BANGKOK -- Thailand's crown prince led thousands of cyclists through the streets of the capital Sunday on a 43-kilometre tribute to his mother, Queen Sirikit, to mark her 83rd birthday.
The high-profile event, carried live by all public television stations, was also an exercise in palace public relations at a time of concern about the royal succession in Thailand.
All roads were closed along the route of what was dubbed "Bike for Mom," which transformed typically traffic-clogged Bangkok, for a day at least, into a biker's paradise. Among the riders were the prime minister, his Cabinet, celebrities and other VIPs. Similar rides took place in provinces nationwide, led by local officials.
"This is a historic event for Thailand," Prime Minister Prayuth Chan-ocha said ahead of the ride.
It was billed as the largest organized bicycle ride ever conducted in Thailand, and Prayuth said authorities hoped to set a world record for a national bike parade. Organizers said that 40,000 people registered for the event in Bangkok and that more than 250,000 registered for rides held across the country.
"The event will also showcase to the world how devoted Thais are to their queen," Prayuth said.
Thailand's revered monarch, 87-year-old King Bhumibol Adulyadej, and his wife, Queen Sirikit, are both in declining health and have been absent from public life for years. Their only son and the heir apparent, Crown Prince Vajiralongkorn, does not command the same respect and affection as his father, though open discussion of the monarchy is constrained by a strict lese majeste law that makes criticism of the royal family punishable by up to 15 years in prison.
Mostly seen at formal ceremonies, the 62-year-old heir to the throne rarely mingles with the public.
But Sunday's bike ride was an apparent effort to rehabilitate his image. The crown prince shed his tailored suit for black bike tights topped with the event's light blue "Bike for Mom" T-shirt as he blended with other bikers in a band of blue through Bangkok's streets.
"It's him! It's him!" shouted an onlooker at the city's Victory Monument, as the prince pedaled past. The event started at Royal Plaza, in the city's western historic quarter, and followed a circuit northward as thousands of people in blue shirts watched from the sidewalks. Some waved Thai flags or held pictures of the royal family.
In Buddhist tradition, blue represents Friday, the day of the week Sirikit was born. It has become the colour associated with the queen in predominantly Buddhist Thailand, while yellow -- which represents Monday -- is the colour worn to honour the king.
Sunday's event took place a few days after the queen's Aug. 12 birthday, which is also a national holiday and celebrated as Mother's Day in Thailand.
Last week, the palace announced its latest update on the king's health, saying he was recovering from several ailments, including excess fluid in the brain and difficult breathing due to congested lungs. Last October, he had his gallbladder removed.
The king has rarely left a Bangkok hospital that has become his residence since he was admitted in 2009 with what was said to be a lung inflammation. The queen has also seldom been seen in public since suffering stroke-like symptoms in 2012.
Most Thais hold great affection for Bhumibol, who took the throne in 1946 and is the world's longest-reigning monarch.
Associated Press writers Penny Yi Wang and Nattasuda Anusonadisai contributed to this report.
