The invention relates generally to disulfide drug conjugates wherein a linker comprising a sulfur-bearing carbon atom substituted with at least one hydrocarbyl or substituted hydrocarbyl is conjugated by a disulfide bond to a cysteine sulfur atom of a targeting carrier, and wherein the linker is further conjugated to a drug moiety. The invention further relates to activated linker-drug conjugates suitable for conjugation to a targeting carrier by a disulfide bond. The invention further relates to methods for preparing hindered disulfide drug conjugates.