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I have had four flat tyres in less than two months.

Some more information:

  • I've only experienced repeated flats since I started using racing bikes (two months ago).
  • I'm 194cm tall and weigh 74kg.
  • I have cycled several 80-140km rides in the past two months.
  • I only cycle on-road.
  • I avoid potholes / manholes / cracks etc as much as possible (but not completely).
  • It first happened on a cheap, unbranded second-hand racer.
  • I bought a much newer (mono-q) racer and experienced a flat tire after within the first 100km.
  • Even after getting a new bike with brand new tires, and having it all fitted professionally to my specifications, I'm still experiencing flats.

It's really perplexing. What might I be doing wrong?

Edit: mystery solved (for now). I think it's just a matter of me using the wrong tyres. The ones I was using are designed primarily for going fast, meaning they are apparently too thin / smooth to cope with small stones etc. Hopefully getting thicker and more textured tyres will solve this.

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    Hello and welcome to the bicycles! Four flat tires in two months is definitely much (and irritating) but not unbelievably often. Even without installation errors and exploitation mistakes, puncturing is still a probabilistic process. One can reduce the probability but never have it to zero. Besides, there are many more factors that may potentially contribute to explaining of the problem that you have not described, like the type of puncture. Maybe the roads you ride are that bad and have too much litter. You can still try using puncture-resistant tires or converting to tubeless. – Grigory Rechistov Mar 10 at 7:23
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    What tire brand are you using? Spending a little bit more on a tire with increased puncture resistance is worth the extra bit of decreased rolling resistance – Dan K Mar 10 at 9:48
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    Where's the hole(s) in the tube(s)? Are they always in the same place? When you get a flat and remove the tube, note the exact orientation of the tube as you remove it, go find the hole in the tube (if necessary, put some air in it and hold it under water in a sink or bucket), then go look closely at the tire and wheel where the hole was. – Andrew Henle Mar 10 at 9:54
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    What tyre pressure are you running on which tyres? – Vladimir F Mar 10 at 15:17
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    Most likely your tire pressure is too low. – Daniel R Hicks Mar 10 at 17:05
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I see three possibilities:

  • Your tire pressure is too low and you are getting pinch flats. As a reference point, with 25mm wide tires and your 74kg weight I’d use at least 6bars (600 kPa) of pressure, better 6.5 or 7. Refill every week or so. Usually with pinch flats you’ll have two holes in opposing sides of the tube, like a snake bite (hence why they are also called snake bites).
  • Spoke ends or burrs are poking into the tube. Check that the rim tape is seated properly and nothing is sticking out of the rim. Also check that nothing is sticking out of the tire. Sometimes the piece of glass which caused the previous flat is still sticking in the tire.
  • Bad luck or lots of sharp debris on the road. You could use more puncture proof tires, use tire sealant or go all the way and go tubeless.
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  • Pinch flats sounds like a likely contender. I was wondering, I tend to cycle in the highest gear I can manage. Perhaps this puts too much pressure on the bike, making me more venerable when I cycle over stones or bumps in the road. Do gears or riding position have any influence on pinch flats? – Hello World Mar 10 at 10:45
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    @HelloWorld: I don’t think gear selection makes much of a difference for pinch flats but riding position certainly does. The problem is that sometimes you just hit a pothole or other sharp edge without having time to react (slow down, go around) or change your riding position (get out of the saddle, shift your center of gravity, etc). So I think there is no way around sufficient tire pressure. – Michael Mar 10 at 11:24
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    @HelloWorld if you had a pinch flat, you would see the distinctive snake bite holes. This is why it’s important to inspect your tube and tire after a flat, even though it may seem fussy. – Weiwen Ng Mar 10 at 14:25
  • It’s also a good idea to remember where the hole is and check that area of the rim and tire thoroughly. Use the valve and tire labels to determine the position. – Michael Mar 10 at 15:32
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    @RyanStone: It really depends on the pressure. If your pressure is low enough even speed bumps can cause you to “bottom out” and pinch the tube. – Michael Mar 11 at 8:11
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there are a few things to check:

  • make sure the rim tape is in good condition (no tears/holes, make sure it's properly aligned in the rim)

