A bottom frame of a bicycle hanger includes a main body having a straight pipe for being sleeved onto a vertical rod, a stopper attached to the bottom end of the straight pipe for preventing the vertical rod from extending out from the bottom end of the straight pipe, a connecting unit attached to the straight pipe, and three legs attached to the connecting unit. At least two of the three legs are pivotably attached to the connecting unit for being unfolded or folded. Each of the at least two pivotable legs has a positioning structure. The positioning structures provide positioning effect to the at least two pivotable legs. The three legs extend from the connecting unit outwardly and downwardly to a position below the bottom end of the straight pipe for being abutted on a ground.