Keep getting blow outs !!
09-30-13, 02:53 PM
#1
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Keep getting blow outs !!
Im at my wits end , my whote bike keeps getting blow outs i fill tires to 100PSI ride all day and then bike just sitting there tube just pops , front and rear I ve so much money in tubes i could have bought another bike probably . I have checked the inside of tires and there is nothing puncturing the tube and it seems that they keep blowing up right by where the stem is, I know its not defective tubes as I have bought them from diff places and brands. has anyone had this issue ? Could it be that im overinflating ? tire says max psi is 110 . Tire is 700/25 60mm stem
Need help w this .
Thanks
Need help w this .
Thanks
09-30-13, 03:08 PM
#2
SuperGimp
How are you pumping the tires up? What kind of pump and does it have a flexible hose?
My guess would be you have a rough spot around the valve stem, or your rim tape is bad, or you are damaging the stem when you inflate the tire.
Does your rim have any deformations around the area of your stem? Are the blown out areas consistently in the same spot and do they look the same?
My guess would be you have a rough spot around the valve stem, or your rim tape is bad, or you are damaging the stem when you inflate the tire.
Does your rim have any deformations around the area of your stem? Are the blown out areas consistently in the same spot and do they look the same?
09-30-13, 03:10 PM
#3
Mechanic/Tourist
First, blowout is usually used to describe an explosive loss of air - BANG! In almost all those circumstances the tube has to escape the confines of the tire, and the resulting hole will be star-shaped or a long split in the tube. If that is what you are getting you are catching part of the tube underneath the tire bead. After a while the tube will push the bead up enough for the tube to briefly escape. After the blowout the tube often is back inside the tire.
If you are merely getting holes next to the valve that is not a blowout. It may be due to the tube having to fill up too much space next to the valve where it goes through the rim. As FBinNY has described it in detail before I found one of his posts about the subject.
This applies mainly to narrow rims, most often when combined with wide tires. A key factor is the inside width of the rim and the thickness (not width) of the tire at the bead. Thick beads on narrow rims leave only a narrow gap between them inside the rim, so the air chamber is sort of hourglass shaped with a circular section in the tire, the pinch, and another space below it within the rim.
When you inflate the tube, it first fills the space inside the tire, then the narrow section at the bottom blows down past the pinch filling the area in the rim. That means that this section of the tube may stretch 2-4 times more than the rest of the tube, hyperstretching it and often splitting or tearing it. You'll often see the results of this hyperstretching along the underside of the tube.
There's no easy fix, but these have been known to help.
Use the largest tube that fits, so there's more room to stretch
Rub talc on the inside of the tire, and outside of the tube, to allow the tube to shift more easily.
Inflate the tire only to a few psi and massage it to try to let the tube shift down.
Inflate the tube outside the tire to about double it's size (look for quality tubes that expand evenly, rather than crappy ones that inflate in small sections the way long balloon do). Let the tube stay this way overnight to relax the material a bit.
Inflate part way and leave the wheel alone for a while before coming to full pressure.
Hand stretch the tube, as many do with balloons to relax the material.
Warm the tube slightly (in the sun, or under a heat lamp) to make it stretchier.
I make no claims to precise science here, but I've helped lots of friends with similar issues, and with one or more of the above all have managed to put this behind them. Some may only be voodoo, but if it solves the problem I don't worry about exactly why or how. Part of me believes that the biggest factor is the tubes overall quality, and the rest may be like banging sticks together to keep the lions away.
If you are merely getting holes next to the valve that is not a blowout. It may be due to the tube having to fill up too much space next to the valve where it goes through the rim. As FBinNY has described it in detail before I found one of his posts about the subject.
This applies mainly to narrow rims, most often when combined with wide tires. A key factor is the inside width of the rim and the thickness (not width) of the tire at the bead. Thick beads on narrow rims leave only a narrow gap between them inside the rim, so the air chamber is sort of hourglass shaped with a circular section in the tire, the pinch, and another space below it within the rim.
When you inflate the tube, it first fills the space inside the tire, then the narrow section at the bottom blows down past the pinch filling the area in the rim. That means that this section of the tube may stretch 2-4 times more than the rest of the tube, hyperstretching it and often splitting or tearing it. You'll often see the results of this hyperstretching along the underside of the tube.
