PROBLEM: Nuts, you got a flat. But once the tire is off and the tube is out, you can’t see anything that caused the puncture.
SOLUTION: This is worrisome because if something sharp is hidden in the tire tread, it’ll quickly pop the new tube.
First, gingerly feel around the inner circumference of the tire. Don’t like prickly surprises? Then wipe with a rag. It should snag on something sticking through, but your fingers do a better job.
Find something? Get all of it out. You might need to dig with the screwdriver tip on your multitool.
Can’t find anything? This is why it’s smart to mount tires with the label centered over the valve stem. (It looks pro, too.)
Pump air into the tube and listen for a hiss on its outside circumference. See where the hole is in relation to the valve, then look the same distance from the tire label. This pinpoints the suspect area. If a close inspection still doesn’t find anything, you can safely assume that whatever popped the tube didn’t stay in the tire.
If the hole is on the tube’s inner circumference, it came from something the rim strip isn’t covering. Find the flaw and correct it before installing the new tube.
If you find two little parallel slits, your flat was caused by riding into something hard enough to cut the tube between the rim and tire. This is called a pinch flat or snakebite flat. It’s rare if you keep your tires inflated to their recommended pressure.
Stan Purdum says
I carry a pair of tweezers in my tool kit to remove tiny wires or an embedded glass fragment sometimes found in the tire after a flat. They come in handy when the offending item is too small to grip with fingers and not removable with a screwdriver..
Dave Waycie says
If I don’t find the offending “sharp” at first, I turn the tire inside-out, which usually makes the wire or fragment more visible.
George Straznitskas says
I do the same Dave, then if the sun is out I use the sunlight to help highlight the little bugger.😉
Where I live, most flats are caused by thorns (usually small and from tumbleweeds). Since the thorns are small and usually embedded in the tire, a screwdriver, pliers or tweezers is not effective in grabbing/removing the thorn. I carry a short piece of a spoke with a sharp end (I use a grinder to sharpen a point on one end). This pick is usually effective in picking out the thorn. I also inspect my tire after every ride and pick out any thorn (or other potential bad actor/object) before it has had time to work its way through the tire and into the tube.
Roy Bloomfield says
” . . . tweezers is not effective in grabbing/removing the thorn” … Actually, good tweezers are VERY pointed at the tips, and VERY effective, unlike the cheap grocery store variety. If the object can’t be removed by a good, small tweezer, than it likely isn’t in the tire anymore. I also carry collapsible reading glasses in my seat bags, for the occasional hard to see object in the tire.
Kerry Irons says
To echo what Dave Waycie says, turning the tire inside out and flexing it can not only help find the sharp object but make it easier to remove. To the more general topic, I’m always amazed by people who have a flat and “don’t have time” to look for the source of the flat or simply don’t look. And then they tell a story about having to call for a ride home.
My record for flat repair at a bike shop on a university campus, where flats are common, and where students, even in engineering, don’t know how to repair a flat, is somewhere around 30 in a day shift, which went past closing time (as it usually does). Thorns, common causes, are easy to find if one aligns the tube with the tire to find the locus of the puncture, and then feels the inside surface of the tire. Staples and construction debris also are fairly easy to find. A piece of glass or a piece of metal that has “worn into” the tire tread is hard to find, and difficult to remove. Invert the tire to find it. Feel. Look. Then dig. We use a sharpened spoke or awl to probe and dig. Tweezers work, too. Underinflation a problem? Virtually EVERY bike that comes in has underinflated tires, and we offer a free tire filling station outside the shop, 24/7.
Don Macrae says
We’re assuming that the tyre’s been installed with the label at the valve hole – that’s worth an explicit mention. Next, if you can keep track of which way around the tube was when you removed it you’ll know in which direction from the label to look for the cause. Tubes ought to have a label on one side to help..
Jim Langley says
Most people don’t ride with rags, but most people do ride with gloves on. So, remove a glove and stuff it fully inside the tire. Then slide it around inside the tire completely in one direction. If it doesn’t snag on anything, you’re not done yet. Next slide the glove around completely in the other direction. It might snag because some things that get stuck in the tire – like a little piece of wire – can go in at a certain direction. You won’t feel it at all unless you go against its direction.
I use my hands sometimes, too, but I have cut my thumb on a piece of glass in the tire bad enough that it kept bleeding for awhile. So, I tell folks it’s smarter and safer to use the glove.
To flat-free rides!
Roy Bloomfield says
Aside from tweezers (small ones with sharp pointed ends), I carry a cotton ball in my saddle bag(s) for help finding the object which caused the flat.
I have long carried a bit of a cotton ball tucked under the rubber band holding the spare tube in its rolled state. When inspecting the tire post-puncture, wiping the cotton ball around the inside of the tire usually results in a ‘flag’ of a few strands of cotton. Easy to find the culprit!
Allan Bridge says
In New Zealand sometimes punctures are caused by steel slivers from steel belt car tyres (from idiots doing burn outs or using old tyres) , or hedgehog quills, both almost impossible to find on the road repair. To overcome this I find the relationship of the tube to the tyre and sleeve all punctures, for better sorting out when I get home under bright lights and a steady hand.
Rick Schultz says
What about those flats that no matter how hard you look, you find nothing in the tire. No snakebite, just a single hole. We’ve all been there, those are the most frustrating cause you know you will probably get another flat.
Ken Goldman says
I always air up the tube before repairing it in order to find the leak. Although I mostly remove the tube from the tire, I leave the valve stem mounted in the rim. When I find the puncture, it’s very easy to realign the tube with the tire. No label needed.
