Wireless communications systems and methods related to frequency resource reservation for sidelink communication over a shared radio frequency band are provided. A first user equipment (UE) senses in a sidelink resource pool within a shared radio frequency band. The first UE reserves, based on the sensing, a frequency resource of the sidelink resource pool within an instance of a variable time range. The first UE performs, in the shared radio frequency band, one or more listen-before-talks (LBTs). The first UE transmits, to a second UE based on the one or more LBTs, a sidelink transmission using the frequency resource within the instance of the variable time range.