Bicycle trailer

A bicycle trailer for towing by a bicycle which includes a frame body having a seat stay, a chain stay, a rear wheel axle, and a kickstand-mounting piece installed on the frame body adjacent to the rear wheel axle, said bicycle trailer comprising:

• a) an annular carrier frame,
• b) two wheels provided on two side portions of the carrier frame, and
• c) a connecting device which is adapted to be coupled with the frame body of the bicycle,
• d) wherein the carrier frame has a front end portion, a rear end portion, two pairs of vertical stubs extending upward therefrom in such a manner that one pair of the stubs are respectively located on two sides of the front end portion while the other pair of the stubs are respectively located on two sides of the rear end portion, and a pivot seat secured to a lower surface of the front portion of the carrier frame;
• and
• e) the connecting device includes a connecting rod having a rear end section pivoted to the pivot seat in such a manner that the connecting rod can rotate about a horizontal axis, a front end section, and a coupler unit attached on the front end section, the coupler unit including a vertical inner plate adapted to be disposed on one side of the frame body so as to abut against the seat stay and the chain stay of the frame body, and a vertical outer plate adapted to be disposed on a side of the frame body opposite said one side so as to abut against the seat stay and the chain stay, said outer plate being fastened threadedly to the inner plate in such a manner that the outer plate has an inclined upper fastening tab extending toward the inner plate and adapted to abut against the seat stay, a lower fastening tab extending toward the inner plate and adapted to abut against the chain stay, and a positioning stub projecting rearward from a lower end portion of the outer plate and adapted to abut against the kickstand-mounting piece, wherein the inner and outer plates are lockable on the seat stay and the chain stay as to prevent disengagement of the coupler unit from the frame body.