There is a total of 7 Red Ducks in Dying Light 2 which you can find in safes located in and around Villedor. Once you have the 7 red ducks you'll be able to get the secret bicycle.
Bicycle Parkour Challenge
Once you have all 7 red ducks, go to the area near VNC Tower Metro and find a bicycle. It's outside of the metro station, leaning against one of the supports of a nearby skyscraper. Interact with the bicycle and a parkour challenge will begin. During this challenge, you must use one of the bikes standing near the first checkpoint and ride it to the top of the skyscraper.
