noun
keirin; Japanese track cycling race
A professional cycling event, typically 2 km, with a paced start behind a motorized pacer and a sprint finish. 競輪 is common in gambling contexts; ケイリン is often used for the sport itself.
彼は競輪で大金を稼いだ。
He made a fortune on keirin betting.
ケイリンはオリンピックの正式種目になった。
Keirin became an official Olympic event.