Some cyclists get flats all the time. Others ride for months without a problem. Whichever group you belong to, one thing’s for sure: flat tires are an inevitable part of cycling, and, sooner or later, you too will have one.
When your tire goes flat, how do you know if it’s because of a puncture or something else? After all, a flat tire is one that’s deflated, and that can happen for more than one reason.
Flat Tire vs. Punctured Tire
A flat tire is a tire that’s run out of air for one of many likely reasons. A punctured tire, on the other hand, is a tire that’s run out of air because it has one or more holes through which the air escapes.
Some cyclists don’t check tire pressure before they get on their bikes and start riding. Tires lose 1-30 PSI every day and, if it’s been a while since you filled up your tire, it’s easy to think you have a puncture when in fact all you need is a pump.
When one of your tires has gone flat, you could also have a leaky valve. Valves are critical components on bike tires because they keep the air in under pressure. That said, they do deteriorate over time and can start leaking.
If you ride with tubeless tires, it’s important to determine the source of the leak before you get a new tire. Good tubeless tires don’t come cheap, and a leaky valve can trick you into thinking you have a puncture when you really don’t.
Clinchers and tubular tires can also have leaky valves if the core on the stem has gone loose. Inflate the tire well, then spit liberally on your finger and cover the valve with saliva. If a bubble forms, you know you have a problem.
How to Identify a Punctured Tire
So how can you tell if you have a puncture?
When in doubt, follow the fool-proof five-step checklist below. By the time you’re done, you will either have found the puncture or be able to rule it out.
#1: Does your tire lose pressure too fast, too often?
It is normal for clinchers and tubular tires to need to be topped up once or twice a week, especially if they’re a few years old and they’ve seen things, and for tubeless tires to need to be filled up once or twice every two weeks.
But if your tire goes flat on you a day or two after you’ve filled it, you have a problem. Continue to the rest of the questions in this list to determine if that problem is in the tire or in the valve.
#2: Do you see any foreign objects on the outside of the tire?
Hold the bike with one hand to lift the wheel that’s going flat, then turn the wheel slowly with the other hand to observe the outside of the tire.
Can you see any pins, nails, metal wire, pieces of glass? Sometimes, though not always, the cause of the problem is right in front of your eyes.
#3: Examine the tire’s carcass for cuts and rips. Do you see any?
Remove the tire and the inner tube (if you have one) from the rim. You’ll need to squeeze a couple of tire levers under the bead and put in some elbow grease at this step, so get your tools ready. Don’t use screwdrivers and other tools that can make things worse.
Examine the fabric of the tire carcass for foreign objects. Use your eyes and not your hands; it’s too easy to cut yourself, and you do not know what you’ll cut yourself with.
If you find any foreign objects, remove them with a compact and precise tool such as a pair of tweezers.
#4: Examine the tube for punctures. Can you find any?
Having separated the tire from the tube, inspect the tube inch by inch for any visible punctures.
Larger holes are easier to find, but they’re also more difficult to repair. There are cases where the hole is so large that it’s simply beyond repair, whether with a patch kit or Slime sealant.
If you can’t see any visible punctures on the tube, try the next step.
#5: Inflate the inner tube and listen for hissing. Can you hear it?
If your tire has a tube, now is the time to determine how badly that tube is punctured and whether or not it can be repaired.
Inflate the tube as much as possible without blowing it out; higher pressure makes it easier to detect punctures. Hold the tube close to your ear (but not too close) and turn it slowly. You will hear a hissing sound as the pressurized air escapes through the hole.
(If your hearing is poor, submerge part of the tube in a large bowl filled with water and turn it slowly. You will see air bubbles coming out of the puncture.)
Can I Keep Riding With a Punctured Tire?
The long answer short is that it depends on the cause of the flat, the severity of the puncture, and how many more miles you have left to go.
For example, you can’t fix a burst inner tube. And, to avoid having to walk home with the bike by your side, you will have to replace it on the road or at a nearby bike shop.
Pinch flats, the symmetrical punctures you get on underinflated tires when the inner tube gets pinched between the tire bead and the edge of the rim, are often too large to repair by patching or sealing.
Ideally, you’d carry a mini pump, small wrench, a couple of tire levers, one or two inner tubes, and a few patch kits or a bottle of sealant with you at all times. This can spare you a long and exhausting walk to the nearest gas station, car stop, or bike shop, especially on long rides to rural areas.
You could, of course, try riding your bike with a flat tire and see how far you get. If the puncture isn’t too bad and you have a mini pump at hand, you can minimize the damage to the rim.
The only problem is that if you damage your rim beyond repair, you’ll have to pay a lot of money to repair the bike after you get home. (Still, it beats being stuck up in the mountains or somewhere in the dessert.)
The Bottom Line
If your tire is losing pressure too quickly, it’s a sign that you either have a leaky valve or a punctured tire. Riding with a flat tire can damage your rim and make your bike hard to handle, so you need to find—and fix—the cause of the puncture quickly.