why is world cycle day celebrated ? World Cycle Day: A Celebration of Sustainability, Health, and Entertainment The third of June is World Cycle Day, a day to honour the bicycle and everything it stands for. The bicycle is a simple, inexpensive, and sustainable mode of transportation that is beneficial to both your health and the environment. Here are some ideas for how to celebrate World Cycle Day: Take a bike ride.There's a bike ride out there for everyone, whether you're a beginner or a seasoned cyclist. Lace up your shoes, strap on your helmet, and hit the highway.