Electric-assist bikes

Electric bicycles or electric-assist bicycles, often called e-bikes, are becoming increasingly popular because they can make biking easier or more comfortable, which potentially allows for a greater diversity of bicycle trips and riders. E-bikes are even starting to be integrated into bike sharing systems with Birmingham, Baltimore, Park City, and the University of Tennessee at Knoxville leading the way in the U.S.

E-bikes include a small electric motor that is engaged by pedaling or by a device on the bike's handlebar such as a throttle or switch. Generally, e-bikes look very similar to standard bicycles and a standard bicycle can be converted into an e-bike. The top speed for most e-bikes is between 20 and 28 miles per hour. Maximum speed is particularly important to the classification and regulation of e-bikes. While regulations vary by state and municipality, at the Federal level, e-bikes are considered to have a maximum speed of 20 miles per hour when powered exclusively by motor.

According to PeopleForBikes, five states have model legislation that regulates e-bikes by three classifications and more than 20 states regulate e-bikes as conventional bicycles. The remaining states have sometimes confusing laws that may classify e-bikes somewhere among mopeds and scooters. Some municipalities also have special e-bike laws, which typically regulate use on trails, paths, and sidewalks. After a one-year study period, Boulder, Colorado, adopted legislation allowing e-bikes on multi-use paths, but not in open space or mountain park lands.

Resources

PeopleForBikes
The Electric Bicycles page by PeopleForBikes contains up-to-date information on federal and local e-bike policies as well as resources for e-bike retailers and people interested in electric mountain bikes.

National Conference of State Legislature
State Electric Bicycle Laws—a legislative primer: This report offers in-depth discussion of the legal regulations that pertain to e-bikes.

Federal Highway Administration
Framework for Considering Motorized Use on Nonmotorized Trails and Pedestrian Walkways: Official guidance from the FHWA for permitting e-bikes on nonmotorized paths.

Portland State University
PSU and its affiliates, the National Institute for Transportation and Communities and the Transportation and Research Education Center, provide much of the leading research for e-bikes.
Electric Bicycle Research Hub
Regulations of E-Bikes in North America (2014)

Light Electric Vehicle Education + Research
The LEVER Initiative is a consortium of researchers and educators from University of Tennessee, Portland State University, and Monash University who are answering some of the biggest questions related to these emerging technologies.

Research

Evaluation of an Electric Bike Pilot Project at Three Employment Campuses in Portland, Oregon (2017): Findings from the National Institute for Transportation and Communities show e-bike ownership can foster longer bicycle trips and trips by a wider range of users.

Motives, perceptions and experiences of electric bicycle owners and implications for health, wellbeing and mobility (2016): This paper from the Journal of Transport Geography analyzes interviews with e-bike owners in the UK and the Netherlands.

Risky riding: Naturalistic methods comparing safety behavior from conventional bicycle riders and electric bike riders (2015): This study published in Accident Analysis & Prevention finds e-bike riders do not differ from conventional bicycle riders in terms of safety behavior.

Electric bikes in North America: results of an online survey (2014): In this TRB paper, Portland State University researchers conclude e-bikes help bicyclists take more trips, longer trips, and carry more cargo.