A black cyclist claims he was "harassed and humiliated" in public by police officers who stopped and searched him for "smelling of marijuana".
Mani Arthur, the founder of Black Cyclists Network, claims after the Met Police officers found nothing on him they said they could no longer smell the drug.
He said he was cycling through central London when they initially questioned him over the position of his bike in the road as he waited for a red light to change.
After that, they put him through the "degrading and humiliating experience" of being searched on the side of the road.
Footage posted on Instagram shows Mr Arthur, dressed in cycling clothes and a helmet, removing his shoes while being patted down by a gloved officer.
The officer says he is satisfied that he Mr Arthur does not have any cannabis, and adds that he cannot smell the drug "at the moment".
A Met Police spokesman said the force has not received a formal complaint about the incident, which happened at the junction between Woburn Place and Euston Road, but is aware of it.
The Instagram post said: "I was detained and searched by a police officer under the suspicion of "smelling" of marijuana. I was harassed and humiliated in a public space."
He added: "In short, I was waiting in traffic for a green light. Three police officers were crossing the road.
"The one in the video told me to reverse my bicycle back behind the white line were vehicles have to stop. I was not blocking the pedestrian crossing.
"I told the officer that I would be putting myself in danger if I reversed because a small HGV was sitting directly behind me and I would end up in the driver's blind spot if I followed his instructions.
"The officer tried again but I resisted and he turned around to join his colleagues as they were walking away. The lights changed to green.
"I was riding off to join Aaron and Hugo, who by that point were in the middle of the junction when I heard a call from the officer to turn back."
Mr Arthur added that the police officer asked for identification and announced they could smell cannabis. He said he was then searched.
The post added: "After the search. They conveniently said they did not smell cannabis on me.
"I am very annoyed at having to go through such a degrading and humiliating experience.
"It seemed to me like a gross abuse of power by an officer who tried to show off to his colleagues and made up a reason as retribution for his failed attempt."
The Metropolitan Police said in a statement: "We are aware of a video showing a Roads and Transport Police Officer carrying out a stop and search involving a male cyclist."
Detective Superintendent Andy Cox, of the Roads and Transport Policing Command, added: “While no formal complaint has been received about the incident we have spoken to the officer involved to establish the exact circumstances and so any learning identified can be implemented.
“We will also endeavour to make contact with the cyclist involved to get their views.
“Metropolitan Police officers carry out hundreds of interactions with people throughout London every day and we welcome the fact that their actions are scrutinised so, where appropriate, they can be held to account.”