I never cease to be amazed at the number of people who want to tell you about how many thousands of miles they’ve gotten out of tires and/or tubes. If you want fewer flats don’t ride your tires and/or tubes to the point of failure.
Kerry Irons says
Unless you are defining failure as casing failure, I have yet to see any actual data that shows that riding a tire through its useful life results in more flats near the end of the line. Continental puts wear indicators on some of their tires, and when the tire is considered worn out (by Continental) the casing is just visible through the center of the tire tread.
Jerry Kinnane says
And don’t forget to rotate your tires front to rear my rule of thumb is every 6 months
Nicholas Gimbrone says
I find easier and more efficient to always rotate tires front to rear… the rear wears out faster, and it is much more critical to have “good rubber” on the front (you do not want a front blow-out, and even flats are much easier to handle on the rear then the front). So, when a tire needs replacement, move the more worn tire to the rear and put a new tire on the front. Always replace the tube when you put a new tire on too. Replace tubes once they have reached your limit for how many times you are willing to patch them (tolerance varies by rider and their fiscal situation).
Once one has found the offending item and removed it from the tire, there remains a potential problem. If the tire is left with a small puncture, it may still be large enough that the new inflated tube will ulcerate through the tire. Then after a short while of riding, the road will abrade the tube, and it will flat. Always carry something in your tool kit that will serve as a “boot.” Even a folded dollar bill about 3cm x 5cm will do. Before fully inserting the new tube, put the boot between the new tube and the tire at the location of the puncture. Then complete insertion of the new tube and inflate.
When you get home, remove the wheel, tire, and tube. It may be possible to repair the tire. My solution is to use duct tape. Cut one piece about 1cm x 1 cm and place it over the puncture point. Then cut another piece a little bigger about 1.5 cm x 1.5cm and put it over the first patch. This should work. Insert the tube and inflate it well more than usual, perhaps 115 -120 psi. Then leave it over night. Check in the morning to see whether the duct tape is pushing through. It is very unlikely. If it is not pushing through, you should b good to go.
I have a friend who keeps a bit of duct tape stuck to a water bottle that he uses. And, yes, he is a Boy Scout leader…
Another option that I use is to store a few small pieces of TyVek (house wrap but also used for many packages) in my seat bag. Tyvek is very tough (but light) and can “smooth” out rough edges enough so you can make it to your destination and repair the tire with a better “boot”.
Christian Burkhardt says
I always carry a spare tire. Two spares when I’m on a brevet. Folding tires a pretty light. That way I just put on the new tire and tube without wasting time looking for the puncture. At home I can find the problem at my leisure.
Even easier, I’m currently riding Tufo tubular clinchers with 2 oz of sealant. So far my spare tire has stayed in it’s seat bag. Knock on my wooden skull!
Christian Burkhardt says
I’ve found that tan side walls make it much easier to visually find the offending shard of car tire belt. Also latex tubes are much more forgiving for me. I pulled a goat’s head out of a tire and expected to loose air. No loss. Was using a Rene Herse “Extra Light” tire.
Bruno John says
While cycling, I noticed that my wheels wobbled. I checked and the tire was flat. I tried to fix it for the next ride, but the same thing happened. This time, I started to wonder “why does my bike tire keep going flat?”
David Keller says
I went through this years ago and found the rubber liner that covers the spoke ends had slipped and the tube would gradually work into the exposed space, eventually puncturing. A new center strip, carefully installed, solved the problem.
Ken Gibbs says
I have a ebike wheel 26×4 the tires look meaty but that sure is not the case what is the best way to go about avoiding a flat. Does adding a strip of material between tire an tube plus some type of liquid in the tube both at the same time does anyone fix wheels like that ? Thanks
Back in 2004 I bought a Gary Fischer Dual Sport and flatted on nearly every ride where the roads or trails were wet or damp. I tried insert strips and Slime tubes until I had a wheel filled with green goop. The tires had a chevron tread pattern that would hold debris and their sharp edges would be pushed thru the tire causing a puncture . Turns out the tires spec’d were for slick rock dry conditions. Tire change fixed the problem. The bike is now used by my nephew. The tires were 700c x 42 IRC Mythos XC Slick. Finding inserts for your four inch wide tires may be problematic but the added weight with inserts and filled tube should not be noticed with an ebike. I’ve gone to tubeless on every bike that I can, that’s an option if your wheel and tire are tubeless ready.
Wrap your spare tube in an old sock. Fold it back on itself and you can tuck your tire levers, etc. in it as well. You now have a rag to cover your hand to keep the grease away AND a great way to find that object that caused the flat without cutting your finger.
I live in Arizona and ride 6-7 thousand miles a year including self- supported bicycle touring for months in Europe. My touring and road bikes all have Mr. Tuffy tire liners. I also am anal about keeping tires inflated, and wiping the tires after every ride. Arizona city roads have a lot of debris including gravel, tools, glass, strips of metal from auto tires, goat heads, etc. When I first moved to Arizona I had 6 flats the first week. Since I don’t patch tubes I knew I had to find a solution. In my mind, riding with a patched tube is knowing that the tire will flat in the near future. Basically, a ticking time bomb. That is when I started using tire liners. If I have more than 2 flats a year that is a lot. They are very simple to install. Give them a try.
A piece of lycra or pantyhose works well for wiping the inner surface of a tire to find what is causing flats.