Spent a fair bit of time in Bangkok but didn't see very many bicyclists on the roads. Probably due to the traffic and pollution. This maybe a decent ,traffic free option, for those who want to pedal in relative safety. You'll have to deal with jet engine exhaust fumes though.

Bangkok Post article Published: 23 Mar 2014 at 18.54 Online news:

The 23.5-kilometre-long loop at Suvarnabhumi was opened by Airports of Thailand Plc on Sunday to promote cycling. It opens from 6am to 6pm every day. The airport has already become a Mecca for bike lovers. Their favourite location is Suvarnabhumi 3 Road, which is the two-lane road that starts at the intersection of the bus station located to the east of the passenger terminal and runs parallel to the eastern runway for about seven kilometres. But they have to share the road with other vehicles.
With the opening of the bike path, they have a choice of lanes exclusively designed for bikers, which run along the flood-prevention barrier circling the airport.
With a para rubber surface to prevent slips and handle all weather conditions, the green-painted lane is expected to encourage people to enjoy the benefits of exercise by biking,AoT chairman Sqn Ldr Sita Divari said during the launch ceremony.
AoT will consider extending the opening hours after 6pm in the future if the proper lighting equipment is installed, he added.
Caretaker Transport Minister Chadchart Sittipunt, who joined the event on Sunday, jokingly said bikers cannot go back once they get into the lane as it is a one-way traffic.
''Once you head off, you have to go all the way,'' he said in a Facebook posting.