A surge in the use of electric bicycles throughout the United States is prompting cities to revise regulations that restrict their use, including bans against riding them on sidewalks and trails.The nation’s capital and other Washington-area jurisdictions are among those taking steps to modernize and streamline policies that advocates say are outdated, set unrealistic restrictions and confuse riders of the bikes that can be run on electric power as well as by pedaling."The number of bicyclists in the U.S. is growing, in part because of the rise of e-bikes, but it is difficult for people to know where they are allowed to ride them," said Morgan Lommele, with the cycling advocacy group PeopleForBikes. "The laws are all over the place for electric bicycles."About half of U.S. states classify e-bikes as motor vehicles, requiring licensing, registration and even insurance - and essentially making them illegal to ride, said Lommele. Others put pedal-assist e-bikes with speeds up to 20 mph in the same category as regular bicycles, allowing them to share the same road infrastructure.The Washington region falls in the middle, with regulations that aren’t as troubling to riders but also not ideal, bike advocates say. Generally, in the District and some of its suburbs, e-bikes are not permitted on trails and sidewalks. The National Park Service, which operates major bike paths in the region, including the 18-mile Mount Vernon Trail, also bans the motorized bicycles. And so do the park systems in Montgomery and Prince George’s counties in Maryland and Fairfax County in Virginia.But changes may be coming as some jurisdictions move to allow e-bikes on trails as soon as this year and others explore the possibility. Transportation officials say they can’t ignore the demand for e-bikes if they want to encourage bike commuting."We want to try to support the new interest in electric bikes and have one more way for people to get out on bikes," said Jim Sebastian, who oversees bike infrastructure at the D.C. Department of Transportation. "Not only are we seeing more e-bikes, we also have electric bike-sharing in town. So we want to modernize our regulation."In the District, transportation officials say they are drafting new rules to allow the pedal-assist bikes on trails and possibly sidewalks outside the downtown area, where conventional bikes are allowed. Montgomery adopted new park rules last year that give the county discretion to open trails to e-bikes on a case-by-case basis, and Montgomery Parks and Planning is set to begin that process on less-used trails this year, moving gradually to the most popular ones, such as the Capital Crescent Trail.A Prince George’s Parks official said the conversation about the use of e-bikes on county trails has not occurred. Arlington does not have a policy regarding the use of e-bikes, but it is researching the subject.The Fairfax County Park Authority said e-bike riders have asked for the policy to be changed to allow them on popular commuting trails. The authority is reviewing the pros and cons of the change and the possible conflicts with other trail users, spokeswoman Judy Petersen said."It may be in the end that we designate areas where this is acceptable, allowed and safe," she said.Jenny Anzelmo-Sarles, a spokeswoman for the National Park Service, said the agency is tracking what surrounding jurisdictions are doing."Everybody is thinking about it," said Casey Anderson, chair of the Montgomery Planning Board.And it’s not just locally. There’s a growing campaign for more e-bike-friendly policies all across the U.S. In New York, Mayor Bill de Blasio announced this week that the city will legalize the use of pedal-assist electric bikes, shifting its hard-line stance of the past few months in which it ramped up enforcement against users.Eight states, including California, Illinois and Colorado, have passed advocate-backed legislation in the past three years, setting clear rules on how and where to ride e-bikes.In some states, including South Carolina and Alabama, e-bikes are subject to the registration, licensing and insurance requirements that apply to motor vehicles, yet their departments of motor vehicles do not recognize e-bikes as vehicles and have no system for supplying registration and licensing. This makes riding the bikes in those states illegal, said Lommele, who has been lobbying states to change the rules.E-bikes have long been popular in Europe and China, and they’ve grown more popular in the United States in the past several years along with Americans’ love of biking. Research by the National Institute for Transportation and Communities recently found that people buying e-bikes are reducing their reliance on cars.Users say electric bikes eliminate barriers for people who may be discouraged from riding a traditional bicycle because of age, disability or limited physical fitness. Some commuters also prefer them because they make for a less strenuous (i.e., sweaty) ride.But they aren’t without critics. Many pedestrians don’t want to share sidewalks with motorized bikes. Some biking enthusiasts consider motorized bikes cheating or don’t want to share already crowded bike paths with vehicles that travel faster than conventional bikes. Others, particularly in law enforcement, are concerned about speed enforcement and the risk of crashes.Aware of the existing conflicts, some jurisdictions are being cautious in extending the two-wheel vehicles access to public infrastructure. In Montgomery County, for example, there is a long history of complaints about bikes on natural-surface trails shared with hikers and horse riders. E-bikes will add another complication."We want to take it gradually so we don’t provoke a backlash against e-bikes and bicycles in general," Anderson said. "Eventually, we will get to the point where most trails will allow e-bikes if not all of them."Officials say e-bike riders can be cited for riding where they are not allowed, but add they are not cracking down or prioritizing enforcement of these rules.The pedal assist, the most popular e-bike, has a motor that can generate speeds of up to 20 mph. It is known as a class 1 e-bike, with a motor that helps users overcome hilly stretches of road or give those physically challenged a boost. But advocates say they go just a few miles faster than a regular bicycle. The class 2 e-bike can be activated through a throttle such as a trigger or button, and does not require pedaling to engage the motor, but it also has the 20-mph speed cutoff. The class 3 has a larger motor that allows speeds up to 28 mph - and should only be ridden on streets, advocates say.Bikeshare operators are adding e-bikes to their fleets, recognizing that "people gravitate toward them," said Samantha Herr, executive director of the North American Bikeshare Association."They are fun and reduce common barriers to bicyclists," she said.JUMP, one of five dockless bike operators in the District, brought its e-bikes to the city last fall, and it has become one of the most popular services, officials said. Each JUMP bike averages 3.5 trips daily, nearly twice that of dockless conventional bikes, and they are traveling an average of 11 miles per day, compared to 1.5 miles for Capital Bikeshare, according to a company analysis.LimeBike and Spin, which also operate dockless bikes in Washington, have introduced e-bikes in other markets and could bring them to the District. And Motivate, which operates major public bike-sharing systems including the Washington region’s Capital Bikeshare, is introducing e-bikes in San Francisco, where the company says they will help riders traverse the city’s notorious hills."We are seeing them as a whole different mode from traditional cycling. You have the ability to cover much hillier terrain and people of all fitness levels can use them," said Julie Wood, a spokeswoman for New York-based Motivate. For riders it’s not only fun, she said, "you feel invincible, you have this secret weapon."