"What does a typical chain repair involve, and what else do I need in my bag?" --jmX
Because I don't like the idea of a long walk in cycling shoes; I carry a mini multi tool, spare pin (a master link would really be better), two tire levers, spare tube, patch kit, tweezers or small needle nose pliers, CO2 inflater with a spare cartridge and a mini pump on the frame. Primarily I rely on a thorough check of the bike the night before and inflate tires the day of the ride to prevent the long walk.
Brad