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Pinching tube during install

Old 05-01-15, 10:19 AM
  #1  
hazben1
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Pinching tube during install

I have had a lot of trouble with flats lately and am beginning to wonder if my install technique is partially to blame. I very slightly inflate the tube, then put it inside the tire,then I put the tire bead over the rim. I do not use levers to do this just hand pressure. At times the tube may get slightly stuck/pinched between the rim and the tire bead as the bead gets pushed over the rim. Before I fully inflate the tube I go around the tire on both sides pulling the tire away from the rim to be sure it is all the way in the tire and not pinched between the tire and rim. When I am installing the tube and it gets slightly pinched between the tire and bead I am damaging the tube even though it is not inflated? The tire inflates fine but within a few days or week I have a flat. Any ideas?
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Old 05-01-15, 10:31 AM
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I'm paranoid of getting a second flat while out riding, so I check the entire bead on both sides of the tire for tube sticking out too. Never had a blow out flat from having tube sticking out past the bead.

Do you always check to figure out the cause of your flats? It's almost always road debris puncturing the tube for me. Once I missed a radial tire wire stuck in the tire and the replacement tube held up for a couple of days but was imperceptibly going flat.
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Old 05-01-15, 10:32 AM
  #3  
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The fact that it's a matter of days or a week before it flats suggests that it's not related to how you mounted. Your technique is basically OK, and it's not likely hat you pinched the tube installing without tools.

Two suggestions that might help, though I don't think it's a big deal.

1 - stuff the tube deeper into the tie so it's not near the bead or rim when you push the tire over. If you have tubes that are a bit short and pull down near the end, especially with a tight tire, use a tire lever to push the tube deeper into the tire, but not to lever against the rim which might cause a pinch.

2- start mounting the second side opposite the valve and end at the valve. The valve can help you by keeping that end section of tube from pulling down between the tire and rim, and when finished you can push the valve in to clear any tube that might have been trapped under that last section of bead.

So, I suspect that you might be getting classic "snake bite" punctures which happen when the tire is pressed all the way down to the rim trapping and crushing a fold of tube. These are the result of sharp edged potholes or driveways, hit with low pressure in the tire.

One way to tell is that snakebites are almost a double cut since the tube was folded when trapped, which is how they got the name. Pinches from installation are usually a single cut, or if double the cuts may be larger or farther from each other.
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Old 05-01-15, 12:14 PM
  #4  
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Are these flats punctures? If so, where (on the tube) are the punctures? What shape and size are the punctures?
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Old 05-01-15, 01:25 PM
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Originally Posted by AnkleWork View Post
Are these flats punctures? If so, where (on the tube) are the punctures? What shape and size are the punctures?
Yep, the type of flat will almost always tell you what is going on.
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Old 05-01-15, 01:40 PM
  #6  
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Also, you need to make certain that you have eliminated the cause of the original puncture. Lining up the valve stem of the tube with the label on the tire is a common way to isolate the spot on the tire that matches the hole in the tube- check carefully- there are lots of things that can cause a flat that are ridiculously tiny and can remain lodged in the casing of the tire.
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Old 05-01-15, 02:28 PM
  #7  
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The worst culprit is the radial tire wire that gets deposited on the road when big truck tire fail. They can be hard to find. Next time you see that the tire has lost air in a short amount of time, over inflate it and submerge it in water to find the leak.
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Old 05-01-15, 02:54 PM
  #8  
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Can't say if your pinched tube is the reason for your flats, but if you want to eliminate pinching tubes, get one of these...



VAR RP42500

I still have an old one from the 80's, but picked up a couple more. They work great for those horrible rim/tire combos that just don't want to easily go on by hand.

John
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Old 05-04-15, 07:54 AM
  #9  
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Sorry I have not got back to my question. My bike time has been getting in the way of my computer time. Thanks, for the ideas. I yet again got another flat this past Saturday. I did 70 Sunday with no issues. These are not pinch flats although I did get one because the 16g co2 cartridge did not fill my 25mm tire up quite enough and due to the way my luck has been going with flats I did not want to use my last co2 to put more air into it. On the road I check the inside of the tire carefully for potential issues and have not found any. On the road I don't try to find exactly where the puncture is because I don't want to use up any more of my 3 co2 cartridges. I am working on replacing my minipump which I had been carrying with me on all rides along with the co2.

