At first it looked like simple bad luck: my cycling buddy John, 20 metres ahead of me on Highway 15 in upstate Vermont, suddenly enveloped in a black plume of diesel exhaust from a passing truck.

I then watched in disbelief as the white pickup advanced to shoot another cloud directly at two other cyclists in our group.

I rode up next to John, incredulous: "Do you think the driver did that on purpose?" We agreed it was hard to dismiss it as a mere coincidence.

Ten minutes later it was my turn. The truck — at least I think it was the same one, but I can't be certain — pulled up beside me and unleashed another black cloud.

At that point I gave the driver my middle finger and yelled words I am not allowed to use on the CBC website. It was probably the exact reaction he was hoping for.

My introduction to 'coal rolling'

As our cycling group of 19 debriefed that evening at our hotel, I learned that several others in the group had also been choked by exhaust from both white and black pickup trucks.

That's when one of the cyclists enlightened me about the anti-environmentalist movement in the U.S. known as "coal rolling."

Drivers spend hundreds or even thousands of dollars to outfit their diesel trucks with a device which, at the flip of a switch, forces extra fuel through the engine, producing a cloud of sooty exhaust.

When emission controls are removed from vehicles, thick black smoke is produced 0:46 It's called "rolling coal," and evolved out of a practice first introduced at truck pull competitions.

Coal rollers pick their targets

Coal rollers seem to chiefly target drivers of hybrid cars such as the Toyota Prius, as well as pedestrians and cyclists, and proudly document their exploits on YouTube.

Some have stated a specific political agenda, "rolling coal" to show their opposition to the emission regulations put in place by the Obama administration.

I was bothered enough by the encounter that I called the local police detachment in Morrisville, Vermont, that evening.

The officer on the desk seemed sceptical. He said a sergeant might call me back, but no one ever did.

Vermont drivers get bad rep

According to Manny Agulnik, who has organized this tour for a couple of decades, Vermont drivers have developed a singularly bad reputation for targeting cyclists, usually by leaning on the horn, but sometimes by passing by as close as they can.

Now it appears some have stepped up their game.

Other than the sooty experience in Vermont, our group enjoyed a fantastic ride through the northeastern states. For the most part the roads had wide, paved shoulders, making it much safer for cyclists there than in the countryside near Ottawa. Drivers were generally courteous, slowing down and giving us a wide berth.

Reporter Steve Fischer enjoying the views and the (usually) clean air of Vermont. (Steve Fischer) One even rolled down his window to say, "I'd rather be biking!"

Racing a pit bull

My only other less-than-courteous encounters were with dogs chained up near the road.

Or at least most were chained up.

As we neared our final destination of Kennebunkport, Maine, what appeared to be a large pit bull came bounding at me from the right.

I shifted my tired legs into overdrive, but the salivating beast gained ground until it was less than a half-metre away — close enough for me to focus on its shiny teeth as it prepared to latch on.

After a few seconds — though they felt like minutes — I managed to outrun the furry monster. My lungs were spent, but at least they weren't full of diesel exhaust.

Thankfully, the rest of the tour was pretty uneventful, and Kennebunkport proved to be a wonderful destination to toast the end our cycling adventure.

We drove back to Ottawa aboard a diesel-guzzling coach bus. Finally, the coal rollers left us alone.