Old English ridan "sit or be carried on" (as on horseback), "move forward; rock; float, sail" (class I strong verb; past tense rad, past participle riden), from Proto-Germanic *ridanan (cf. Old Norse riða, Old Saxon ridan, Old Frisian rida "to ride," Middle Dutch riden, Dutch rijden, Old High Germn ritan, German reiten), from PIE *reidh- "to ride" (cf. Old Irish riadaim "I travel," Old Gaulish reda "chariot").
Meaning "heckle" is from 1912; that of "have sex with (a woman)" is from mid-13c.; that of "dominate cruelly" is from 1580s. To ride out "endure (a storm, etc.) without great damage" is from 1520s. To ride shotgun is 1963, from Old West stagecoach custom in the movies. To ride shank's mare "walk" is from 1846 (see shank (n.)).