That’s an interesting phrasing for the question.

Typically, when folks are discussing “most popular sports”, it is usually based around attendance or viewership — which we can easily use to quantify the size of the interested audience.

The most popular sport to play is a different question though. A large majority of the fans of every sport are non-participants. Sure, they may have played those games in their youth, but by the time they hit adulthood, work and family responsibilities likely render them as non-participants.

So the most popular sport to play in the world is likely constrained by a few factors:

  • Requires little prior organization and can be done alone or in very small groups
  • Requires a minimal set of equipment and little to no field/court setup
  • Can be played in cities (where a high percentage of people in the world live)

There doesn’t appear to be much data on this (how would you even start to capture it?), but based on the constraints above my best guess is cycling based on these factors:

  1. It’s an activity that people can do alone or in groups
  2. It requires a single apparatus that most people own or have access to
  3. It doubles as a mode of transportation that people use every day
  4. Almost everyone knows how to ride a bike starting as young as 3 or 4
  5. It’s something that you can do for your whole life

Honestly, I can’t imagine that there is another sport that is close to cycling. Thanks for the A2A.