You just had a flat tire and replaced the tube and in less than an hour you notice that the tube is leaking again. What is going on?!? Having a flat tire when riding to work is annoying in itself, but to have two flats in an hour is infuriating.
Why does your bike tire keep going flat? The most common reasons for repeated flats are:
- sharp object stuck in the tire
- debris in the tire
- sharp object on the inner part of the rim
- spoke piercing or rubbing the tire on the rim side
- tube got damaged when replaced
- tire pressure too high
- tire pressure too low
As you can see there are indeed multiple reasons for your tire to keep going flat. Let’s see what you can do about these to prevent flats in the future and save you further headaches.
Find Where Your Tire’s Losing Air
If you can figure out why you got the flat tire in the first place, then you have a much better chance of preventing recurring flats in the future.
Before removing the tire and the inner tube, note that it’s quite normal for tires to lose some air over time. Even without a puncture, you should check your tire pressure once every two weeks or so. Some air can escape at the valve stem even while your bike is parked in your garage.
If you haven’t used your bike in about a month, and you find that it has lost pressure, pump it up and check it in an hour or so to make sure that you’re indeed dealing with a puncture.
Once you’ve made sure that there’s a puncture, remove your wheel and the tire from the rim. Remove the inner tube and identify the cause of your flat tire by finding where your inner tube is leaking air. You should do this even if you choose to not patch the inner tube, but to use a brand new one since failing to fix the underlying cause leads to repeated flats.
Pay close attention to the following details:
- Where is the puncture located? Is it on the inner part where the tube is in contact with the rim or on the outer part, where the tube is in contact with the tire? Is it on the side of the tube where the tire meets the rim?
- Is there one puncture or are there more than one?
While some punctures are easily visible to the naked eye, others are slow punctures and are impossible to spot.
If you can’t find the hole on the tube by simply looking at it, inflate it, place it in a bucket of water and slowly rotate it. Pay attention to bubbles rising to the top. At times this can be at tricky places, such as the base of the valve stem or along the seams.
Multiple flats in a short time
Sharp object stuck (or debris) in the tire
Often a sharp object, such as a piece of metal or a piece of glass or a broken thorn is stuck in the carcass of the tire that naked eye can’t see. If you fail to remove it, it will puncture the new/patched tube.
Sometimes some debris is inside the tire and that punctures the inner tube.
How to fix it?
Inspect the tire carefully. Run a visual check and run your finger over the inner surface of the tire. If you know the position of the tube in relation to the tire then you will know which part of the tire to check. Your fingertip is very sensitive and will feel even tiny objects. What bare eyes can’t see your fingertip will feel. You won’t necessarily have to replace the tire, most of the time it is enough to remove the object.
Before replacing the inner tube make sure you cleaned the inner part of the tire with a rag so no debris remains inside.
When you buy new tires for your bike, use puncture resistant tires, such as the Scwalbe Marathon (check price on Amazon) or the Continental Ride Tour (check price on Amazon). You can get a more exhaustive list by reading this article I wrote some time ago about puncture resistant tires.
Tube damaged while replacing
When you replace the tube it can get squished between the tire and the rim. The tire can get twisted or bent during the process of installation. This can quite easily occur if the tire is hard to put on the rim or if you use sharp tools, such as a screwdriver, to install the tire.
How to fix it?
Use tire levers for replacing the tire. They are really small and inexpensive. Grab yours on Amazon here.
Before installing the inner tube inflate it slightly and tuck it inside the cavity of the tire: it will prevent the tube from twisting and bending under the tire.
Once the tire is on the rim, move it left and right if it’s not too tight before fully inflating it. This will prevent the inner tube from getting stuck between the tire and the rim.
Spoke pierced through the rim
Sometimes the spoke itself might pierce through the rim and cause the tube to puncture. The rim tape covers the area where the spoke meets the rim. If you see damage to the rim tape, this needs to be fixed before installing a new tube.
How to fix it?
The rim tape should cover the rim drillings and the spoke ends. Make sure that the tape is indeed intact and covers the middle of the rim without leaving any room for damage.