I know what you mean about the tiny bits of wire you pick up from car tires. I have had to deal with those several times in the past. When I get back from my ride I have started inflating the tubes to figure out exactly where the puncture is. Next I have started marking on the tire where it was and searching very closely for imbedded debris. Have not found anything. I also mark the tire where the puncture was to see if I am getting punctures in the same place. So far that is not the case. Last Monday my flat was while on the rollers. So I feel it has to be something with the tire, tube or wheel. I will say this past Saturday when I was changing my tube on the side of the road I did find a small piece of debris inside the tire. It didn't seem that hard or sharp. But, maybe it is what was causing the flats.
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Old 05-04-15, 08:00 AM
  #10  
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Try rubbing a cotton ball on the inside of the tire, it may catch something poking into it. Take the tire off the rim. Carefully inspect anycut with a awl to see if something is stuck in it. Feel the entire inside of the tire for debris. Start there.
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Old 05-04-15, 09:08 AM
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But if you don't find the cause of the first flat, you will surely get a second. And what does finding the cause have to do with using an additional cartridge? You don't use the cartridge to find the hole. That's what eyes and fingers are for.
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Old 05-04-15, 11:00 AM
  #12  
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Originally Posted by demoncyclist View Post
But if you don't find the cause of the first flat, you will surely get a second. And what does finding the cause have to do with using an additional cartridge? You don't use the cartridge to find the hole. That's what eyes and fingers are for.
On the road for me to find the puncture in the tube I would probably have to air up the tube. As far as looking for the cause of the puncture I am pretty diligent looking and feeling on the inside of the tire for what may have caused the puncture.
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Old 05-04-15, 11:08 AM
  #13  
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I take the whole tire off, inflate the tube just enough to fit it inside the tire, put tire back on one bead, then do next bead. This really ensures the tube to be nice and round. It takes a slightly longer time but works real well. And I know out being on the road you want to do it quickly but just a minute longer is worth it so you don't get a pinch flat again a mile down the road.
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Old 05-04-15, 11:19 AM
  #14  
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Update, I aired up all the tubes (8) and marked the punctures. The first 3-4 punctures I had gotten I had not bothered marking on the tire where the puncture occurred. Sure enough the puncture Saturday and the first 4 from weeks ago were all in roughly the same spot on the tire. Took the tire off and went to good light source and turned the tire inside out where the punctures were occurring. Went over with cotton wool and got nothing. Looked with magnifier and I could see where indeed something had gone all the way thru the tire. Bent the tire over on the inside cut but could not feel or see anything? The other 3 punctures I really can't explain.


At this point I am not real sure what to do. I am inclined to attach a tube patch inside the tire. I am guessing I will not notice any drivability issue with a patch on the inside of the tire. Any other ideas? I will probably also move this tire to the front wheel where there is less weight.
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Old 05-04-15, 11:28 AM
  #15  
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Leave that one in the back- a blowout is much easier to deal with if it isn't the front wheel, which can cause you to lose control of the bike. You can "boot" that spot in the tire and continue to ride it. But, if the cords in the casing are badly damaged, replacement with a better constructed tire- even something with a kevlar belt or other flat-reduction technology would be the way to go. Also, if you are using Presta valves, you can sometimes inflate to a low pressure by mouth.
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Old 05-04-15, 11:40 AM
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Originally Posted by demoncyclist View Post
Leave that one in the back- a blowout is much easier to deal with if it isn't the front wheel, which can cause you to lose control of the bike. You can "boot" that spot in the tire and continue to ride it. But, if the cords in the casing are badly damaged, replacement with a better constructed tire- even something with a kevlar belt or other flat-reduction technology would be the way to go. Also, if you are using Presta valves, you can sometimes inflate to a low pressure by mouth.
When I install a tube on the road I blow up the tube by mouth to make installation easier. I certainly understand about rather having a blowout on the back rather than the front. But, when this deflates it is rather slow and with a boot I think it is even less likely to blowout. As far as a better quality tire I have used many different tires and have come to really like the Cont. GP4000s II. I supposed I could go with the Gatorskins but up until this current episode I have not had too much issuer with flats.
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Old 05-05-15, 10:21 AM
  #17  
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Originally Posted by Leebo View Post
Try rubbing a cotton ball on the inside of the tire, it may catch something poking into it.
Good. If that doesn't find the culprit, turn the tire casing inside out, and do the cotton ball thing in both directions. If there is a wire embedded i nthe tire casing, this will find it.
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Old 05-05-15, 12:06 PM
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Originally Posted by demoncyclist View Post
Also, you need to make certain that you have eliminated the cause of the original puncture. Lining up the valve stem of the tube with the label on the tire is a common way to isolate the spot on the tire that matches the hole in the tube- check carefully- there are lots of things that can cause a flat that are ridiculously tiny and can remain lodged in the casing of the tire.
What kind of rim strips do you have?

Lots of bikes today come with some stretchy plastic rim strips. If they are on the narrow side they can migrate over to the side of the rim and expose a spoke hole. It only takes the tiniest arc of exposed spoke hole to cut the inside circumference of your inner tube,
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Old 05-05-15, 12:57 PM
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^^this^^
you may need new rim tape.
happened to me last year...brand new tires and tubes.
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Old 05-07-15, 01:17 PM
  #20  
hazben1
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Originally Posted by Retro Grouch View Post
What kind of rim strips do you have?

Lots of bikes today come with some stretchy plastic rim strips. If they are on the narrow side they can migrate over to the side of the rim and expose a spoke hole. It only takes the tiniest arc of exposed spoke hole to cut the inside circumference of your inner tube,
I do have the cheap stretchy plastic strips. Last year I got 2 punctures in a rather short time due to the tape being shifted to the side slightly. Now I check the rim tape whenever I have a flat. For now I put a patch on the tire and will wait to see what happens. It does bother me though not being able to find what did cause those 4 punctures in the same spot. Did 70 miles yesterday without any problems. Maybe whatever it was fell out the tire without me seeing it.

Thanks to all those who gave me input, this has been a learning experience for me. I am going to be more diligent in finding the cause of a puncture the first time it happens. Time for me to buy another minipump..
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Old 05-07-15, 03:06 PM
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Get rid of those rim strips and replace with Velox tape!!!
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Old 05-07-15, 04:38 PM
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after 30 years of cycling it just happened to me yesterday. Dumb.
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