Thai citizens in more than 70 countries are expected to join their compatriots in Thailand to bike ride for His Majesty the King on Dec 11.
The "Bike for Dad" campaign was officially launched on Wednesday at Government House with a plan set out by the organisers.
Prime Minister Prayut Chan-o-cha said after the meeting to prepare for the event that the organisers expected Thais living in 70 countries to take part in the occasion held to celebrate the King's 88th birthday which falls on Dec 5.
The cycle ride will begin in Thailand at 3pm with His Royal Highness Crown Prince Maha Vajiralongkorn leading all riders on a 29-kilometre loop. Other provinces will start the event at the same time on routes passing key religious and other important places in their neighbourhoods.
Other countries will hold the cycling event between 9am and midnight depending on their location.
The website www.bikefordad2015.com will be opened from Nov 2-15 for registration, and a call centre 1122 will be set up for queries from bikers.
Gen Prayut said Dec 11, which is on Friday, will not be a public holiday and traffic plans will be mapped out to prevent congestion on that day.