You may have to replace a damaged spoke or put new rim tape on the rim. Rim tapes are inexpensive and are handy to keep at home (they can be found on Amazon).
Running tires at a too low or too high pressure
Having your tires at a too low pressure may lead to pinch flats or snake bites. Pinch flat tires occur when your tire runs at too low pressure and your wheel hits an object on the ground and the rim slices the inner tube through the tire causing two holes on the inner tube.
Too high pressure can cause flat tires too. If you regularly over inflate your tires they are much more exposed to punctures caused by sharp objects as they can’t deflect as much as they are supposed to.
How to fix it?
Inflate your inner tube at the manufacturer recommended tire pressure, which is indicated on the sidewall of the tire. It’s impossible to judge the exact pressure in your tire without a proper pump with a gauge. I recommend having a reliable floor pump and a minipump with a gauge (or at least the floor pump should have a gauge) that can handle both Presta and Schrader valves.
This is true especially for presta valve inner tubes. Presta valve inner tubes have a lock nut on the top of the valve. The lock nut should be tightened after inflating the tire. If you fail to tighten it or over tighten it, you might damage the valve stem that can lead to air leaking.
How to fix it?
Always make sure that the nut is on your valve stem after installing a new tube, and avoid over tightening it.
Too thin inner tube for a wide tire
Typically a too thin inner tube for a wider tire can cause trouble: you need to over inflate the inner tube in order to have it at recommended pressure. Ultimately the tire pressure is too high and the risk of puncture is greater.
How to fix it?
Make sure that you purchase the correct size inner tube for your tire. Here are some links on Amazon to the most common sizes:
For tire sizes up to 25 mm (mostly for road bikes)
For tire sizes 25-32 mm (some hybrids, most gravel bikes and cyclocross bikes)
For tire sizes 32 – 47 mm (some hybrids, and MTBs)
Rim damage on tubeless tires
If you have a tubeless tire then you need to pay attention to the rim when replacing the tire. If the rim is deformed then the seal is compromised between the rim and the tire and so the air can leak.
How to fix it?
Make sure you fix/replace the proper component: tire or wheel.
Find the Type of Puncture to the Cause
Here are the most common types of punctures and their possible causes.
|One or two holes on the sides, less than an inch apart from each other. They appear as tiny cuts.||Pinch flat or Snake bite. You bottomed out your rim and your tube got pinched between the object and the rim||Inflate the tire to a higher pressure so your rim doesn’t bottom out|
|One hole on the outside of the tube||You ran over a thorn or another sharp object, which pierced through the tube||Inflate tire to correct pressure and use puncture resistant tires|
|A hole or a tear on the side of the tube||The tube got damaged when it was installed||Make sure that the tube doesn’t get caught between the tire and the rim during installation, and don’t use sharp objects to install your tire.|
|Hole on the inner part of the tube||Damage caused by spoke or debris on the rim||Check and fix spokes on your wheel, make sure that the rim tape is inserted correctly and has no debris|
|Burst tube||Too much pressure||Don’t over inflate the tire. The recommended pressure is on the sidewall of the tire|
|Hole at the base of the valve stem or damaged valve stem base||Damage caused by rim drilling||Make sure you tighten the nut on the valve stem (Presta only)Make sure that you use the correct size inner tubeRun tire at the recommended pressure|
Tips and tricks to increase puncture protection
The kind of tire you use greatly influences your puncture protection. Low quality tires or some racing tires come without a thickened wall, thus increasing the chances of a flat.
I have experience with the Schwalbe Marathon Plus and Continental Ride Tour tires, and they both prove to be excellent in terms of puncture resistance. I personally use both of them and I have never had to deal with a flat due to them failing me.
You can further increase puncture protection by using a tire liner, such as the Mr Tuffy (check price and availability on Amazon). This is a separate layer that is placed between the tire and the inner tube, reducing the chances of an object penetrating both the tire and the tube.
If you ever had two flats in less than 24 hours you certainly know how frustrating it can be. If you would like to focus on enjoying the rides instead, it is definitely worth checking the above listed options.
Enjoy the ride!