"I was just, like, this is insane. I'm not sure if this is going to get ugly," said cyclist Dirk Friel. "He was definitely the one who could do more damage to us than us to him."
The cyclists used their smartphones to film the ordeal.
"This is getting old," one of the cyclists can be heard saying on the video.
The two-lane road had no shoulder, but the cyclists are seen riding on the far right line.
"What's even worse is we saw him approaching from behind and to be polite, we ride single file to give him as much road as possible, as we did with every other car we encountered on this road," one of the cyclists wrote on YouTube. "This guy was so intent of bugging us that he backed up traffic behind him and cars had to pass him on a double yellow line."
The cyclists said they eventually slowed down to force the driver to pass them.
After Friel posted the video, another cyclist commented that he had had a similar incident with a person he believed to be the same man a few weeks ago.
Scripps station KMGH tracked the license plate number to a home in Erie, but the driver’s son, David Ernst, said his 76-year-old father was not home.
"I don’t know what happened," he said. "Maybe there was something that precipitated it. I don’t know, because he’s a gentle old man."
A 2009 Colorado law allows drivers to cross a yellow line to pass cyclists if it is clear.
"Under Colorado law, bicycles are vehicles just like a car or truck or motorcycle," said Dan Grunig of Bicycle Colorado. "So we have the same rights and the same rules to follow" as other vehicles.
Colorado State Patrol said troopers are interviewing witnesses and the cyclists to decide if charges should be filed.