Four people have been charged with various offences during Friday night's protest, while the rest were released pending further questioning, Scotland Yard said.
Police said that they were aware that a monthly protest by cyclists was planned for Friday but ordered the protesters to remain south of the River Thames. That was to keep them from blocking more than 80,000 ticket-holding guests from attending the Olympics opening ceremony.
Police said around 400 to 500 people gathered for the demonstration attempted to cross the Thames to the Stratford area, where the Olympic Park is located, defying police warnings and attempts to stop them. The cyclists split into small groups and some managed to reach Stratford.
In a statement, Metropolitan Police said it respected the right to protest but officers must stop protesters who affect athletes, spectators, and ordinary Londoners. It said officers began arresting the cyclists only after they ignored verbal warnings to leave the area.
The anti-capitalist group Occupy London, part of a global movement that has waged demonstrations against financial institutions and capitalist policies, said some cyclists were members of their organization. They said police cordoned off more than 100 cyclists at one road junction near the stadium as Friday's ceremony was beginning and held them there several hours.