All my life I have bought used speed bikes. I finally sprung for a new bike which I use to commute to work (6 miles each way). It's a Giant Contend3 (XL).

Giant Contend 3

I keep getting "pinch flats".

The bike store experts tell me it's because I'm not pumping enough air into my tires. I have a pump. I am now pumping twice a week. (It is baffling to me that skipping pumping for a week would result in a flat, as I have always just pumped my tires once in the spring and left it at that).

I got another flat yesterday, despite my regular pumping.

I'm ready to write off the new bike and go buy another used bike.

Is there something else I should be considering?

In response to the comments below, I weigh 220 lb (100kg) and I target 100 psi (6.9 bar) on the gauge.

  • 1
    How much do you weigh?
    – Batman
    Commented Feb 17, 2017 at 15:43
  • 3
    What pressure are you pumping the tires to when you are doing the inflation?
    – Ross
    Commented Feb 17, 2017 at 15:46
  • 2
    Edited to add picture, since I'm very visual. And added SI unit conversion for weight and pressure (yeah, yeah, bar aren't technically SI, but they're a whole lot more SI-ish than psi).
    – RoboKaren
    Commented Feb 17, 2017 at 17:49
  • Hoity-toity tubes (or tubeless tires) tend to leak down rapidly -- you may need to pump daily. (When you start to pump, after 3 days, what does the pump's gauge initially read?) Commented Feb 17, 2017 at 17:55
  • When you replace a tube, there's rim tape covering the spoke nipples. Check that the tape is not creased or moved so that it is not covering a spoke hole properly. Note: flats due to this type of issue can look like pinch flats because of how the spoke hole can cut into the inner tube. Commented Feb 17, 2017 at 18:23

8 Answers 8


For road bike tyres you need a pressure gauge -- pumped up so they feel hard to the touch, the tyres could well be at their lower pressure limit. You say it's an XL frame; guessing that you're normally proportioned that could be a fair bit of weight on the back in particular (I'm at the big end for XL bikes, so I don't mean anything negative). That makes it more important to pump the tyres up properly than for a lighter rider (the ideal pressure is higher and therefore air is lost faster). It also makes it more important to look after the bike over potholes etc., by standing up on the pedals if you can't avoid the hit.

That bike ships with 25mm tyres. Running just a touch bigger (28mm) can make a big difference to how long the tyres hold pressure (as can thicker tubes or butyl instead of latex). Depending on the rim width you might win in other ways on a bigger tyre too (absorbing shocks). What width tyres did your old bikes have? If not all of your punctures are pinch flats, tougher tyres would be worth it too.

  • 1
    Would like to add that the thin road-bike tubes leak down faster than MTB or thorn-proof variants do. When I commute on my 23mm wide tire bike, I have to air up on Sunday and Wednesday nights to make it through the week. You are a little heavy for such a narrow tire at only 100psi, if the tire sidewall markings allow--try 120psi or more for your 220lbs. 28mm tires would help a lot if the frame can fit them. Race bikes are picky. Especially for heavier riders. (who knew, right? I'm heavy at 200lbs!)
    – david1024
    Commented Feb 20, 2017 at 22:41

Having so many flats occur is maddening, I feel your frustration. Tire pressure probably isn't your culprit unless you have a rough ride to work. If that's the case, upping your tire dimension to a 28-30mm tire will really benefit you. Otherwise, there's a system malfunction you're hunting for and it's best not to assume anything about the source of your flats and check your whole tire system.

