Abstract: A race horse harness attachment for securing a sulky by its thills to the harness piece about a race horse to limit the pivot of the attachment to rotating about a single horizontal axis whereby the horse may rear without breakage of the thills of the sulky. The attachment includes cup-shaped members extending horizontally from the opposite sides of a base plate and horizontally with the ground into which are detachably-extended inwardly-bent members. These members have an axially adjustable connection with the thills of the sulky to adapt the bridle connection for different size horses. A cotter pin extends through the cup-shaped members for engagement with a groove in the inwardly-bent attaching members to hold the members against axial displacement while permitting their rotation. A substantially rigid connection of the sulky with the bridle is provided wherein rotation is permitted in but one direction rather than in many directions as with ball and socket connections.