People who ride around the region on red Capital Bikeshare bikes are often smiling folks who are taking part in an urban social experiment in transportation.

So when a man on a Bikeshare cycle punched a pedestrian and snatched her iPhone during daylight hours on a busy Capitol Hill street, it left onlookers shocked.

It happened about 7:30 p.m. Tuesday when the victim was in the 700 block of East Capitol Street SE, talking on her phone.

A man rode up, hit her in the face and pedaled away with the device — all without hitting the brakes.

“She said she was on the phone and was trying to be aware and was holding the phone pretty tight,” said a man who talked to the woman immediately after the robbery but did not see it. “He hit her in the face. He didn’t even stop.”

Alex Fuentes moves bikes to different locations as needed April 22, 2011, moving a couple of bikes from 7th Street NW near the Washington Convention Center. Police say a Bikeshare bike was used in a robbery May 22, 2012. (James A. Parcell/FOR THE WASHINGTON POST)

The victim was not seriously injured, the man said.

Cellphone snatching is fairly common in the District. Using a Bikeshare bike as a getaway vehicle is not: Authorities say they believe this is the first time one of the red rented bikes was used in the commission of a violent crime.

“This is the first report I know of where somebody said they were involved in a crime on a Capital Bikeshare bike,” said John Lisle, spokesman for the D.C. Department of Transportation.

Police put out a generic description of the suspect — a man in his 30s wearing black shorts and a long-sleeve light-blue shirt with a white shirt underneath.

The thief also appears to be tech-savvy. The victim tried to find her phone remotely in the minutes after it was taken, but the thief had already disabled the Find My iPhone program.

Lisle said that crime has generally stayed away from the ubiquitous bikes.

When the program started in August 2008, a handful of bikes were stolen from a station. Since then, a few tires have been slashed and a station or two were vandalized with graffiti, he said.

A Bikeshare bike has not been reported stolen since January.

“Considering the exposure of the system, I’d say it’s extremely rare,” Lisle said. “They’re just sitting out there all hours of the day.”

“It’s curious,” said the man at the scene, who spoke on the condition of anonymity. “Makes you wonder how he got the bike. I don’t know if he put a credit card in and checked it out or has a membership.”

Lisle said that 10 bikes have been reported stolen since the inception of the program but that none was physically taken from another rider.

As for the robbery, the man who talked to the victim said the thief acted fast and zoomed away even faster.

“The scary part is how quickly he can come up and disappear almost without anyone seeing,” he said.