JEFFERSON PARISH — Sure it's hard to take on powerful oil companies operating in the Gulf, but that wasn't stopping Frazer O'Hara, when he took his anti-petroleum message on the road.

When I came across him on Friday, he was about 30 miles into his journey, cycling south on Interstate 310 heading into the bayou. It was midday, and hot even by local standards — a soupy 90-plus degrees.

On the back of his white shirt in large hand-painted letters, it said, "Bicycles prevent oil spills."

In a roadside chat, with semi-trucks roaring past, a sweat-drenched but cheerful O'Hara explained his mission: "I'm just trying to take over the right hand lane as much as possible with the message that we could prevent this kind of (oil spill) disaster," by putting the brakes on oil consumption. "That it's our choice."

The 29-year-old Loyola University grad said he had set out in the morning from Jefferson parish, next to New Orleans, bound for Grand Isle, a barrier island at the edge of the bayou, a journey of just over 100 miles.

Was it legal to bike down the Interstate? No, he said, but so far the police had not taken an interest. That changed moments later when state trooper Johnny Champagne pulled up on the shoulder.

Photo by Kari Huus/msnbc.com

O'Hara rides south on I-310, on a journey to Grand Isle, La. His shirt reads: "Bikes prevent oil spills."

O'Hara was ready with his rationale, his message about oil, and he quickly pointed out that as a taxpayer he had helped pay for the road.

Champagne noted that indeed, it is not legal to bike on the Interstate, but he didn't press the issue nor pursue philosophical discussion.

"Just making sure everything was okay," he said after assessing the situation. After the trooper left, O'Hara explained that he was also working with a non-profit called Team Gulf, an Internet-connected activist group that turned its focus to helping in the Gulf after the Deepwater Horizon accident.

Corporate interests are powerful and daunting, said O'Hara, so people needed to band together to be influential.

"The only thing we can do is amass the strength we have in numbers." For the day, though, he was a one-man demonstration, with many hours on the road ahead to get his message out.