STATE COLLEGE, PA. ? The first time Rob Gentry saw a friend riding an odd-looking contraption known as a recumbent bike, he laughed. But not for long.

“After I got done making fun of it,” Gentry said, “I found I really liked it.”

It wasn’t just the comfortable ride Gentry liked, but also the panoramic view and the bike’s speed. Now, barely five years after buying his first “bent,” Gentry is not only riding recumbent, he’s doing a brisk businesses selling recumbents — and only recumbents — from his Pennsylvania bike shop.

More and more baby boomers who want to stay physically active are turning to recumbents to ease the strain on their shoulders, arms, backs and knees. As a consequence, sales are rising for these laid-back bikes — known as “bents” to those who ride them.

Not that there’s a recumbent revolution under way. Recumbent specialists estimate that these bikes make up just 1 percent of bicycle sales; Mike Gamstetter, editor-in-chief of Bicycle Retailer & Industry News, said it’s probably slightly less than that.

But even those dedicated to their upright touring bikes say they’re seeing more recumbents on the road.

“It’s definitely been a growing segment of the market, although it’s still pretty small,” said Mike Deme, editor of Adventure Cyclist, the magazine of the Montana-based Adventure Cycling Assn.

Chris and Jane Webb of Cleveland are typical recumbent riders. Chris bought his recumbent when riding upright was no longer comfortable; Jane bought one so they could ride together. The couple and their 13-year-old son, Matt, who rides both recumbent and upright, came to State College in May for a recumbent rally sponsored by Gentry’s shop, Recumbent Bike Riders Inc.

Bob Strosnider, 73, of Winchester, Ky., who also came up for the rally, said prostate trouble aggravated by his bicycle seat almost forced him to give up bicycling. But since buying his RANS Rocket two years ago, Strosnider has been able to ride 60 to 100 miles per week without causing any problem.

Among the benefits of bents:

Jane Webb, left, and her husband, Chris, of Ohio, participate in a recumbent bicycle rally May 23 in State College, Pa. More and more baby boomers who want to stay physically active are turning to recumbents to ease the strain on their shoulders, arms, backs and knees.

l Comfort. With a full-sized seat in a reclined position, the bikes put far less strain on the tailbone. And because the rider isn’t leaning over the handlebars, there is no strain on shoulders, arms, wrists or back.

Rich Pinto, who works in research and development for Florida-based recumbent maker Bacchetta, said that’s why so many middle-age and older riders are attracted to recumbents.

“It’s baby boomers who want to work out, with all of the benefits, but none of the pain,” Pinto said. “Not the butt pain, not the neck pain, not the back pain, not the hand pain. There’s none of it.”

l The view. The rider is reclined with his head up, not leaning over the front of the bike looking down.

“My first reaction was how well you could see,” said Deme, who tried out a recumbent a couple of years ago when his magazine did a special issue on the bikes. “It’s really like riding around in chair. It took a little getting used to, but I liked it.”

l Speed. Because of their aerodynamic design, the rider has a much smaller wind profile — so much smaller that international racing officials banned bents back in 1934.

“They do hold all the speed records,” Deme said. “They just fly downhill.”