NASHVILLE — At a recent convention of Harley-Davidson dealers here, Delia Passi, a marketing consultant, was sharing the finer points of selling to women with her audience of about 150, many of whom wore boots, jeans and tattoos. One wore a T-shirt that read, “Born to Party, Forced to Work.”

Neatly groomed hair is a good start, she said. Always maintain eye contact. Keep those handshakes firm, but not too firm. Clean the bathrooms. Set up a play area for children. And don’t forget the little things that can help draw in passers-by. “Put a plant out there to say you are female-friendly,” she said.

Many of the dealers took notes, and for good reason. American women are the fastest-growing part of the motorcycle business, buying more than 100,000 of them a year. Even though aging baby-boomer men, with money to spend and time on their hands, have played a big role in expanding the market in recent years, motorcycle companies are trying hard to woo women buyers.

“Fifty percent of the population is female and there is pent-up demand,” said James L. Ziemer, Harley-Davidson’s chief executive. “We need to remove barriers.”

So they are producing more motorcycles that are low to the ground — so women can plant their feet firmly at rest — with narrower seats and softer clutches, and adjusting handlebars and windshields to make bikes more comfortable for smaller riders.

They are selling more clothes, too, in bright colors and with rhinestones, rather than the standard-issue black and orange leather jackets. Even the skull motif that appears on some clothing sold at Harley outlets has undergone a friendly makeover to include wings and flowers. Suzuki last year introduced a new line of clothes called Suzuki Girl with tight-fitting riding jackets in pink and baby blue.

Few companies, though, are doing more than Harley in reaching out to this group. Its dealers hold frequent garage parties for women, to let them learn about bikes, including the best way to stand up a 750-pound motorcycle that has tipped over (crouch down, with the small of your back against the seat, and push up and back while holding onto the bike).

The efforts are paying off, though slowly. About 12 percent of all Harley motorcycle sales are to women, roughly 32,000 new bikes in 2006, compared with 4 percent in 1990, 9 percent in 1998 and 10.6 percent in 2003. Women will spend about $300 million on Harley bikes this year in the United States, not including accessories, riding gear and clothes.“I think 12 percent is just the beginning,” said Jerry G. Wilke, Harley-Davidson’s vice president for customer relationships and product planning. “The opportunities to cater to women are endless, and we will continue to do more.”

Harley-Davidson has begun a Web site aimed at women (harley-davidson.com/womenriders) and is advertising in women’s magazines with a striking black-and-white image of a rider using the chrome plating on a bike as a makeup mirror.

Genevieve Schmitt, who runs the Web site womenridersnow.com, said the growth in women bikers reflected that “more women are rising up corporate ladders, women are earning bigger paychecks, more women are remaining single — so they have a say in where their leisure dollars go.” Her site, started in February 2006, now draws 111,000 visitors a month.

According to the Motorcycle Industry Council, the number of women in the country operating motorcycles increased 34 percent to 4.3 million in 2003 (its last owner survey), from 3.2 million 1998. The number for men rose a little more than 20 percent in that period. For all of Harley-Davidson’s new marketing efforts, it lags slightly behind its competitors Kawasaki and Suzuki in percentage of motorcycle sales to women in large part because the Japanese companies offer a wider range of smaller bikes that are less intimidating to many novice female riders.

Robin M. Diedrich, an analyst for Edward Jones who follows Harley-Davidson, predicted that the company would eventually build a less powerful motorcycle specifically for women. “Strategically, I think it is right up their alley,” she said.

Harley-Davidson executives deny they have any such plans, saying women can now operate any of their motorcycles. Company officials say the changes they have made in size and shape of their products will help them win over more women. For years, women bought the Harley Sportster 883 Hugger because it was low to the ground, but many found the ride a bit rough. The company put rubber engine mounts on all of the Sportster models for the 2004 model year to reduce vibration and then replaced the Hugger with the Sportster 883 L the next year. The Sportster 883 L has become a favorite among beginner women riders looking for a low seat and a smooth ride.

Last year the company lowered the Sportster 883 L even more and also introduced the Sportster 1200 L, a low bike for smaller riders who want more power. Before women start considering which model to buy, Harley-Davidson has to stoke their dreams and eliminate their fears. That is what its garage parties are all about.

“This is your baby step,” Jeri Davis, the special event coordinator at the dealership in Grand Prairie, Tex., told a gathering of 50 women recently. “We want you to buy your first Harley-Davidson and not feel it’s your first rodeo.”

The women learned the fundamentals about motorcycles and priced the studded halters and leather jackets. There was a raffle for Texas Ranger baseball tickets, finger sandwiches and plenty of joking among the women, most of whom were middle-aged.

At the end of the two-hour party, many of them said they were ready to take lessons. “I want to get away from the fear,” said Leticia Andrade, a 40-year-old business systems analyst who wore a V-neck Harley-Davidson T-shirt festooned with roses and a butterfly. “My kids are grown and gone, I’m a grandma now, and it’s time for me.”