Okay kiddo, Keirin is a special type of bicycle racing that started in Japan many years ago.
The way it works is that there are a bunch of bikers that race around a kind of oval-shaped track. But here's the special part – before the race starts, they have a team of people called "pacemakers" ride out in front of the racers to set the speed for the first few laps.
Then, once the pacemakers lead for a bit, the racers start to compete with each other to see who can be the fastest. The winner is the first person who crosses the finish line after a certain number of laps.
Now, Keirin races are very special because they involve a lot of teamwork, strategy, and rules. For example, all the racers have to follow some very strict rules about how they start the race and how they can bump into each other. They also have to wear special helmets and gear to keep them safe while they ride.
So, that’s Keirin. It’s an exciting and unique type of bike racing that involves pacemakers, strategy, and a lot of rules to ensure the safety of the racers.