Greg Cantori has been using his man-powered velomobile to commute from Pasadena into Baltimore. A bicyclist who commuted to work for years, he switched to the faster velomobile last year. (Christopher T. Assaf/Baltimore Sun video)

Greg Cantori has been stopped by police five times in recent months.

The officers have all asked him the same question: What the heck are you riding?

Each morning, Cantori steps into a vehicle resembling a yellow submarine and pedals the 24 miles from his Pasadena home to his Hampden office.

Called a velomobile, it's one part tricycle, one part Wienermobile and entirely pedal-powered. It's also incredibly fast because of an aerodynamic shape — one officer who pulled over Cantori at the base of a hill clocked him at 50 miles per hour.

Cantori, the president and CEO of Maryland Nonprofits, enjoys commuting by velomobile for the same reasons he rode his bike to work for decades. He feels the heat of the downtown streets, smells the green freshness of the woods along the Jones Falls. He waves at crossing guards he has passed each day for years.

"There's a sense of freedom you don't have in other modes of transportation," he says. "There's a happiness effect."

All those hours on the bike keep Cantori in top form. At 54, his resting heart rate is that of an athletic man less than half his age.

"I call it my workout to work," he says. "I hate driving to work, not only because of the traffic, but because I didn't get my workout in. When I ride the bike, I get both."

Although Cantori has only owned the velomobile since October, he has been biking to work for three decades. Over the years, he has seen an exponential increase of people commuting by bike.

"Now I'm seeing dozens and dozens," of commuting cyclists each day, Cantori says. "We give each other little waves. We know we're doing something a little unique, but something that is right for us, for the environment, and frankly, for our pocketbooks."

Cycling commuters will find rallies, giveaways and snacks along their routes Friday as the state hosts the annual "Bike to Work Day." Events, which were rescheduled after an earlier date was rained out, are planned for Baltimore, Annapolis and Columbia, among other locations.

Baltimore has made strides in recent years toward becoming more welcoming to bicyclists, advocates say. The city was recently recognized as being bicycle friendly by the League of American Bicyclists.

The miles of bike lanes in the city have increased eightfold since 2006, to more than 180 miles. Four new bike shops have opened, and some 1,500 riders come out for the Baltimore Bike Party, a monthly ride and gathering. A September census counted 3,000 bicyclists at four locations on a single day, a 65 percent increase from 2010.

These improvements, coupled with a growing interest in cycling nationally, have prompted more people to commute by bike, says Mary Herbranson, development director of the advocacy group Bike Maryland.

"Once you get used to adding a bike to your routine, bringing a second outfit and biking at a speed suitable for your activity level, you can save a lot of time that you would have normally spent at the gym or going for a run after work," she says.

Cantori has long been an advocate for human-powered transportation. He's the former president of Bike Maryland, back when it was known as One Less Car.

He gets some strange looks when he rides in the velomobile, which, according to a database of owners, is one of only 250 in the United States. Motorists often lean out of their cars to snap pictures as he pedals by.

He begins his 25-mile ride to work around 6 each morning. The journey from his home near Fort Smallwood Park takes him across three bridges, up Calvert Street and then along a winding, leafy stretch of Falls Road. The ride usually takes 45 minutes to an hour, depending on the weather, traffic and how Cantori is feeling. He usually keeps the cover open, convertible-style, unless it's raining hard.

He has been traveling by bicycle nearly his entire life. He pedaled from his Southwest Baltimore home to classes at University of Maryland, Baltimore County in the 1980s, back when most bike riders were kids. He kept it up when he started working. For many years, he pedaled between his Pasadena home and his former job at the Marion I. & Henry J. Knott Foundation, also in Hampden.

Cantori touts the environmental and economic benefits of bike riding. Those who eschew cars not only avoid pumping exhaust into the air, but also save on gas, insurance and car maintenance. So while it may take longer to travel a mile by bike than by car, it also takes you much longer to earn the money to pay for that car.