Abstract: An adjustable bicycle brake comprises two brake arms, two brake shoes fastened respectively with the brake arms, and one tension spring. The brake arms are fastened pivotally and symmetrically with a bicycle frame and are provided respectively with a stopping block. The tension spring is fastened at both ends thereof with the brake arms and is provided with two pushing blocks urging the stopping blocks of the brake arms. The pushing blocks can be displaced to bring about the displacements of the brake arms so as to adjust the brake shoes to be separated equidistantly from the bicycle wheel.