  1. Take a detailed look at your tire, has debris like glass, rocks or metal embedded through the tire? Pick out any debris you may find. Wipe down the inside of the tire with a cloth, not your hand (in case there is debris, you don't want to find it as it cuts your hand).
  2. Check the bead of the tire and make sure there's no nicks, cracks or cuts. You may need to replace a tire if you find cracks or cuts here. This mainly happens with old tires that have dry rot, but it's good to eliminate it as a possibility.
  3. Check your rim. Is it free of barbs, or other debris that would cause problems. Wipe down the rim with a cloth like your tire.
  4. Make sure the rim tape is laying flat on the inside of the rim. If it has moved off center, the spoke holes can cut you inner tube and flat your tire in no time. Additionally, stock rim tape that comes on beginner wheels can be a sharp, hard plastic. Re-center the tape if need be. If the tape as folded, you can pick some up at your local bike shop pretty cheap.
  5. Re-assemble your wheel with minimal tool use. Your tire levers can be your greatest friend getting a tire off, but your worst enemy to getting a tire on. The tool can unknowing pinch or cut your tube only to start your next flat early.
  6. Partially pump up your tire (~30 - 50 psi) and squeeze the tire to seat it properly within the rim. Then pump it up to your 100 psi.
  • Nice list! Since you're getting detailed, I would add a note to make sure you're using an appropriate tube size. With small tires, if you're using a tube one size too large, it's very hard to get the tube to stay inside the tire as you put it back on the rim, meaning it gets pinched between tire bead and rim as you're working the bead back over the rim edge, and you can pinch flat the tube as you're reinstalling the tire. I once went through 3 tubes like this helping a friend fix a flat b/c she had 23mm tires and all I had was 28-32mm spare tubes (which I think is only one size up)
    – SSilk
    Commented Feb 17, 2017 at 21:01

Pinch flats occur when the tire deforms so much that the tube is squeezed hard against the rim. They happen if tire pressure is too low, and/or if you hit something big (like a rock) or jump off curbs. At 220 lbs, you need higher tire pressure than 100 lbs. I weight 110 and ride at least 100. Look for the max tire pressure printed on the side of the tire, and pump the tires to that pressure. (this is not dangerous; the max pressure figure is well below what the tire can actually handle.) And make sure you use a pressure gauge! Getting wider tires is also a good idea. Getting a new bike is not necessary. the problem is not with the bike, only with the tires.

  • Exactly correct!
    – andy256
    Commented Feb 18, 2017 at 6:08

A bike with small tires like that could easily need you to pump once a week (twice a week is a bit much though). If you don't have enough tire pressure, you will pinch flat. Make sure your pressure is enough for your weight -- the tire feeling hard when you push on it is not a good indicator, and you need to use a gauge.

In general, check the inside of your tire for any debris, make sure the rim tape is in place and in good condition, the tube is installed properly (not getting caught anywhere). Sometimes the valves also leak on tubes.

  • 1
    Hmm. Pumping the tires twice per week is normal for me.
    – andy256
    Commented Feb 18, 2017 at 6:10
  • While on 700x28s (with whatever 28-35 tubes the bike shop has) I can get 2 weeks use quite easily, 3 at a push by pumping to the max pressure. So that small difference can be quite significant
    – Chris H
    Commented Feb 18, 2017 at 8:20
  • @andy256 you're a proper road-rider aren't you? Lightweight latex tubes? I doubt that's what the OP has but you never know.
    – Chris H
    Commented Feb 21, 2017 at 16:52
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    @Chris Yes I do ride a road bike, but I use ordinary butyl tubes.
    – andy256
    Commented Feb 21, 2017 at 21:28

Echoing Daniel's question in the comments above, when you're doing your twice-weekly air top-up, and you first connect your pump to the tire, and before you start pumping, what does it read? That will give us an idea of how much air they're losing between each top-up.

Also, I'll second Chris's suggestion of larger tires. Going to a 28-30mm tire will make them way less likely to pinch flat, much more forgiving of not being at "ideal" pressure, and the ride will be way more pleasant (less harsh). The small downside is a slight reduction in efficiency, but unless you're racing somewhat seriously, I wouldn't worry about that, and for a 6 mile commute that really shouldn't hurt you.

