What's The Best Way To Figure Out What's Popping My Inner Tube?



JoanMcWench

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Feb 17, 2015
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I have a mountain bike that I've had to replace the inner tube quite a few times. I thought that the issue was in the tire itself (like perhaps a small shard of glass) so I ran a cloth inside the tire & could not find the culprit. Can the issue be my rim? That's one aspect I didn't really inspect. Any other things I should troubleshoot?
 
Pinch flats? Where do you get the punctures? Rim side? Sidewall? Tread side?
 
Top side. Which is why I assumed it had something to do with there being something embedded in the tire & it's like a pin hole in size.
 
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Run your hand on the inside of the tire, gently. If there's something sharp in there, you don't want to get blood all over your wheel. If you don't feel anything, try again, with more aggressiveness.

If this doesn't turn up anything, examine the outside. Poke at anything that looks like a projectile with tweezer or a sharp instrument, like a dental pick. Whatever you find, pull it out.
 
BTW. If you are having trouble feeling the possible protrusion inside the tire's casing with your bare hands then try wiping a dry cotton ball across the area where you think the intrusion into the tire is occurring.
 
When you mount the tire, align the manufacturer information with the valve. That way, when the tube breaks and you figure out where the hole in the tube is, you can also figure out where the corresponding location in the tire is - you'll have two possibilities.

Then you can concentrate your search effort in those areas of the tire - sometimes the cause is very small and difficult to see, but if the tube keeps gets a hole on the road side, something will be there.
 
alfeng said:
BTW. If you are having trouble feeling the possible protrusion inside the tire's casing with your bare hands then try wiping a dry cotton ball across the area where you think the intrusion into the tire is occurring.
Is the cotton ball much different than using a rag? I use the rag to see if it catches the snag of whatever may be embedded.


Yojimbo_ said:
When you mount the tire, align the manufacturer information with the valve. That way, when the tube breaks and you figure out where the hole in the tube is, you can also figure out where the corresponding location in the tire is - you'll have two possibilities.

Then you can concentrate your search effort in those areas of the tire - sometimes the cause is very small and difficult to see, but if the tube keeps gets a hole on the road side, something will be there.
Didn't even think of that. Thanks.
 
The cotton ball will "trail off" lint when hung by the sticky that's messing up your tube, thus telling on the cause.

If you allign the label with the valve, it will also tell you if the ***** keeps happening in the same spot. (VERY useful info.)
 
JoanMcWench said:
Top side. Which is why I assumed it had something to do with there being something embedded in the tire & it's like a pin hole in size.
Top side? If you mean the top side of the tube, check your rim tape. The end of a spoke may be protruding through the tape. Try having your shop line the rim with Velox tape.

If you mean the tread side, ie, "top" side of the tire, you almost certainly have a small, fine foreign object embedded in it that's sticking through the tire. Maybe a small, fine piece of wire.
 
I guess we need clarification on that as there is no "top" or "bottom." Is it inside (spokes) or outside (tread)?
 
Outside. I meant top as in when it's aligned on the rim. Which is why I thought something was in the tire. It's definitely small & seemingly invisible. I'm starting to think I'm crazy. Might have to take it in. Hate when I can't fix it myself.
 
JoanMcWench said:
Outside. I meant top as in when it's aligned on the rim. Which is why I thought something was in the tire. It's definitely small & seemingly invisible. I'm starting to think I'm crazy. Might have to take it in. Hate when I can't fix it myself.
Wait ...

What?

Are you saying that "aligned on the rim" means that it is on the rim side of the tube and not the road side?

If THAT is the case where the problem is on the inner circumference of the tube, then I would suggest that the problem is more-than-likely due to a faulty rim tape ...

  • there are SOME woven rim tapes which are not robust enough (for various reasons) to prevent the inflated tube from making contact with the ends of the spokes ...
    wrapping CLEAR packing tape (cut to width) on top of the woven tape is a short-term remedy ...

[*]sometimes, the rim tape is too narrow for the bed & doesn't stay centered which will then allows the tube to make contact with the end of the spoke ...
[*]I have seen people use stranded packing tape which eventually fails & subsequently allows the tube to make contact with the end of the spoke
The cheap OEM rim-tape in the old days was cut from old inner tubes ...

VELOX is a never-fail brand of rim tape ...

PEDRO used to (and, may still) sell a fairly robust, woven rim tape.
 
When you get a reoccurring flat and you can't find the offending 'pokey' item with ease, pull the inner tube out carefully and keep the alignment the same as it was when in the wheel. Inflate slightly and find the hole in the inner tube. Lay it on top of the wheel while the wheel is on its side. You'll find exactly where you need to look.

Of course, it's important that you keep the wheel and innertube aligned the same as they where when you removed the innertube. If you alter one you're kinda farked.

If you see a cut in the outside of the tire then squeeze the tire together to open up the cut so you can see if there's a shard of something inside.
 
You might want to have someone at a shop take a good look at it. They might be more experienced at finding problems like that. Have you been using any tire guards? I had them once because someone recommended them, but found out later that the edges of the guard were actually causing me more problems. My regular shop stopped selling them because of that.
 
I always align the drive side brand label on my tire at the valve, when I mount a tire (drive side because some tires have offset labels). This way, even if the tire moves while you're removing the tube, or you decide to pull the whole tire, you can re-set it to help find anything in the tire/rim that's causing the puncture.

Just remember which side of the front wheel was the drive side, if the tire has offset labels. ^_^
 
I'm still lost as far as where the hole is. Joan McWrench, can you please either say it's in the tread, or the spokes? There is no "top" or "bottom" to a tire. It is constantly turning over, literally.

If I start having trouble out of a tire, I will put a mark on the tire, even if it's with a magic marker. You have to look closely, but I can see black magic marker writing on a black tire. ...then again, there's always Krylon. Put a paint dot so far from the label.
 
By top or bottom I'm referring to the bottom being where the inner tube is resting (on the tape) by top when resting (against tread). Hence why I mentioned this is the reason I assumed it was something in the tread. I'm not referring to top & bottom in motion while fixing it. That wouldn't make much sense. Doesn't matter much now I ended up fixing it. Thanks for the tips! Yojimbo_ helped me figure out the general area on the tire.
 

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