I was asked a while ago what take with me when I ride my road bike. So I laid everything out that I take, less my bike and clothing.
Here’s a list
Seat Bag Contents
1 folding tire
2 inner tubes
1 chain tool
1 quick link
1 spare links of chain
1 presta valve adaptor
1 glueless patches
1 tire lever
1 Mavic hub cone adjusting tool
1 ID card with my name and personal info just in case
And then what I carry in my middle back jersey pocket
1 spare tube
1 pair nitrile gloves
1 glueless patches
1 presta valve adaptor
1 presta valve extender
1 powerbar wrapper to boot a cut tire
1 mini firstaid kit
1 spare cleat screw and washer
$15.00 – $20.00 cash (at the moment I have $19.25)
1 small packet handcleaner
1 park tb2 tire boot
1 multi tool
1 CO2 inflator
4 CO2 cartridges
1 tire lever
1 full bottle hammer gel
1 power bar
1-2 packs of cliff shot bloks
1 cell phone (not pictured)
2 lg bottles water
Now that I have looked at and itemized all this crap it’s time to downsize!

Thats quite the kit you carry!
I typically have just enough to stay out of trouble on my 8 mile commute, and when we go for longer riders i carry everything we need. I learned my lesson after a decimated chain added a 15 mile detour to purchase a whole new one.