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Tube bulge: safe or not safe?

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Tube bulge: safe or not safe?

Old 03-07-18, 11:49 AM
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Coasterbrakefan
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Tube bulge: safe or not safe?

While patching and rolling some tubes, I came across one that when inflated, (outside of the tyre) a section of the tube expands to around double the size of the rest of the tube.

Scary.

Understandably, I could ditch the tube and buy another for $5, but I was simply curious as to whether or not the tube is safe to use.

Also, what causes this? Defect? The tube is off of a second hand bike.

Cheers
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Old 03-07-18, 11:51 AM
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Omg!
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Old 03-07-18, 11:53 AM
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Originally Posted by Coasterbrakefan View Post
While patching and rolling some tubes, I came across one that when inflated, (outside of the tyre) a section of the tube expands to around double the size of the rest of the tube.

Scary.

Understandably, I could ditch the tube and buy another for $5, but I was simply curious as to whether or not the tube is safe to use.

Also, what causes this? Defect? The tube is off of a second hand bike.

Cheers
It's a thin spot in the rubber.Probably the top of the mold it was made in.
I'd go ahead and use it.
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Old 03-07-18, 11:58 AM
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does it pass the No- bubble test , submerged in water?
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Old 03-07-18, 12:04 PM
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Not at all uncommon - just a minor variation in the thickness of the rubber. As long as it holds air go ahead and use it.
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Old 03-07-18, 02:53 PM
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Common. No biggie.
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Old 03-07-18, 02:54 PM
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It can't bulge inside of the tire.
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Old 03-07-18, 02:55 PM
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You will probably find that every tube you use will do this to some extent.
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Old 03-07-18, 03:03 PM
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You'll have a lot less of a bulge if you put it inside of a tire when mounting on your bike.

The biggest issue isn't the big bulges like you found, but rather micro-bulges from sagging bad rim tape. And these nipple hole bulges can cause flats, although not necessarily a catastrophic failure. Flats are part of riding.
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Old 03-07-18, 08:24 PM
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How is the tube ever going to bulge that much when mounted inside a tire? If nothing else many tubes will bulge either next to the stem, where the reinforcement constricts it, or where the tube was joined during manufacturing.
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Old 03-08-18, 05:44 PM
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Well I'm seeing an all around a-okay, so I'll keep it. Thanks everyone!
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Old 03-08-18, 07:03 PM
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Originally Posted by Coasterbrakefan View Post
Well I'm seeing an all around a-okay, so I'll keep it. Thanks everyone!
Yep, they all do it to some extent, depending on the pressure. If you pump enough air into them you can get the tube to look like a python that ate an elephant before it explodes.
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Old 03-13-18, 12:26 PM
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Tubes have very little structural strength, they rely on the tire to provide that.
They’ll expand until the tire stops them. It is very common for tubes inflated outside the tire to look like cartoon drawings of recently fed snakes.
I guess it’s possible that it can get extreme enough to cause an issue, but I’ve never encountered it.
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