When Josh Hartman starts pedaling, it's nearly impossible to keep up with him.

"I just love being competitive," Hartman says. "I just love feeling so free on my bike. I feel like I can make a difference in the world."

The 21-year-old is one of the fastest cyclists in the world, able to accelerate from 0 to 40 in just 18 seconds. He's so fast, he has a good shot at making the 2020 Olympic team.

Hartman's journey is an unlikely one. Cycling is not a popular sport in East New York, Brooklyn, where he grew up after emigrating from Guyana when he was eight years old.

But when Hartman was 11, he knew he wanted to try it out, inspired by his cousin, Randolph Touissant, who competed in the 1984 Olympics for Guyana.

"From day one I knew what the goal was," Hartman says. "And that was to be an Olympian just like my cousin."

Soon, Hartman was training daily, both at Prospect Park and at the Kissena Velodrome in Queens, the region's only banked, Olympic-style cycling track.

At Kissena, he trained with a program called Star Track, which exposes city kids to a sport associated with people of means from suburbia.

"We like to bring kids from the under-resourced areas out and introduce them to the sport," says Pete Taylor, a Star Track coach. "It's great for self-confidence, for fitness, for team-building."

Hartman soon started winning awards, so many he can't keep track.

"I just have them hanging out at this point," Hartman says. "I have so many," he adds with a laugh.

But it all nearly ended during a race in Brooklyn six years ago, when he turned a corner too fast and smashed into a barricade head-first. Hartman's face shattered, his lungs collapsed and he ended up in a coma for two weeks. Scars from that day are still visible on his face.

"It keeps me going at times when I don't want to keep going," Hartman says. "On the hard days, I go in front of the mirror and I look at myself, and it's like, you sacrificed so much - the pain and everything you've been through - like, you can't give up now."

Hartman could not ride again for more than a year.

But he was determined to return to his former glory.

He won his first race back.

And for the last 2 and 1/2 years he's been training six days a week at the U.S. Olympic Center in Colorado Springs - the only African-American cyclist there.

"Only myself," Hartman says.

Hartman wants to compete in the next three Olympics -- and then call it quits.

"I want to retire by the time I’m 30," Hartman said.

From there, he wants to mentor children, which he's already doing now through Star Track, and then start some companies, including a fashion line.

"I got everything mapped out and planned," Hartman says.

Traveling life at top speed, just like he does around the track.