A quick-mount frame structure, particularly for bicycle saddles and similar supports. The structure comprises at least one shell (2) having a top user-supporting surface (6) and a bottom surface (7), said shell (2) having a front portion (8) and a rear portion (9), saddle rails (3) for attachment of said shell (2) to a movable or stationary support, said rails (3) having an outer peripheral edge (10) and means for stable connection between said rails (3) and said shell (2). The connection means include snap engagement means (11) at least at one of said front (8) and rear (9) portions of said shell (2) for quick connection between the shell (2) and the rails (3). A process for making the above structure, and a saddle incorporating such structure.