There's no easy fix, but these have been known to help.
Use the largest tube that fits, so there's more room to stretch
Rub talc on the inside of the tire, and outside of the tube, to allow the tube to shift more easily.
Inflate the tire only to a few psi and massage it to try to let the tube shift down.
Inflate the tube outside the tire to about double it's size (look for quality tubes that expand evenly, rather than crappy ones that inflate in small sections the way long balloon do). Let the tube stay this way overnight to relax the material a bit.
Inflate part way and leave the wheel alone for a while before coming to full pressure.
Hand stretch the tube, as many do with balloons to relax the material.
Warm the tube slightly (in the sun, or under a heat lamp) to make it stretchier.
I make no claims to precise science here, but I've helped lots of friends with similar issues, and with one or more of the above all have managed to put this behind them. Some may only be voodoo, but if it solves the problem I don't worry about exactly why or how. Part of me believes that the biggest factor is the tubes overall quality, and the rest may be like banging sticks together to keep the lions away.
09-30-13, 04:22 PM
#4
Really Old Senior Member
When initially installing the tube-
Add about 5-10 PSI and then let it all out.
Repeat.
This allows the tube to "settle out", incase you have any folds etc.
You aren't using a Schraeder valve in a Presta hole by chance?
Add about 5-10 PSI and then let it all out.
Repeat.
This allows the tube to "settle out", incase you have any folds etc.
You aren't using a Schraeder valve in a Presta hole by chance?
09-30-13, 04:24 PM
#5
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Im using hand pump, i dont think im pinching the tube as I m able to use it for a dfay or so and then all of the sudden it just blows out , its not loosing air gradually it just blows out.
09-30-13, 04:25 PM
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No not at all, I ve done all it just keeps happening, I even took the rim to LBS and let them do it and bam it happened just now .
09-30-13, 04:54 PM
#7
Banned
make sure , by going around the tire and looking, to see that no part of the tube is not between the tire beads .
and none is remaining under them, .. the bit under, lifts the tire up over the edge of the rim,
and there, typically, is your blow-out.
[other than the casing side wall of the tire failing.]
and none is remaining under them, .. the bit under, lifts the tire up over the edge of the rim,
and there, typically, is your blow-out.
[other than the casing side wall of the tire failing.]
09-30-13, 05:19 PM
#8
Mechanic/Tourist
What exactly does the hole/puncture look like, what is the width of the inside of the rim, and what size tire are you using?
09-30-13, 05:37 PM
#9
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Does the tube size match the tire size? Check the stem hole to make sure there are no sharp edges
09-30-13, 05:39 PM
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The hole its usually about 1 Inch in lenght its usually in the general stem area within 2 to 4 inches from it , the 1st time it happened i was ridding and i stopped for a break and it popped , and its been downhill from there its either front or rear they just keep taking turns, lol!!! yesterday I filled up rear to 100 psi and 2 minutes later it blew so i replaced it , my son called me earlier today he was just sitting in living room and said the front did the same thing . damn bike must be haunted
09-30-13, 05:52 PM
#12
Mechanic/Tourist
I've been dropping in briefly, so I'm not being as throrough as I should be.
First some observations - It's very unlikely anything to do with rim or tire damage, as it's happening on both tires. The distance of the from the stem and that it seems to be a split, rather than a hole. means it's not the problem that FBinNY explained.
Something out of the ordinary must be happening for two tires to repeatedly be having the same problem, and it is most likely something to do with you, as this degree of problem is very unusual, and thousands of people have the same tires, tubes or rims.
In spite of the fact that you think you have not pinched the tube it is the most likely cause, unless you recently purchased tires and they are both from a defective batch (unlikely). Still need inside width of the rim and the tire size - tube size as well if it's marked.
Other info needed (Please provide all the info requested, not just what you think is relevent):
How long have you had the bike?
When did the problems start?
Did you make any changes just before the problem started?
Thanks
First some observations - It's very unlikely anything to do with rim or tire damage, as it's happening on both tires. The distance of the from the stem and that it seems to be a split, rather than a hole. means it's not the problem that FBinNY explained.
