Spare tube, repair kit, tyre levers, small adjustable wrench, dumbbell spanner, couple of allen keys, chain tool, pump (frame pump or mini). Unfortunately, the only time I've had a breakdown recently was a broken rear mech hanger and a mangled chain and there wasn't much I could do about that. Fortunately I was only about five miles from home and walked back (coasting on the downhills). Had I been further away I'd probably have tried to fix up a single-speed arrangement. How often do I ride? I average about once a week, purely for pleasure - commuting is out, as I work at home.