A system for attaching bicycle accessories to the frame of a bicycle is herein disclosed. The system comprises at least two of an upper mount, a lower mount, and a support arm. The upper mount is generally secured to the frame of the bicycle adjacent the junction of the seat post and seat stay of a bicycle frame. The upper mount includes a channel for receiving a first portion of a bicycle accessory. A lower mount generally includes at least one mounting post that extends generally upward from a front or rear dropout of a bicycle frame. The mounting post is adapted to secure a second portion of a bicycle accessory to the frame of the bicycle. The support arm is constructed and arranged to couple a front fork or a seat stay of a bicycle frame to the accessory so as to create a rigid structural relationship between the accessory and the bicycle frame. The attachment system of the present invention may be adapted for attaching accessories to rigid bicycle frames or to bicycle frames that include suspensions. A towing hitch structure may also be included in the system.