The invention is applicable to the field of bicycle accessories, and particularly relates to a riding-purpose strap mainly applied to pedal plates of a fixie bike and a rider of the fixie bike. The riding-purpose strap comprises a main strap body installed on a pedal plate of the bike and used for constraining a foot, an auxiliary strap body detachably installed on the main strap body and used for pushing the foot out of the main strap body, a sensor unit used for detecting the speed of the bike, a control unit used for controlling the auxiliary strap body and the sensor unit to work automatically, and a steel hoop used for being matched with the auxiliary strap body to serve as a bike foot strap. Due to design of themain strap body, the auxiliary strap body and the steel hoop, when stopping riding the bike, the rider can easily pull the foot out of the main strap body, the possibility of falling-off caused by excessive tightness between the foot and the strap is reduced, the strap and the foot strap can be switched quite fast, and the riding-purpose strap can further be used as a trouser belt.