100 max on my fixed, a century XD; more on my roadie

As mentioned above and aside from those mentioned by OP, cash, debit card, multitool, tire levers, tire bead jack, patchkit, swiss army knife, smartphone (seriously 2 UP's a regular cellphone considering you have internet), handkerchief, clif bar, first aid kit consisting of bandages, alcohol wipes, and neosporin.

All in a large/ extra large saddle bag.

Dress is also important; wearing street clothes would be torture... lycra is the way to go, and gloves as blisters could build up especially on long runs, and they suck. Did I mention they suck?
Safety as well; wear a helmet!

Prep is important aswell; stretch, warm up, and hydrate and nourish yourself beforehand.