1. stuff to change a flat tire
tire levers
extra tubes
frame pump
2. Ulock if you're going to lock up
3. lights if riding at night.
4. multitool
everything else is optional, IMO.
__________________
"Think of bicycles as rideable art that can just about save the world". ~Grant Petersen
Cyclists fare best when they recognize that there are times when acting vehicularly is not the best practice, and are flexible enough to do what is necessary as the situation warrants.--Me