Selle Anatomica
Row of bicycle wheels with and without tires on them

Patches, Pumps, and CO2: Looking at How To Fix a Flat Bike Tube

Few things in life are certain. Death and taxes, as they say, are pretty sure bets. For the cyclist, you can add a third to that list: flat tires. If you ride enough, flat bike tubes are about as close to a sure thing as you can get.

That probably has you wondering how to fix a flat bike tube. As with anything else that’s likely to happen, it’s best to be prepared for how you’ll deal with a flat. That means having the right equipment — and knowing your best options for how to approach the fix.  

Over the years, cyclists’ methods for repairing flat tires have changed, so you have a few options for how you’ll tackle the problem. Longtime cycling coach Darryl MacKenzie has used them all, so he walked us through each one. Keep in mind that these only deal with bike tubes, not tubeless tires since those are far less common on road bikes.

2 Ways To Deal With the Hole in Your Tube

Before you can re-inflate your bike tube, you’ll need to decide how you’ll fix the hole that caused your flat in the first place. You have two options: Repair the tube or replace it. 

Use a Patch

Your first choice is to fix your tube with a patch kit. You’ll find these sold in various ways, but all kits are small enough to stow easily in your cycling bag. They usually come with a few small patches, some sandpaper, and a tube of adhesive you can use to attach the patch to your tube.

The process for applying a patch is relatively simple if you follow these few steps:

  1. Fully deflate the tube so there’s no tension in the rubber.
  2. Make sure the tube surface (especially around the hole) is completely dry.
  3. Use sandpaper to prepare the surface for the glue.
  4. Apply the glue around the hole, covering a slightly larger area than the size of the patch, and wait a few minutes for the glue to become sticky.
  5. Remove the backing from the patch, put the patch in place, and use a coin to smooth out the air bubbles (like you would when applying a screen protector on your phone).
  6. Wait five minutes for the glue to dry before you inflate the tube.

“This is old school,” says Coach Darryl. “It was extremely popular in the ‘80s and ‘90s, but I haven’t seen anybody do it in quite a few years. It’s a dying skill.” 

Yet that doesn’t mean it’s not a good skill to have. In fact, using a patch kit has several benefits. These kits are cheap and come with enough materials to repair several tubes. They’re small, lightweight and easy to carry. And there’s less waste involved than when you replace every flat bike tube.

There are some downsides to this method, though. Patching is more time-consuming than simply swapping in a new tube, and you can mess it up if you don’t know what you’re doing. Plus, if you don’t need to do it very often, your kit can degrade over time. Above all, note that there’s a limit to how many times you can do it — one tube shouldn’t have more than three patches.

Replace the Tube 

The easier option, at least in some ways, is to simply replace the tube and get back on the road. There’s a bit of a process to this, which we’ve covered in detail in another post. Essentially, you’ll need to blow it up partially and get it seated properly before inflating. 

Overall, this is much faster than repairing the damaged tube. This method is also easier to do correctly, so you don’t end up with another flat five minutes later.

On the other hand, replacement bike tubes take up quite a bit more space in your cycling bag. You’ll typically need to carry two with you, maybe three for longer rides. It also creates a lot more waste than patching tubes and extending their life. Plus, replacing every tube — even for a small hole — can get expensive. 

That said, cost isn’t as much of a barrier as it used to be. As Darryl points out, “This is far more popular now that tube prices are lower than they were in the past.”

2 Ways To Inflate the Tube

Whichever method you use to deal with the hole in your tube, once you’ve corrected the issue, you’ll need to inflate the tube. Here, again, you have two options: Pump it by hand or use CO2.

Pump It by Hand

In terms of getting around, hand pumps for bike tires have come a long way. Decades ago, pumps were so long you’d have to have one attached to your bike’s top tube or seat stay to bring it with you. Thankfully, those days are gone.

“Pumps these days are much smaller,” says Coach Darryl. “They’re about the length of your hand, and they can fit in your bag.”

It’s true. Today’s bike hand pumps are quite portable and extremely reliable. These valuable tools usually accommodate any type of valve, and they’re easy to use.  

It’s a chore to refill a tube this way, though, as it will take you about 200 strokes to do it. You won’t be able to fill it all the way, either. These pumps max out at about 85 psi, so you could risk pinching your tube between the tire and rim — and getting another flat. Finally, the process requires some coordination, and some people find it awkward. 

Use a CO2 Cartridge

If you don’t enjoy the process of pumping up your tube by hand, you can use the speedy option: CO2 bike tube inflators. A CO2 cartridge can fill your tube in a matter of seconds — and it won’t leave you with a tired arm. 

All you need for this flat bike tube fix is a CO2 cartridge and an adaptor for connecting it to your bike. Darryl recommends keeping a few extras of each on hand and wrapping the cartridges together with a rubber band to prevent them from jingling around in your bag. 

When you’re ready to refill, attach the adaptor to the tube’s valve, then screw the CO2 cartridge into the other end, tightening it all the way. Unscrew the inflator slightly to slowly release the CO2, and keep your hand on the tire to feel the pressure. Once the bike tube is full enough, quickly tighten the CO2 cartridge back down to stop the airflow so you don’t overfill. Detach it from the tube’s valve and stow it in your cycling bag, not in your pockets, as that can be a safety hazard. 

The benefits of this method are probably clear. The equipment is small and easy to carry. It’s also an incredibly fast way to fill your tube.

However, there are some definite cons to using CO2 cartridges. First off, it’s easy to overfill your tube and explode it, so you need to practice this at home first. At around $8 per cartridge, it’s pricey. This option is not exactly environmentally friendly, either, as each cartridge only gets you one fill. Plus, you’ll need to refill the tube with air within a few days, as the CO2 will leak out much faster than regular air.

Which Tube-Fixing Options Are Best for You?

Now that you know the pros and cons of your tube repair and refill choices, how do you decide which method to use to fix a flat bike tire tube? There are a lot of factors to weigh, and it will often come down to personal preference and convenience in different situations.

In some cases, though, following Coach Darryl’s rule of thumb may help. When you ride solo, go with your personal preferences. When riding with a group, it’s generally a good idea to consider the group first — and that means choosing the faster methods (replacing the tube and filling it with CO2). Otherwise, you may find yourself riding solo the rest of the way. 

If you do get a flat on a group ride, there’s a way to get the whole group involved and get it fixed fast. Read our post, “What To Do if You Get a Flat on a Group Ride,” to learn how it works.


Look for more insights from Coach Darryl over at his website.

Image by Ty Lu from Pixabay