A bicycle derailleur mounting structure includes a base member (26) and a stopper (36). The base member (26) includes a first portion (32) configured for attachment to a bicycle frame (14). The first portion (32) of the base member has a first side surface (40) and a second side surface (42) with an aperture (44) extending between the first and second side surfaces. The stopper (36) is coupled to the base member (26) between the first and second side surfaces. The stopper is configured for setting an angular position of the base member relative to the bicycle frame.