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I have been getting flats every 20-30 miles for the last 2 months. This has caused serious inconvenience to me, as bicycle is my preferred mode of transport to work and class. Details of the situation:

  1. Hybrid bycicle (specialized Globe 2007 -- 5,000 miles ballpark on it)

  2. Only rear wheel is flatting

  3. Rear wheel is 622x19C rim

  4. Tire is 700x35, Kenda 700 35-42 inner tube

  5. I just replaced the whole rim and spokes, for $60 (I had a lot of broken spokes and the rim was out of alignment badly). However the flats keep coming.

  6. Tire pressure suggested on the rear wheel is 30-60 PSI

  7. I run the pressure between 50-60 PSI

  8. I weigh 212lbs. and I carry up to 30 extra pounds of load (backpack etc.)

  9. The holes in the inner tube are usually single tiny punctures.

  10. I never find anything in the tire like glass or anything

  11. The tire seems to have been worn very quickly (it seems kind of like a cheap tire).

Is the tire a possible cause, or is it possible that some misalignment in the hub (Shimano attached to an 8 speed cassette) is just messing things up?

This is driving me crazy... maybe I should buy a new tire and run the pressure much higher?

Run the pressure lower? buy some specialized kind of inner tube?

I would really do anything to avoid having to patch flats every other day!

THANKS EVERYBODY, I BOUGHT AN ARMADILLO FROM SPECIALIZED... NO FLATS IN 2 WEEKS ** I think the pressure was way too low on the piece of crap tire i had before ... armadillo is solid!!

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another reason that tires go flat sometimes is because of insufficient/nonexistant spoke protector on the inside of the rim - the end of a spoke is sharp enough to flat a tube –  Nate Koppenhaver Nov 12 '11 at 18:52

7 Answers 7

up vote 8 down vote accepted

Are the holes always on the tread side of the tube? Do you often go over curbs or other large bumps with the bike? The possibilities are:

  1. you're damaging the tube when you change/patch it
  2. you're running over a lot of thorns/tacks
  3. you're getting "snakebite" flats from running the pressure too low
  4. someone has it in for you and is "helping" the tire go flat

In any event, for that much weight on a road bike 60psi is the minimum you should be running -- I run 90-100 on my 700C-35s. You should get Kevlar-belted tires -- much more puncture resistant -- and get tires that are rated to run at least 80psi. And I'm wondering if 35s aren't a hair wide for 19 rims -- that may be contributing to snakebite punctures.

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thanks! are you saying perhaps that 32's are the way to go? –  Bozostein Oct 30 '11 at 13:46
    
and as regards #4 I actually thought this might be possible but looking at the timing I am pretty sure the flat is occurring during my ride to work (10 miles) or so. –  Bozostein Oct 30 '11 at 16:39
1  
I'm just saying that the rims are a hair narrow, and that would contribute to "snakebite" style punctures, where the tube is damaged when it's pinched while hitting a curb or other large bump. You can generally tell snakebite punctures from the holes -- they often come in pairs, one on the outside diameter and a matching one on the inside (hence "snakebite"), positioned off-center such that they are over the rim edge. –  Daniel R Hicks Oct 30 '11 at 18:34
    
+1 on kevlar belted tires. I've had good experiences with panaracer RIBMO tires (or any of their PT line) and vittoria Randoneer tires. I've also heard good things about continental gatorskins. All of those should be available in a 700x35 size (and many others) –  Benzo Jun 1 '12 at 17:21

First thing I'd check is your rim tape if you cant find anything along the tire itself. Next time you get a flat, when you're taking the tire off, find a common spot along the tire and the tube - for instance, I typically put the tire's logo next to the valve. This way, you can narrow down the area of where to look for trouble.

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Right. When you pull the tube out always try to keep the orientation straight so you can check the inside of the tire at the spot when the hole in the tube is. And, if the hole is on the inside diameter of the tube strongly suspect a spoke poking through the rim tape. The location of the hole in the tube is a big clue. –  Daniel R Hicks Oct 30 '11 at 3:03
    
thanks for the advice! –  Bozostein Oct 30 '11 at 13:46

It's possible there's something stuck in your tyre that you can't find but when riding it is puncturing the tube. I've had the same situation and replacing the tyre completely fixed it.

If you wanted to gather some evidence you can check if all the flats are happening in the same place relative to the tyre position.

