What is in your bike's saddlebag?

 All seasoned cyclists have an equipment pouch with them when they ride. Most often it's hanging below the saddle (saddlebag), sometimes it's attached to the stem and the top tube (bento bag), or in a triangular pouch between the top tube and the down tube, or in the second water bottle (usually the one on the seat tube), or in the Camelbak backpack. However we are carrying the equipment/tools, we are carrying them. They are the safety net that allows us to ride far away from home knowing that we will probably be able to cope with any roadside mechanical and ride back home (or at least to the working bus stop or within Uber/Lyft/Taxi range). 

The most common mechanical problem you will get on the road/trail, of course, is the flat tire. Being able to change flats properly on your own is a necessary skills for any cyclist. Check with your local bike shops or cycling clubs to see if there is any flat clinic available (they are usually free). If not, there are several good 'how to' videos on Youtube. I recommend the Park Tool videos. They are really excellent and thorough. 

So, what is in the bag?

At the minimum, your saddlebag should contain:

A spare inner tube that fits your tires and wheels, a patch kit, CO2 nozzle and a couple of canisters unless you are carrying a frame pump, tire levers/irons, a multi-tool with a chain-tool and spoke key(s) that fits your spoke nipples. 

If you ride your bike enough, you WILL have a mechanical issue on the road sometimes. Even if you don't know how to repair whatever it is, it's best to have the tools with you. Chances are a good Samaritan will stop to check on you (cyclists are pretty good that way), but he/she won't be able to fix it for you if there is no tool available. 

My saddlebag's contents.

I ride solo in lonely places far away from help a lot, so my saddlebag isn't quite 'minimalistic'. There are:

• Powdered spare inner tube. My tubes come unpowdered in a paperbox. I take them out of the box, powder them, and wrap them each in a plastic bag with a 16 or 20 g canister of CO2, and write the tube's spec on the bag (since I switch between 28mm and 30mm tires quite a bit, depending on what sort of terrain I was heading into).
• CO2 nozzle and at least 2 CO2 canisters of 16 or 20g. I use the super easy to use basic green Genuine Innovations G20315 nozzle. They're very hardy and small. 
• Two tire levers (plus one more attached to the multi-tool). 
• A preglued patch kit (with 5 patches in it). 
• A Park Tool IB-3 multi-tool with chain tool, spoke keys, and the extra tire lever. It's a heavier multi-tool, but it is super sturdy and has nearly all the tools you'd need. 
• A missing link. Well, usually 2 of those, one standard one, and one Wipperman Connex. The Wipperman is missing in the photo, since I used it the day before to connect a riding buddy's broken chain on the road. Unlike the standard missing link, the Wipperman Connex link can be used multiple times, and does not require any tool to install or remove. It is quite a bit more expensive than the standard missing link, but it's worth every penny.
• A mini lube pouch.
• Alcohol pads (for cleaning disc brake rotors or the braking surface on wheel rim).
• A Schrader/Presta valve adapter, so I can make use of gas station air pump. Gas station air pumps generally max out at 80 psi, which is not ideal for many. But I'm light enough and running bigger tires, so 80 psi will easily enable me to ride home.
• A nitrile glove and wet wipe. I look scary enough on my own without the involuntary post-repair black face paint.
• A tablet of Diphenhydramine antihistamine (aka Benadryl)... you never know when you're gonna run into an angry bee or rattler. 
• A sock (you know how they get unpaired in the laudry and all of the sudden you have a closet full of unmatched socks?) and a spare rubber band. I also wrap a length of electrical tape around my handlebar stem, just in case. Just about everything but the tire levers go into the sock, and then into the saddlebag. It helps to not loose the little bitty stuff on the ground. Besides, it's a handy chain-wipe when needed. 
• An extra strap. Or a zip tie. 
• A piece of candy... Of course, I also carry gels and stuff in my jersey pocket. It's a just-in-case candy. Sometimes you get sort of frustrated wrestling with Murphy's Law's Revenge Days, and just need a pleasant sweet things to cheer you up a bit. I'm not called Smorg for nothing!