Something out of the ordinary must be happening for two tires to repeatedly be having the same problem, and it is most likely something to do with you, as this degree of problem is very unusual, and thousands of people have the same tires, tubes or rims.
In spite of the fact that you think you have not pinched the tube it is the most likely cause, unless you recently purchased tires and they are both from a defective batch (unlikely). Still need inside width of the rim and the tire size - tube size as well if it's marked.
Other info needed (Please provide all the info requested, not just what you think is relevent):
How long have you had the bike?
When did the problems start?
Did you make any changes just before the problem started?
Thanks
Last edited by cny-bikeman; 09-30-13 at 06:01 PM.
09-30-13, 05:57 PM
#13
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If you still have a few tubes, take a careful look along the belly (rim side). I'll venture that there are "stretch" or patches that are stretched out of the normal shape of the tube at various points. This is becoming more common as folks use narrower rims and tires. (or wide tires on narrow rims)
When a tire is mounted (see sketch) there's a sort of hourglass shape, with the tire above, then a narrow area between the beads (3), and the space inside the rim below the beads.
As you fill the tire, the properly positioned tube fills the tire at about 5psi, spanning the narrows. With more pressure, the section across the narrows blows down into the space below. Since the tube is sticking against the tire, only the narrow section expands, so it's effectively stretched 2-3x the rest of the tube. The end result is that this hyper-stretched section can burst, just like an overinflated balloon.
The reason you're getting these blowouts near the valve is because the tube is reinforced at the valve, and that thicker area doesn't blow down down through the narrows, so the nearest unreinforced section suffers more, and stretches more because it's blowing back toward the valve.
Here's the fix. Mount the tires starting opposite, and ending at the valve. When finished, push the valve in to make sure the tube is well inside the tire, and not trapped under the bead. Carefully pull the valve back out and try to massage it all the way down past the narrows. Inflate to about 5psi, and check tire seating, then inflate slowly to full pressure.
Other things that people say helps.
Powdering the tube very thoroughly so it's slipperier and can slide along the tire as it blows down through the narrows.
Resting the tire inflated to about 20psi, so the tube can spread out more evenly.
Adding about 5" of electrical tape along the belly centered at the valve. This makes it more slippery and helps the transition past the reinforced section.
When a tire is mounted (see sketch) there's a sort of hourglass shape, with the tire above, then a narrow area between the beads (3), and the space inside the rim below the beads.
As you fill the tire, the properly positioned tube fills the tire at about 5psi, spanning the narrows. With more pressure, the section across the narrows blows down into the space below. Since the tube is sticking against the tire, only the narrow section expands, so it's effectively stretched 2-3x the rest of the tube. The end result is that this hyper-stretched section can burst, just like an overinflated balloon.
The reason you're getting these blowouts near the valve is because the tube is reinforced at the valve, and that thicker area doesn't blow down down through the narrows, so the nearest unreinforced section suffers more, and stretches more because it's blowing back toward the valve.
Here's the fix. Mount the tires starting opposite, and ending at the valve. When finished, push the valve in to make sure the tube is well inside the tire, and not trapped under the bead. Carefully pull the valve back out and try to massage it all the way down past the narrows. Inflate to about 5psi, and check tire seating, then inflate slowly to full pressure.
Other things that people say helps.
Powdering the tube very thoroughly so it's slipperier and can slide along the tire as it blows down through the narrows.
Resting the tire inflated to about 20psi, so the tube can spread out more evenly.
Adding about 5" of electrical tape along the belly centered at the valve. This makes it more slippery and helps the transition past the reinforced section.
__________________
FB
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An ounce of diagnosis is worth a pound of cure.
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FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
Last edited by FBinNY; 09-30-13 at 06:20 PM.
09-30-13, 06:14 PM
#14
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After mounting the tire and tube and before inflating, push the valve stem into the tire and make sure the tire bead in the area of the valve stem is seating properly. Often the part of the tube at the base of the stem gets in the way of the tire bead and keeps it from seating. Pushing the valve into the tire will allow the bead to seat. This type of problem can cause a delayed blowout.