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1  
If they are happening in the same place, hunt really hard for a tiny object poking through. Sometimes things can be just about invisible to the eye, but if you feel around with your finger you'll find it. It can also help to turn the tire inside out to expose it more. –  Jefromi Oct 30 '11 at 5:55
    
It helps to actually patch your tubes rather than just replacing them. (Swap in your spare and patch it at home.) Then, if the hole keeps occurring in the same place (or symmetrically opposite relative to the stem) you'll notice it. –  Daniel R Hicks Oct 30 '11 at 12:27
    
thanks for the advice!... I ordered an armadillo... i think that may help... –  Bozostein Oct 30 '11 at 13:45

I started with 700x32 Continental Contact tires for commuting (I weigh 165 lb).

I kept them inflated but I got 3 flats in the first 6 months / 3000 miles: all (perhaps unusually) on the front wheel. The first was a roofing nail through the tire; the second was a shard of glass, and again the next day when they hadn't taken the shard glass out of the tire before putting in a new tube.

I've replaced those tires with Schwalbe Marathon Plus, and don't expect more punctures. I inflate them to 85 psi, once or twice a week, and ride two hours / weekday.

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This doesn't directly answer the question (you've gotten some good advice in this thread already), but a trick worth learning is to always mount your tire with the manufacturer's label (or some visual landmark) in line with the valve.

That way, when you find the puncture in your innertube, you can work back to where the tire was punctured (assuming the puncture is on the tire side, not the rim side). Sometimes there's a tiny chip of glass or tire cord embedded in the tire carcass—it can be hard to find even if you know where to look, but it's impossible if you don't, and as long as it's in there, it can keep causing flats.

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interesting i found a chip of glass actually recently after one of my flats-- it looks so innocent after the tire is deflated ( like how could that possible go through the tire ... but i think this was it... –  Bozostein Oct 30 '11 at 22:33
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Another good trick - assuming you've done the above - is to inflate the "flat" tube once it's out of the tire. It'll blow up like a balloon, but it becomes easier to find the hole; you'll hear the air escaping. Once you've found the hole, use the above tip to find the piece of glass/thorn/whatever that's in the tire. –  Neil Fein Oct 30 '11 at 22:40
2  
Neil points out a good technique for bit and small punctures. For the leaks I can't readily spot, I keep a bottle of foaming hand soap next to my bike tools. I get a cup of water, dab my hands wet and soap up the tire when inflated. The culprit will bubble...the bubble grows rather slowly in the case of a slow leak. –  memnoch_proxy Oct 31 '11 at 3:43
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Right. And in those situations where you can't lay your hands on a basin of water or soap, I've found that the best way to find a subtle leak is to inflate the tube and rotate the tire around until I get the leak to expel air onto my lips--they're more sensitive than anything else, and will pick up jets of air you'd otherwise miss. –  Adam Rice Oct 31 '11 at 15:08
    
I would slowly pass the tire past my ear, but small leaks often sound similar to the sound of the inner tube rubbing against my whiskers :-) –  memnoch_proxy Oct 31 '11 at 22:09

By your description, specifically the holes being consistently just tiny punctures, probably you are having a problem with thorns or, most likely, tire wires (the metal scrap that damaged truck tires use to leave around.)

It is very important, in order to detect the cause and avoid repeated punctures, to examine carefully, with the bare fingertips, all the inner part of the tire to find sharp stuff stuck in the tire. I do this all the time and never got hurt. As others mentioned, check if the punctures are in the "inner (rim)" or "outer (tire)" side of the tube.

I live near a park with thorny trees, and riding there is a problem, since the thorns tend to puncture the tires easily. Sometimes they get stuck in the tire, so you can find the culprit, but sometimes they do not, so the mistery might remain.

On the road, by far the culprits are the truck-tire-metal-scrap stuff (much more than glass, in my experience), but these get usually trapped in the bike tires, sometimes deceitfully. You have to look carefully.

Nowadays there are a lot of tire brands with puncture protection embedded in the thread, like Schwalbe, Continental, Maxxis and Specialized that I remember. Also, the rubber in these tires is of better quality. They pay themselves.

Another option would be to use protective tape (Mr. Tuff and the like) inside the tires. They are relatively expensive, but pay themselves in tubes and time you won't waste. For skinnier tires, this is the best option I think.

Hope it helps!

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I've had repeated flats in the past, and the culprit turned out to be one of:

  1. Crud (tiny glass shards, rocks, etc.) embedded in the tire itself. The way to solve this is to carefully inspect the tire inside and out and remove the debris. This includes prying open each small crack or hole to see if there is debris still inside. (Also an excellent preventative measure.)

  2. Crud inside the tire (i.e., between the tire and the tube). The way to solve this is to (carefully, since these things can be sharp) examine the inside of the tire, perhaps by feel, to locate and remove all debris. I often wipe out the tire with a kerchief or something before putting the new tube in.

Finally, as others have noted, quality tires help a lot. You want tires designed for durability, not speed.

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