(CNN) -- Keith Felch is admittedly a big guy, but more than a few super-fit cyclists in Southern California have been left wondering how that dude just went flying by.



Keith Felch calls his electric bike a "hill eraser" because he can ride it to work without breaking a sweat.



And then his wife, Mary, comes motoring past.



"They stare, like how can a girl go past me," she says, laughing. It takes the other riders a few seconds but then they figure it out.



They have electric motors.



The Felches, who live in Aliso Viejo, California, used to drive everywhere, except when they used their bikes for recreation.



That changed when they got their new e-bikes, made by a company called Optibike. Now, they ride to go shopping and to go to breakfast -- but mostly they ride to work.



Keith Felch says the couple has cut 50 percent of their car-use since they started electric biking.



And there are other benefits. Keith Felch dropped 30 pounds and his blood pressure fell 10 points in the first six months he owned the bike, he says.



The Felches don't exactly classify themselves as "environmentalists," although Mary said it is important to have a positive effect on the planet.



"I learned that the worst amount of smog that you put out [in an automobile] is in the first mile, so if we can make even some of those shorter trips on our bicycles, it makes a big difference," she says.



Who wants one?



Brent Meyers, director of sales for Ultra Motor US, says electric bikes attract different types of buyers.



Many are looking to make a green imprint.



Some are "active adults" who have ridden bicycles for years who -- as they get older -- are unable to do the same kind of riding they did when they were young.



Other buyers want to ride their bikes to work quickly -- and avoid a sweaty entrance into the office.



Oddly -- or perhaps not -- Ultra Motor US sees its strongest sales when the price of oil skyrockets, says Meyers.



Two wheels, a motor and 100 million riders



Electric bikes are still somewhat of a novelty in the United States, but in China they're everywhere.



In fact, Chinese electric bikes number more than 100 million -- which is about four times the number of Chinese private cars, according to Electric Bikes Worldwide Reports. The bikes are popular in Europe as well.



Sales figures for the United States are hard to pinpoint.



In the United States, about 200,000 electric bicycles were sold last year, said Ed Benjamin of the Light Electric Vehicle Association -- about twice the number sold in 2005.



But the industry has hit a bump in the road from the recession, as sales were down about 10 percent in 2009, he said.



E-bikes are mostly made by specialty companies, but the growing sales trend has been noticed by the big boys.



Trek, a worldwide leader in bike sales, has been making electric bikes for three years, but only introduced them in the United States in the past year.



Other well-known companies like Schwinn and Giant are increasing their presence in the e-bike field.



At Interbike, the biggest bicycle industry convention in the United States, there were more than 20 companies displaying e-bikes this year. Meyers said only a few years ago, it was about five.



Prices range from a few hundred dollars -- the E-Zip Trailz Hybrid costs $398 at Wal-Mart -- to more than $13,000 for OptiBike's top-end model.



Prices increase as battery technology and components get better.



Steve Roseman of The Electric Bike Network in San Francisco, California, said most buyers he sees don't balk at the price, which can be as much as a good road or mountain bike. They are mostly concerned with how far they can go on a battery charge and how fast.



What's an 'e-bike
How many electric bikes does  china have? How many electric bikes are in China? What can electric bikes run on? How many more bikes than cars does China have?
more than 100 million more than 100 million motors. four times
question: How many electric bikes does  china have?, answer: more than 100 million | question: How many electric bikes are in China?, answer: more than 100 million | question: What can electric bikes run on?, answer: motors. | question: How many more bikes than cars does China have?, answer: four times