Street bikes from Panama. They are called priti baiks. The term priti means both "pretty" and also ingenious, or striking.
The photographs are taken by Jose Castrellon, who spent time hanging around this subculture of hot rodders. Except these guys are too poor to own a car so they soup up their bikes. Note the air horns, normally found on trucks.
His web site says, "Priti Baiks is a series of portraits of men who display tons of creative ingenuity and dedicated a good amount of their meager resources to decorate and equip their humble bicycles."