High gas prices and growing environmental concerns are making more home buyers interested in bicycle-friendly neighborhoods. Seeing a market, some real-estate agents have traded their suits for spandex and are leading clients from house to house on two wheels instead of four.

While the development is nascent, agents in many areas of the country are offering home tours by bike. Craig Della Penna of Murphys Realtors Inc. in Northampton, Mass., started the service more than a year ago when he realized it would help clients judge whether properties are easily accessible to bike paths. "Because of the bike niche, I have new calls coming in every week," he says. Mr. Della Penna estimates about half of his 18 closings last year came about because he emphasized homes near bike trails.

Cris Noreen, a broker in the Ventnor, N.J., office of Farley and Ferry GMAC, leads clients on bike tours of five homes at a time, riding five to 10 miles per trip. He says some 20% of his sales result from the tours. In Davis, Calif., broker Chad DeMasi got the idea from a client who met him at a showing on a bicycle, telling Mr. DeMasi he wanted to ride around each property's neighborhood to get a sense of how bikeable it was.

While many of these prospective buyers pedal only for recreation -- or view a bike tour simply as a fun alternative to sitting in a broker's car -- others want to cut down on daily driving. The number of people who use bicycles to commute to work grew 28% from 2000 to 2006, when 623,039 Americans said they did so, according to the latest Census Bureau data. The U.S. bicycle industry also has been growing, with sales totaling $5.4 billion in 2007, up from $4.7 billion in 2001, according to research funded by the National Sporting Goods Association.

Targeting the cycling community is a new marketing tool for the struggling real-estate industry. In June, sales of existing homes fell 15.5% from the same month last year, according to the National Association of Realtors. Riding down streets with prospective buyers attracts attention that could result in more business, these agents say. Some Realtors also attend cycling shows and "ride to work" days to boost their client bases.

One recent Saturday, agent Tammee Ryan of ERA Landmark in Bozeman, Mont., was out riding when she got a call from a client, Matt Kemmer. She met him on her bicycle, dressed in Lycra, and apologized profusely. Mr. Kemmer, a 34-year-old software consultant who also is a cyclist, had looked at 25 other properties, but he says he bought the one Ms. Ryan showed in part because they bonded over their interest in cycling and after she pointed out a bike path near the condo. "That's what was important to me," says Mr. Kemmer, who travels extensively for work and likes to ride everywhere when he is home. As a result, Ms. Ryan has started offering bike tours to other clients.

In New York City, Danny Davis, a top producer for Citi Habitats, regularly rolls up to client meetings looking like a bike messenger. Lately, he says, more customers are riding with him. "It's no secret that biking is the most efficient way to apartment hunt in this city," he says.

Pedal to Properties in Boulder, Colo., owns a fleet of bikes. Matt Kolb (left), the company's owner, and Chris Sweeney, its managing broker.

Yet outside urban cores, it can take much longer to see houses by bike, meaning agents usually cover only one neighborhood in a day. There's always the concern that a client could get hurt and the potential for flat tires and broken chains. Bike tours don't make sense in Northern winters, and clients sometimes get caught in the rain. And agents say some clients, particularly those who aren't regular riders, can behave like kids, slamming on the brakes at intersections and ringing the bike bells incessantly.

Matt Peters, a broker with Windermere Dunnigan Realtors in Sacramento, Calif., thought about incorporating his bicycle into his job, but he worries it would diminish his professionalism. Agents in his office wear dressy clothes and drive Lexuses and Mercedes. If he showed up at appointments sweaty, with helmet hair, he says clients might not be impressed, even if they were riding themselves. "It wouldn't play well with my company," he says.

Other agents say showing houses by bike has been a boost. Matt Kolb in Bolder, Colo., started his bike-focused agency, Pedal To Properties, 16 months ago after he saw how much enthusiasm showing houses by bike generated when he was at another agency in town, Benchmark Realty. He now has a fleet of 48 Electra cruiser bikes (upright bikes with coaster brakes that are easy to ride). Every Wednesday evening, he and two other agents from his firm take out four to eight couples to see at least six houses. The clients tend to be in their late 30s and early 40s and include both hard-core bike commuters and weekend riders. After the tour, they go to a restaurant to discuss the houses. Sales at Pedal To Properties have risen 40% over the past year, half of which Mr. Kolb attributes to the bike showings.

It was Mr. Kolb's willingness to go by bike that attracted Kelly Stroker, a 34-year-old research scientist who lived 15 miles outside Boulder and wanted to move closer to town, primarily so she could bike to work. She thought peddling from house to house would be a great way to judge how bike-friendly each home was. One Sunday last month, Ms. Stroker and her husband spent about three hours with Mr. Kolb, seeing seven houses. They eventually chose a $434,000, 2,100-square-foot house less than two miles from Ms. Stroker's job and commutable entirely by bike paths.

Daniel Root for The Wall Street Journal Clients of agent Kirsten Kaufman use bikes to see homes in Portland, Ore.

Cyclists bring their own bikes when they go on Tour de Homes in Portland, Ore., a monthly two-hour outing with Prudential Northwest Properties agent Kirsten Kaufman, who also gives individual bike tours. Last Sunday, Ms. Kaufman arrived on her dark-green Trek, adorned with yellow saddlebags and a "Live Free or Drive" fender sticker, to meet eight home shoppers at a neighborhood coffee shop. She passed out booklets listing the four houses for show, along with a map of their route. As the cyclists followed, Ms. Kaufman pointed out what any agent would (crown moldings, refinished hardwood floors) but also focused on bike-friendly features, like a "tuck-under" garage located beneath the house -- "Wouldn't this be great to just roll your bike out of in the morning?" she said -- and nearby bike-friendly establishments, including a café with ample bike racks and a gallery that makes bicycle bags.

Jessica Engeman and Erik Hovmiller trailed Ms. Kaufman from house to house, removing their biking cleats but wearing their helmets on the house tours. "This is a great way to find a Realtor who understands where we are coming from," Ms. Engeman said. "It's also a totally fun way to spend a Sunday."

The couple, both 30-year-old renters, have been looking for a house for six months, with bike friendliness their No. 1 criterion. A three-bedroom bungalow with original built-ins catches their eyes, but there's a sale pending. "It's OK, because now she has an idea of what we like," said Ms. Engeman, who commutes by bike to her job as a historic preservation specialist.

Write to Nancy Keates at nancy.keates@wsj.com

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