Motorists have been warned by City Hall and metropolitan police to avoid the route that cyclists will use for Car Free Day on Sunday.
The mass gathering of cyclists will take place at Sanam Luang from 6am.
They will move out of Sanam Luang around 9am, travel along Ratchadamnoen Avenue and reach their final destination at CentralWorld at the Ratchaprasong intersection.
More than 20,000 cyclists are expected to take part in the event.
The cyclists have asked motorists through City Hall and the police to commute by public transport instead of driving private vehicles.
Na Phra That and Na Phra Lan roads will be closed between 6am and midnight.
Phra Chan, Maha Rat and Thai Wang roads will be rearranged as one-way routes during the same period.