Drill string components having multiple-thread joints

Drill string components having a plurality of threads extending around a body. A first end of body can define first and second cylindrical shoulders that are spaced apart relative to a central axis of the body, and at least two threads can extend between the first and second cylindrical shoulders. The first and second cylindrical shoulders have respective cylindrical inner and outer surfaces. Optionally, each thread can have a thread root, a thread crest, and a pressure flank surface extending radially from the thread root to the thread crest and defining a pressure flank angle relative to a plane perpendicular to the central axis. Optionally, the thread crest of at least one thread can circumscribe a frusta-conical surface extending over at least a portion of the axial length of the plurality of helical turns of the thread.