If it helps put your mind at ease, my commute is about 15 miles each way and recently I've been mostly doing it on 42mm all-road tires running around 50PSI. They're definitely a bit slower, but we're talking like 2-5 minutes reduction on a 60 minute one-way commute. Going from 25mm to 28mm on a 6mile commute, I'd be surprised if you could measure a 30 second reduction in average commute time.


I had a similar situation to yours a few years ago. I was getting a flat about once every other week. At the time, I had the guys in the shop do my tube changes because I always got pinch flats when I did them myself. After so many replacements, I had a really close look, and I found that a thorn was the problem. A tiny, tiny thorn.

The guys at the shop were telling me I was getting pinch flats, but apparently they hadn't looked very closely, because it was actually a thorn causing all the problems. After I removed the thorn, no more flats. Also, after such lackluster work at the shop, I now do my own tube changes.

If the problem really is pinch flats, and the guys at the shop are doing the replacing, you ought to have them replace it for free. If you're getting a pinch flat so often, it's more likely a faulty installation than too-low pressure, (though if you had a thorn, that may explain why you need to inflate your tires so often...).

  • 2
    Yeah a thorn is not a pinch flat. You should mount the tyre so its always in the same place relative to the valve, and if you always get flats int he same spot then there's something in the tyre or the wheel at that spot. Pinch flats will be distributed about the rim.
    – Criggie
    Commented Feb 17, 2017 at 21:20
  • Yup - I meant to mention that that guys at the shop were claiming I was getting pinch flats, but I found out that it was actually a thorn. Essentially, I wasn't getting pinch flats, but I was told that I was.
    – Nate
    Commented Feb 21, 2017 at 16:22

Maybe there's a "slow flat"? If you have a little pin-prick protruding through the tire, it will put a tiny hole in the inner tube, and the tube will go flat faster than expected (e.g. overnight).

To check:

  • Use sellotape or a marker to remember where the inner tube is relative to the tire
  • Immerse the pressurized inner tube in clean water (perhaps with detergent) to look for a tiny stream of bubbles
  • If you find it then fix the hole in the inner tube AND closely examine the corresponding place on the tire.

Also I'd check my tire every day before riding. If it loses air too quickly, see above.

This answer is similar to Nate's.

  • 3
    The trick is to put the biggest branding on the side of the tyre right at the valve. Its only super-cheap types that have nothing. This way, the hole in the tube leads you to a point on the tyre to check, at most its 50mm long. Worst case is you check two points on the tyre, the same distance away from the valve hole.
    – Criggie
    Commented Feb 18, 2017 at 0:57
  • 2
    ...and if you're running super-cheap tyres there's no reason not to mark them with a spot of paint on the moulded logo. Waterbased ideally, it won't stick very well but will leave a mark. (carrying on from @Criggie's comment)
    – Chris H
    Commented Feb 21, 2017 at 16:48

Snake bite tire punctures have a distinctive look. So assuming that's what you're getting... in my commuter experience there are three factors to a snakebite tire puncture:

  • Hitting a square bump in the road at speed (try not to!),

  • Under-inflated tires,

  • Hardness of the inner tire wall on the back of the tread surface.

The old kevlar-lined (hard inner wall) commuter tires were notorious for practically guaranteeing a flat if you hit a square bump while under-inflated (I once had 14 in one tire). The answer is to make it harder for your rims to bottom out (causing the puncture) by keeping more air in your tires at all times, or if your inner wall was really hard then get different tires that don't have that. You really can't go by how recently you pumped up the tires, since hitting bumps can knock a lot of air out of them. So if you're still getting punctures, check the pressure before and after every ride to learn what's happening on that end.

Also, as noted by other posters, you probably need more rear tire pressure if you're heavier than the average rider, but it probably makes more sense just to get slightly wider tires.

In sum: No need to get rid of the bike since it's just the tires! Check your pressures and get tires that can take the impact better: probably wider, and softer lining. Of course you should take it easy over the road hazards, but if that's not feasible there is a tire for every use case. Good luck :)

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