Why do some cyclists refuse to move out of the way and allow cars to pass? (Pete Marovich/Bloomberg News)

Federal officials are continuing to investigate whether to bring additional charges against a white bicyclist accused of assaulting a black motorist in the District. But whether that cyclist is also charged with a hate crime — he allegedly called the motorist the n-word, repeatedly — the rules of the road that set the stage for the conflict will still be on the books.

And what’s on the books is unlikely to make drivers or cyclists happy.

According to D.C. police, the motorist — Kethezo Paho, 34, of Bethesda — was heading west on M Street NW in Georgetown last week when he came upon the bicyclist — Maxim Smith, 24, of Northwest. D.C. police said Paho became angry that Smith was riding slowly and blew his horn to get the cyclist to move over. But Smith apparently stayed his course.

This is a common scenario, and the cause of considerable aggravation for both motorist and cyclist. At issue is a D.C. law that says: “A bicyclist riding on a highway shall not unduly or unnecessarily impede or obstruct traffic.”

Problem is, the meaning of “unduly” and “unnecessarily” seems to depend on whether you are behind a steering wheel or a set of handlebars.

“The law is explicit: A bicyclist can’t intentionally obstruct or interfere with the flow of traffic — but the key is ‘intentionally,’ ” said Greg Billing, executive director of the Washington Area Bicyclist Association.

He noted that the speed limit for most streets in the District is 25 miles an hour and that the average city cyclist is estimated to travel at about 12 miles an hour.

“If a bicyclist is going 10 to 12 miles an hour in a 25 mile an hour zone, that’s not obstruction,” Billing said. “They are just moving a bit slower.”

More like a whole lot slower from where I sit behind a steering wheel.

Driving through Rock Creek Park recently, I came upon a caravan of cars creeping behind a bicyclist who was riding in the middle of the lane. My speedometer fluctuated between zero and 5 miles an hour, stop and go.

Why do some cyclists refuse to move out of the way and allow cars to pass?

One possible answer is that the law doesn’t require them to move over. No more than the law prohibits motorists from hanging out in the left hand lane of a major highway, while traffic backs up for miles. But moving would be the considerate thing to do.

Billing gave a possible reason that I had never heard before.

“Drivers may not understand, but bikers sit up higher and have a better view,” he said. “We can see around corners a little better. So a biker may ride in a way that makes it harder for a driver to pass when it’s not safe.”

The tough love biker, who knew?

“Drivers have so many blind spots,” Billing continued, “and if you let the driver pass on a curve and another car is coming, the passing driver may forget about the biker and slam back into the lane to avoid the oncoming car. Sometimes it may feel like they are intentionally holding back traffic but what they are literally trying to do is keep everybody safe.”

Unfortunately, that’s not how it worked out when Paho tried to pass Smith on M Street. According to police, the cyclist reached out and hit the car. He was charged with destruction of property.

Paho then stopped his car and threatened to call police to report the damage. As Smith tried to pedal away, Paho grabbed the bike. Smith then repeatedly called the driver the racial slur, police said, and struck him in the head with a heavy metal U-shaped bicycle lock.

That’s why prosecutors are trying to determine if Smith should be charged with a hate crime in addition to the other offenses.

Billing condemned both the violence and the offensive language.

“We live in a community that is diverse and we need to respect each other’s differences,” he said. “Violence is not the way to solve a problem, but there were acts of aggression on both sides.”

What had Paho done that struck Billing as aggressive? It was the car horn.

“If a driver is riding besides or behind a cyclist, honking his horn, that’s aggressive,” he said.

Sure enough, D.C. law says: “Do not use your horn to alert a motorist, cyclist or pedestrian of your approach in a non-emergency situation.” The law doesn’t specify what emergency situation would warrant to use of a horn. But the DC Department of Motor Vehicles website advises: “If someone tries to get into your car, attract attention by sounding your horn or a personal alarm.”

In other words, don’t use your horn to warn the wayward cyclist that you are about to pass. Wait until he comes after you with a bicycle lock?

Billing pointed out that it’s against the law for a motorist to pass within three feet of a cyclist. He questioned whether Smith would have been able to reach out and hit the car if Paho had been the required distance away. But cyclists are notorious for passing within inches of a car, especially when rushing to get in front of cars stopped at a red light.

The average traffic lane in the District is about 11 feet wide. The average car is less than six feet wide. All a cyclist needs to do is move over a few feet, and a motorist could pass with plenty of room to spare.

But no.

The law says: “A bicyclist does not have to ride to the far right if the lane is narrow (i.e., 11 feet or less) or if he/she is trying to avoid car doors, pavement hazards, or similar hazardous conditions.”

You have to wonder: With so many convoluted laws and hazardous conditions, maybe bicycles just don’t belong on the streets with cars.

To read previous columns, go to washingtonpost.com/milloy.