Police arrested a number of cyclists near the Olympic Park in east London as the opening ceremony was under way in the main stadium on Friday.
Officers surrounded a group of up to 100 cyclists on a road to the east of the Park who had been taking part in a monthly alternative "Critical Mass" ride around London.
As the ceremony drew to a close police were putting the cyclists on buses and taking them away from the area.
There was little tension evident and officers were seen chatting and joking with the detained cyclists.
"It was very good humoured, but the police were very jittery," one female rider, who had avoided the police cordon, told a Reuters reporter at the scene.
London's Metropolitan Police had told the riders to stay well away from the Olympic events and conduct their ride in south London.
"We are aware of a number of people in breach of conditions imposed on the cycling event under section 12 of the Public Order Act", the police spokesman said.
There was no immediate information on the number of arrests, the spokesman added.