A method for making bicycle frames includes a step of preparing initial parts by carbon-fiber sheets and inflatable bladders are inserted into the initial parts which are then arranged to a desired arrangement. The arranged parts are put in a mold which is heated under a certain pressure. The inflatable bladders are inflated by introducing air therein to push the carbon-fiber sheets against the inside of the mold. The carbon-fiber sheets are then solidified to form a front part of the bicycle frame. A rear part of the bicycle frame or the whole bicycle frame can also be made by the same method.