Wow, I have a 25cu bag: On any ride it contains
-spare tube
-Park mini patch kit
-1 Park tire iron (you truely only need one)
-1 workforce mini-multitool (just hex, phillips and slotted - just about everything except for my chain and BB can be adjusted with this tool. I have never had a BB problem, and in over 27 years of serious riding have only broken 1 chain.)
-Old drivers license, Medical Card, Credit Card and $ cash (emergency info is written on my helmet)
-zip lock baggie (keeps things dry)
-cell phone
-house key

-I use a frame pump.