  • remove rim tape and check if any spokes protrude more than approx 1-2mm past the top of the spoke nipples, if they do consider shortening these spokes with a file, Dremel or the like or adjusting the spokes such that they are no longer protruding (if possible whilst keeping the wheel true/round)

  • check rim bed/edges (where the tire contacts the rim) for damage (sharp/pointy spots which could potentially damage the tire), if you find any sand/file them down so they're smooth

  • check your tire for pieces of metal/glass/other objects embedded in/under the surface (by rotating the tire whilst removed from the wheel and pinching it every 2cm approx to reveal any splinters, do this on both the inside and outside of the tire

  • check if valve hole has any sharp edges

  • whilst installing inner tube make sure it is not pinched in between rim and outer tube (inflate inner tube just a bit, check if it is not pinched anywhere and if all is good inflate the rest of the way)

For fixing flats I personally find it useful to clamp the inner tube with patch in between a bench vice (potentially with some pieces of wood in between the vice and the tube/patch for wider inner tubes), you could also use screw clamps for this purpose.

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    Also, you can check your tire with a cotton ball - slide it along the inside surface of the tire. Anything stuck in the tire will grab a few threads from the cotton ball. Using your finger for this can also work - the debris will be where you finger got stabbed or cut. ;-) – Andrew Henle Mar 10 at 9:52
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    Depending on how experienced the OP is, they may not have successfully removed debris stuck in the tire, which then caused a repeated flat. This would be my first suspicion, which the other answers don’t address. – Weiwen Ng Mar 10 at 14:23
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Others have already suggested some likely explanations, which I agree with. If you're not already doing this, I suggest that you line up the labels on your tires with your valve stems. Aside from looking more "pro," this has a real benefit: when you find the punctured spot in the tube, you can map that back to the tire. This is important, because a tiny shard of glass can get lodged in your tire and cause repeated flats. Finding these even when you know where to look is hard enough.

When you get a flat, remove the tube and find the puncture by airing it up a little. You can usually get pretty close by listening for the leak, and I find it helpful to hold the tube close to my lips, which are more sensitive, to find the exact spot. (This is also helpful for diagnosing flats caused by protruding spokes on the inside. If you have the luxury of doing this at home, you can also roll the tube through a bowl of water to look for bubbles.) Mark that spot and hold the tube up to the wheel, aligning the valve stem with the valve hole. There are two spots on the tire that could be the puncture site (clockwise or counter-clockwise from the valve stem). Check both carefully. Look for a tread cut, and pinch the tire to expose the inside. Feel the backside of the tire for anything poking through. Sometimes you'll need needlenose pliers to extract the offending pointy bit.

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    A spray bottle with soapy water often does the trick, too, and without having to take the tire and tube off the bike. – computercarguy Mar 11 at 19:22
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This could possibly be a case of cheap low quality tyres. It is common for bikes to come new with poor quality tyres that do not have any sort of puncture protection layer.

Manufacturers do this to keep the price point of the bike down reasoning that anyone that cares about tyres is likely to have their own preferences anyway.

So my advice would be to check the brand and model of your tyres and look for some reviews. If they are not a good quality tyre then replacing them with something better could solve your problems.

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Along with all of the other excellent suggestions I'd like to add -
be road aware.

As you ride keep an eye on the level of road debris (along with an eye on traffic, pedestrians and everything else!) far enough in front of you that you can make an adjustment if you need to. Plan the best path for your tires.

When you see tire hazards on the road - metal, gravel, thorns the glint of glass, the metal grate designed to trap bicycle wheels - select a better path and ride there. Road awareness is important on and off road.
The path you ride will tend to have tire hazards in certain places. Be aware of where that is and adjust your path. In the U.S. the shoulder of the road is where all the stuff that will puncture my tire ends up. When possible I stay off the shoulder.

Sometimes you have to take it on the chin and ride through garbage but often you can reduce your chances of getting a flat by selecting the clearest path and riding there.

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  • Speaking of broken glass and glinting: polarized sunglasses reduce glare (i.e. light reflected off objects like glass or surfaces like ice). I discussed in a recent answer why polarized lenses may not help riders: bicycles.stackexchange.com/questions/5673/… – Weiwen Ng Mar 10 at 18:02

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