Indeed, the e-bike market is so broad today that every major brand, even those traditionally associated with dedicated cycling enthusiasts, has jumped onto the e-bike saddle.

“E-mountain bikes these days are super popular,” said Dominik Geyer of Specialized, whose company did some soul searching before developing its own e-bikes. But now even advocacy groups like the International Mountain Bicycling Association have abandoned their anti-e-bike stance and now support the use of pedal-assist bikes on some trails.

E-bikes can enhance the cycling experience for all kinds of riders, from novices to committed commuters who want to extend their routes without arriving at the office soaked in perspiration, said Murray Washburn, the director of global marketing for Cannondale. The technology also encourages owners to ride more often, safe in the knowledge that they can get a boost should they encounter steep hills or become fatigued far from home.

Improved technology has also helped their popularity. Manufacturers have switched from motors attached to the hub of the rear wheel to more efficient center-drive motors in the pedal crankshaft, which improve the bike’s center of gravity and handling. New lithium ion batteries are more efficient and able to deliver greater range. Depending on the weight of the cyclist and the terrain, a single charge can last between 20 and 70 miles.

More important, the experience is much more akin to riding a traditional bicycle than it was in the past. Less than a decade ago, e-bikes struggled with lugubrious handling and motors that would kick in with a jolt. Today’s models are better balanced and use smart algorithms to apply torque gradually, sensing when the rider is putting more pressure into the pedals and then delivering subtle assistance. The latest models even know when they’re stopped and can help the rider get away after a red light quickly.

That adds up to increasing sales. About 400,000 e-bikes are projected to be sold in the United States this year, double last year’s total, according to PeopleForBikes, an advocacy and industry trade group. But that would be just 2.5 percent of the 16 million bikes sold in the country.

Before they can succeed here as much as they have in Europe, e-bikes will have to negotiate a few potholes. Most notably, there is the criticism of throttle e-bikes, which can reach speeds of 28 m.p.h. or more, presenting a danger to pedestrians and other cyclists.