What to Do About Fixing a Flat Bike Tire While out on a Ride
It’s a nightmare scenario for any cyclist: You’re halfway into a 50-mile ride when you suddenly begin to feel your wheel rumbling against the pavement. You pull off to the side to examine your tire, and your fears are confirmed. It’s a flat.
Now, if you had come prepared with the right supplies and experience fixing a flat bike tire, this would only be a minor nuisance. But as it is, you have neither, and now you’re stuck 25 miles from your car with no easy way to get back.
Most likely, you’d like to avoid this situation. And, since your chances of evading a flat tire are slim to none, it’s best to prepare yourself for the inevitable. Here again, our friend and cycling mentor Coach Darryl comes to save the day.
What Causes Flat Tires?
First things first—let’s get our terms straight.
“Everybody calls it a flat tire and it isn’t,” says Coach Darryl. “It’s actually a flat tube.” Unless you’re riding the rare tubeless road bike wheels or a fat-tired mountain bike, you’re going to be changing the tube on the inside of the tire, not the tire itself.
So why do these tubes go flat with that protective layer of thick rubber tire around them? When road cycling, Darryl notes, the culprit is usually a construction staple or wire, though sometimes it can be glass, a rock or just a big bump.
You’re most likely to have to fix a flat bike tire — or rather inner a flat tube — when it’s getting old, after the first 1,000 or 2,000 miles. As your narrow road tires wear down, the contact surface (where the tire touches the road) expands from a narrow point to a surface roughly 30% wider than it was. This wider contact area makes it that much easier to pick up a sharp object from the road. The tire also grows thinner, providing less of a protective barrier for the tube.
Occasionally, though, you can get a bad tire or tube (or you put the new one in wrong — we’ll get to that). If that’s the case, you’ll know it quickly, probably on the first ride. For this reason, Darryl recommends giving yourself a 10-day lead time to try out new tires before a big ride.
Bicycle flats are a fact of cycling life. In fact, you may get more than one on a long ride. Darryl once had six in one 25-mile ride. So, yeah, Coach always comes prepared.
He recommends bringing two spare tubes on a 30-to-45-mile ride, a third if you’re going more than 50 miles, and a fourth if you’re going over 100. You can stow these last two in your jersey pockets.
Beyond the tubes, you should also bring several CO2 cartridges that you can use to refill your tire in a matter of seconds. Without these, you’re cranking a hand pump 200-plus times for several minutes. Yes, that’s as exhausting as it sounds. If you’re already invested in a long ride, you do not want to expend extra energy fixing a flat bike tire.
Do bring a hand pump as a backup, along with two valve adapters for your CO2 tanks and two tire levers (small plastic "tire irons” for prying the tire off the rim).
8 Steps to Changing Your Flat Tire
With the right equipment and a little know-how, you can change a flat bike tire and be back on your bike in 10 minutes. Here’s the step-by-step guide.
1. Take the Wheel Off
This should be the easy part, as most wheels these days are quick-release or through-axle (depending on your brake type). If your flat is on the back, though, be sure to change your gear to the smallest cog, furthest from the bike frame. Your derailleur will naturally spring to this position when you remove the chain, so that’s where you want it to be to make it easier to get the chain back on the wheel when you’re finished.
2. Carefully Separate the Tire From the Wheel
Once you have the wheel off the bike, let any remaining air out of the tube so it’s easier to detach from the rim. With the air out, you’ll need your tire levers to remove the tire.
Starting at the opposite side of the valve stem, carefully use the pointed end of a tire lever to pry the tire and tube loose from the rim. If you encounter any resistance, use a second tire lever about three inches from the first, then pry at both points.
As it begins to separate, slowly move the tire lever around the tire, gently prying as you go, until you have the tire completely removed from the wheel.
3. Pull the Tube Partially Out
Before you completely remove the flat tube, you need to find the hole. Otherwise, the object might still be in your tire, ready to puncture your new tube when you get back on the bike.
Starting furthest from the valve stem, pull the tube out of the tire all the way, leaving just 2 or 3 inches on either side of the valve. Once you find the hole, you can then line it up with the tire to see if the cause of your flat is still lodged there. Finding the cause is essential to ensure you fix your flat bike tire once from the initial cause.
4. Find the Hole and Remove the Culprit
With the flat tube hanging partially out, use a hand pump to blow it up just enough to hear where the air is leaking. If you have trouble hearing it, put your hand or your face close to the tube to feel the air seeping out. Darryl notes that, if you’re fairly certain that a bump was a cause, rather than something sharp, you can skip this step.
When you find the hole, line it up with the tire to find the culprit and remove it. In most cases, Coach Darryl says the tire will be ready to hold a new tube. In the rare instance that you have a damaged side wall, though, you can use an old piece of tire or even a folded dollar bill to cover the hole and prevent the new tube from forcing its way through and going flat. This isn’t a replacement for a new tire, mind you, but just enough to get you home or to a bike shop.
5. Remove and Replace the Tube
After you’re sure there’s nothing left in your tire to ruin your new tube, you can completely remove the old one. Before you begin to put the new tube in, blow it up just enough to give it its normal shape. This will keep it from getting twisted or folded when you seat it inside the tire.
Once it’s partially blown up, start by seating the valve stem where it fits, then work your way around from both sides of the valve to get the tube all the way inside the tire.
6. Put the Tire Back on Your Wheel
This is the hardest part of repairing a flat bicycle tire. You’ll start at the valve again here, pushing it up from the inside of the tire so that it pushes the tire higher than it would normally be on the road. This will give you enough clearance to get the tire around the rim first at the valve stem.
Now work your way around from both sides of the stem so that you’ll finish at the farthest point from it. Those last 8 inches or so are going to be the most difficult, and Darryl recommends keeping your gloves on and using your palms (not your thumbs) to push the tire onto the wheel. The hands are far stronger than the thumbs, and the gloves will protect your palms.
Although some people use their tire levers to get those last few inches around, Coach Darryl cautions against this because you can inadvertently pinch your tube in the process.
7. Make Sure the Tire is Seated Properly
It’s important not to rush past this part and start blowing up your tire. Slowly examine all the way around the wheel on both sides, looking for any sign that the tire isn’t seated right. There should be a ridge about 1/8 of an inch away above the rim all the way around. If this is too far out at any point or you see any tube sticking out around the edges, you need to adjust the tire.
8. Inflate and Check Again
Again, this is where those small CO2 cartridges will come in handy to save you time and effort. But be careful — these cartridges fill your tire so quickly that it’s easy to overfill and pop your tube. (Keep in mind, also, that you’ll probably need to refill the tire again when you get home, since the smaller CO2 molecules will leak out more quickly.)
Attach the cartridge to the adaptor valve (the piece that connects it to the valve on the wheel), screwing it all the way in. Position the valve on your wheel toward the ground so you can apply pressure to the valve and not leak any CO2. Then tighten the other end of the valve adapter all the way onto the valve on the tire.
Unscrew the tank just enough to release the CO2 into your tire, while holding your hand on the tire to check the pressure as it fills. (The tanks frequently have more CO2 than will fit in your tire, so you can pop your new tube if you’re not careful.) As soon as your tire is full enough, tighten the tank back down to stop the air flow.
Give everything one more check to make sure the tire is seated correctly with no tube sticking out. If everything looks good, put your wheel back on your bike and you’re ready to ride.
And, finally, try the process of fixing a flat bike tire from the comfort of your home before you attempt it on the road. It’s best to get used to the process before you find yourself threatened with sunset or bad weather.
You can find more insights from Coach Darryl over at his website.