiking, traditional mountain biking, and horseback riding on elk and deer movement in a controlled study forest in Oregon. Researchers did not specifically test e-bikes. All off-road activities resulted in substantial elk movement compared to a control period. Movement rates were much lower for deer, suggesting different behavioral responses by species to off-road non-consumptive recreation. Mountain bikes produced more disturbance than hiking and horseback riding and less disturbance than ATV riding. However, the effect of mountain biking was more similar to hiking and horseback riding, while animal movement rates for ATV riding were dramatically higher than all other activities."
Naylor, L. M., J. Wisdom, M., & G. Anthony, R. (2009). Behavioral Responses of North American Elk to Recreational Activity. Journal of Wildlife Management 73(3), 328–338. https://doi.org/10.2193/2008-102
"This study measured the movement of elk in response to ATV riding, hiking, traditional mountain biking, and horseback riding. The effects of ATV riding were higher than other activities. The effects of mountain biking were higher, on average, than the effects of hiking and horseback riding. The study did not specifically measure e-bikes, though it includes discussion of implications for the management of recreational activity."
Wisdom, M., Preisler, H., Naylor, L., Anthony, R., Johnson, B., & Rowland, M. (2018). Elk responses to trail-based recreation on public forests. Forest Ecology and Management, 411, 223–233. https://doi.org/10.1016/j.foreco.2018.01.032
"Researchers measured the movement of elk in response to ATV riding, hiking, traditional mountain biking, and horseback riding. The study did not specifically measure e-bikes. ATV riding was found to have the most disturbance on wildlife, followed by mountain biking, horseback riding, and hiking.
During some times of day, the disturbance caused by mountain biking was closer to the disturbance caused by ATV riding. At other times, the effects of mountain biking were closer to those observed for hiking and horseback riding. The study discusses management implications for land managers and suggests a need for more research documenting the wildlife effects of outdoor recreation."
Dawson, A. (2019). E-Bike Battery Explodes, Burning 79-Year-Old Cyclist and Causing Bushfire. Bicycling. https://www.bicycling.com/news/a25890860/electric-bike-explodes/
"This anecdotal news article describes an incident of a lithium e-bike battery igniting while the cyclist was riding on a roadway and caused a fire in dry vegetation adjacent to the road. The battery had been added to a traditional bicycle through an after-market third party. These aftermarket devices, which can be used to modify traditional bikes may pose an additional fire risk."
U.S. Consumer Product Safety Commission. (2020). Safety Concerns Associated with Micromobility Products. https://cpsc.gov/s3fs-public/Report-on-Micromobility- Products_FINAL-to-Commission.pdf
"A report commissioned by the Consumer Product Safety Commission warned that micromobility products, including e-bikes, may pose hazards. The report does not address wildfire risk but focuses on fire safety hazards and property damage due to battery failures and mechanical battery- mounting issues. However, the vast majority of reported safety concerns occurred before the development of voluntary electrical standards for e-bikes (e.g., UL 2272, “Electrical Systems for Personal E-Mobility Devices”). There were no concerns reported with devices that used the voluntary standard."
This is an interactive version of the NPS study. We have copied the text of the study verbatim on this page under Section 105 of the U.S. Copyright Act. The text and conclusions of the study are those of the NPS.
Krista Sherwood (Conservation & Outdoor Recreation Division) and Wayne Emington (Park Facility Management Division) are the points of contact for this outstanding literature review. The NPS is not affiliated or associated with E-bike Lovers.
Download the NPS study here.