If you ride a bike, you're going to get a flat. Seriously, it's going to happen eventually. You hear a funny noise... stop... look down and... dang it... flat tire.
At that point, your options are: walk home, call a ride, or fix your flat.
The third option is by far the fastest, but it means being prepared. Thankfully, you don’t need to carry much to be ready for the most common on-the-go repairs.
Spare Tube
The first thing you’ll need is a spare tube. Make sure you have the correct size and that the stem is long enough for your rims. The stem will have either a Presta or Schrader valve. Learn the difference and make sure your valve type matches your pump. If you want to save some weight, consider a latex tube like Schwalbe’s Aerothan tube. They are just as tough, if not tougher, than butyl tubes but they weigh less and roll up much smaller. If you have your bike set up tubeless, it’s still a good idea to have a spare tube. Don’t forget to carry some extra sealant as well in case too much comes out during the puncture-sealing process.
Tire Lever
To change the tube, you’re going to need to get the tire off the rims, which requires a tire lever (or very strong thumbs). One tire lever is generally enough, but two is even better if your tires clinch tightly to the rims.
Pump
Inflating the tube will require either a pump or a CO2 cartridge system. Pumps are more eco-friendly as you don’t have the empty cartridges to dispose of afterward. Just make sure you get a pump that matches your needs of high pressure for a road bike or high volume for a gravel or mountain bike. Otherwise, you’ll be pumping forever and never get enough air in your tube. Many pumps also come with a mounting system that attaches under a water bottle cage, so you don’t have to fill up your pockets.
Don't know how to change a tire? Check out this Bicycling Magazine how-to article
Patch Kit
Sometimes, we may have extra bad luck and suffer more than one flat tire in a ride. Atrocious, right? That’s why you should also carry a puncture repair kit with you. This could be patches for tubes or bacon strips and a dart for tubeless systems. The main thing is you want to be able to patch your tubes and get back to riding.
Multi-Tool
It’s not for making big repairs, but a multi-tool can save your bacon in countless ways. Saddle in the wrong spot and causing you pain? There’s a tool for that. Pedal feeling loose? There’s a tool for that! Is your fender rattling so much that it’s annoying your riding buddies? There are multiple tools for that. Every year, the cycling multi-tool gets a little bit smaller and generally adds another tiny screwdriver or Allen wrench to the offering. After just one use, it will likely become your best friend.
Chain Quick Link
Breaking a chain is just about the worst thing you can do on a ride, save for crashing or wearing mismatched socks. It doesn’t need to signal the sudden end of a ride though if you have your multi-tool and a spare quick link.
Here's a good Wikihow how-to when it comes to chain repair:
Saddle Bag
Want a handy place to store all of these things? We suggest our True Grit saddle bag. It’s large enough to hold all of the items listed above and then some! It also features an inner pocket for your ID and cards, a key fob, and an elastic strap to hold your tools in place.
Cycling Wallet
We're not one for rules (Velominati Rule #31), but some say a saddle bag destroys the aesthetics of the bike. If you agree, then you'll want our Tour de Fierce Cycling Case instead. It will fit everything you need plus a little bit more. And it fits nicely in your jersey pocket.
We honestly don't care what you use to hold your cycling essentials (wallet, saddle bag, ziploc bag, brown paper bag), we just want you to be prepared.
Having a well-stocked cycling wallet or saddle bag on your next ride will make sure you always have luck on your side. A few extra grams won't kill you, and you don't want to be that person who never has a spare tube. No one likes that guy.