This is a worldclass lane running around the airport. You will need to register to enter (bring your passport the first time). Access is free. Many options for food, drinks, bikeshops and rentals. Go early cause it gets very warms already at around 9 am
Nice 23km+ track around Suvarnabhumi Airport. Crowded in the morning from 6:00, and in the evening from 16:00, but there’s no shade, so it gets hot. Infrastructure are great. There’s a bike shop where you can get you bike cleaned and fixed, buy all necessary gears, a 7/11, cafes, food, fresh juice and everything you can dram of. Can even take a shower upstairs 🙌