a bracket;

clamping jaws, comprising a first clamping jaw and a second clamping jaw, wherein both the first clamping jaw and the second clamping jaw are pivotally connected to the bracket; and

a telescoping rod assembly, which comprises a telescoping rod set and a gear set, wherein the telescoping rod assembly comprises a telescoping rod and a support rod, wherein the gear set is configured to drive the telescoping rod set to rotate around an axis of the telescoping rod set, and the telescoping rod set is configured to simultaneously drive the first clamping jaw and the second clamping jaw such that the first clamping jaw and the second clamping jaw separately have a first state of simultaneously clamping the two spaced wheels and a second state of simultaneously loosening the two spaced wheels, and wherein the gear set comprises a first bevel gear and a second bevel gear, wherein the support rod is fixedly connected to the first bevel gear, the second bevel gear is meshed with the first bevel gear, and the second bevel gear is rotatably connected to the bracket, and wherein the second bevel gear is configured to rotate around an axis of the second bevel gear so as to drive the first bevel gear to rotate around an axis of the first bevel gear to drive the first clamping jaw and the second clamping jaw to switch between the first state and the second state.