PHOENIX (AP) More and more Arizona bicyclists are putting the metal to the pedal.
In this case, the metal being an add-on gas or electric motor that allows their bikes to reach legal speeds of up to 20 mph on city streets.
Industry experts say its a national trend that is especially evident in Arizona, where riders dont need a license, registration or insurance.
Bicyclists, bike-shop owners, city officials and industry analysts describe an almost underground industry that thrives on word of mouth and Internet searches.
Bike shops and big-box stores also sell powered bikes, parts or installation kits.
In 2011, there were 89,000 premanufactured electric bikes sold in the United States, according to Pike Research, a clean-technology market-research firm in Boulder. That was up from 70,000 the year before. Dave Hurst, a senior analyst at the company, predicts the number will double by 2015.
The total number of e-bikes in the U.S. hit half a million last year, almost triple the 170,000 on the road three years earlier, Pike estimates.
The flurry of powered bikes is fueled by several global trends, experts say. Among them: aging Baby Boomers who want to pedal less; the development of lighter battery packs; cheap manufacturing in China; and affordable shipping. Also, a deep recession and high gas prices have forced a new frugality.
Another factor is growing demand from younger people who cant afford the cost of insuring and maintaining a car and want a cheap means of getting to work or searching for a job.
Some people seek motorized bikes because they have no drivers license, sometimes resulting from drunken-driving penalties.
In Arizona, the heat also prompts riders to motorize their bikes.
Byron LeVan, a pharmaceutical worker in Glendale, got a $150 engine for his bike to save money after he lost his car to his ex-wife. He didnt want to spend $55 a month on a bus pass, a service he considered unreliable.
He was biking, but he suffered heat exhaustion on one summer ride. The motor shaved five minutes off his 20-minute commute.
Powered bikes come in a range of types and prices. The lowest-cost option, powered by a lawnmower engine, can be had for the price of a garage-sale bike and a $180 kit. Premade electric bikes sell for an average of $810, according to Pike, while custom models can cost as much as $30,000.
Customers can save money by buying batteries and installation kits online and doing the work themselves.
Almost all motorized bikes offer the option of pedaling. Some have a clutch that shifts between pedal and automated power. Some gas-powered models can be fitted with boosters, such as nitrogen tanks, to increase their speed.
By federal law, they are considered bicycles as long as they can be pedaled, go slower than 20 mph, and have batteries smaller than 750 watts or engines smaller than 49 cubic centimeters.
In Arizona, that means they can legally travel anywhere a regular bike can, which is everywhere: streets, bike lanes and sidewalks.
A typical gas-powered bike with a half-gallon tank can go 75 miles. A common battery can last 40 miles at high speeds before it needs to be recharged.
Paul Horak, who lives on the Caribbean island of St. Croix, started an Internet forum, motorbicycling.com, four years ago and has seen the number of visitors to the site increase from 10,000 to 45,000 in the last two years. He said the overwhelming majority of them are older than 50.
Its like the fountain of youth for these guys, he said, explaining it gives Baby Boomers a chance to revisit the benefits of bicycling without the pain.
Phillip Robertson, 42, put together an electrified tricycle last year after he suffered serious injuries to his back and hips. He bought the bike for $75 on Craigslist, where he found a battery kit for $300.
It really was a piece of cake, he said of the installation. Anybody who can run a cable and tighten a bolt can do it. I did it in an hour, an hour and a half, Robertson said.
On a recent Wednesday, Robertson pedaled to an Arizona Diamondbacks day game, but normally he rides around his neighborhood in central Phoenix to medical appointments and the store. Its very therapeutic. Instead of `woe is me, staying in the house, this gets me out of that funk, he said.
Experts say that while the trend initially attracted Baby Boomers, the market also is catering now to commuters and younger people.
Horak said hes seeing an increasing number of younger people in his chat rooms. Were seeing more and more kids riding these things to college, he said.
Hurst, of Pike Research, estimates that 80 percent of powered bicyclists ride gas models. Almost all of those are home-built, while half of the e-bikes on the road are manufactured.
The gas models are popular in Arizona, according to a leading vendor of parts and kits based in Southern California.
A lot of our advertising is word of mouth. Its still an underground kind of thing and hasnt exploded yet, said Jeff Lin, who started selling gear online at BikeBerry.com from his warehouse near Anaheim four years ago. Sales this year have climbed 30 percent from last year, he said, adding that Arizona, California and Florida are among his biggest markets.
The popularity and informality of the business prompted him to start a wholesale service a year ago. He noticed customers would start businesses of their own, retrofitting bikes out of their garages, so he offered to sell kits in bulk.
Mike Casto did just that with electric bikes five years ago. What started as a hobby in his garage became Mr. Bs Electrified Bicycles in Surprise and has expanded to Colorado and Texas. Most of his prefab bikes sell for $1,200 to $2,000, and the average age of his clients is 58.
He, too, has seen more buyers as gas prices climb, though analysts say fuel costs dont drive demand.
Every time it spikes, we see more interest, Casto said.
Phoenix traffic engineer Kerry Wilcoxon, who runs the citys bike program, began noticing powered bikes a couple of years ago. Now he sees them a couple of times a week.
Hes worried about the safety implications, but the issue hasnt risen to the attention yet of the police or City Council. Ive seen them on travel lanes, bike lanes and sidewalks, Wilcoxon said.
When powered bikes become numerous enough or there is a bad enough accident, something made more likely by their higher possible speeds, the city may take more notice, he said.