Lemond1985

I got a whole batch of tubes like this. There is apparently a seam on the underside of the inner tube. The seam on this tube appears defective, and was not joined together securely, and keeps splitting open randomly, twice so far, not gonna risk a third.

The reason I'm posting this because of the insistence of some posters here, that they have have worked on bikes, some professionally for many decades, and say they have never seen a defective inner tube. Well, here is one:










And yes, I have thoroughly cleaned out the inside of my rim and checked and re-checked the rim strip, this is an instance of a defective inner tube, I don't see any other way to explain it.

Andrew R Stewart 

Sure... In the shops I have worked at most would have replaced the tube at no tube cost. But after the customer left we would say stuff that wasn't for public viewing. The wholesale cost of a tube is far less then having a customer pan your shop on line. Most all these tubes (the handful a year) don't see the manufacture or supply house, we toss them along with our pride. Andy (who has seen enough manufacturing defects too)

79pmooney

I had poor experiences with Kenda tubes years ago and simply stayed away from them. My advice? Do the same.

rogerm3d

I've been noticing this a lot on tubes I've bought this year, continental tubes (the cheap ones) have all had problems, and some other generic brands also

canklecat

I don't doubt there are some defective tubes. I just can't definitively say I've experienced a failure due to a defective tube. So far every puncture I've had, including on the rim-facing side, has been operator error. I've neglected to de-burr valve and spoke holes, or some sharp debris was embedded in the cloth rim tape, etc.

After patching a slit puncture on the rim-facing side of a tube the other day and letting it sit awhile, I test inflated the tube before putting it away for future use. The tube inflated every unevenly, like an aneurysm in a blood vessel, near the cut that I'd just patched. I don't recall finding anything embedded in the rim tape or tire that might have caused the cut, so ... maybe I did encounter a defective tube. But I usually test inflate every new tube before re-rolling it for the seat bag, and have never found a puncture right out of the box, although I don't mount and fully inflate every new tube.

I can't find a brand name or any ID on that tube. Usually I buy Continental Race 28 and Race 28 Light online, or Bontrager from the Trek LBS nearby, and those are always clearly labeled. I did buy a couple of tubes off Amazon in Panaracer boxes, and IIRC correctly those didn't have any markings on the tubes. But I've also bought some tubes that supposedly were Conti but arrived in bulk pack plastic bags. They might be legit -- I've bought genuine Schwalbe One V-Guards packed that way, no problems.

I've seen a video of a tube manufacturing factory somewhere in Indonesia and was surprised by how crude the factory appeared to be. No idea which names their products are sold under. I'm sure tubes can be made with relatively low tech facilities, but that video didn't inspire much confidence.

hounslow

But that's not the seam, the seam is clearly visible next to it. Defective tubes happen, anything made in the quantities tubes are would have a failure rate.

Eggman84

I don't want to blame Kenda (suspect they don't make the tubes, just market them with their name) but I had at least 5 of their tubes, bought in 2 different batches, appear to be defective. I base this diagnosis on finding small tears (about 1 mm long) at random places , not on seams, and randomly around the circumference. Each tear was essentially identical, and clearly not caused by something puncturing it (checked inside and outside the tire at the location of the tear and found no evidence of anything passing through the tire casing). The latest was on a tour in Washington State this fall where 2 tubes had this happening (had 5 flats over about a 50 mile span). After changing to a different manufacturer (thanks to Bicycle Garage in Port Angeles having tubes and being open) I had no further flats, even after I retraced about 20 miles of the stretch where flats had occurred.

roka

Over the years I’ve definitely had a few defective tubes and tires. Having spent time in the manufacturing world I think it’s safe to say that anything that’s mass produced in large numbers will eventually have some defects slip through no matter how good the quality control measures are.

dsaul

Plastic rim strips cause that sort of damage to tubes all the time. They move to the side and pinch the tube between the strip and the spoke holes or the edge of the strip just abrades tube until it splits. I throw them in the trash and replace with rim tape.

TiHabanero

I have seen this at the shop hundreds of times, even on tubes that have been in use for a year or more. They always split longitudinally. Not sure what causes this outside of the spoke hole opening being exposed or the tube binding on the rim strip in that area and when it expands it tears because it cannot move with inflation. Not so sure it is a defect of the tube or other factor causing the issue. Had a guy many summers ago that went through tube after tube after tube, finally he came in and told his story of a flat every week or month all summer long and they were all the same split like the OP shows. The only thing I was able to come up with was talcum powder. "Well son of a b******" that fixed the problem!

Lemond1985

Wow, that's an interesting theory about the tube shifting as it is inflated. I come here for stuff like that. With this tube, I did hear a couple of "pops" from the tube shifting position once i reached 70-80 PSI. And the longitudinal tear had sort of an indentation in the shape of a "covered spoke hole", even though the rim strip is intact and covering everything properly as far as i could tell. And to have the tube suddenly go flat at some random time I'm not riding also seems strange.

I'm just pissed because I am running 38 mm tires, and instead of using a 700x25 tube like I have done in the past, I splurged and got a properly-sized 700x 35-40 inner tube for once. And this is the thanks I get!

I guess I will run the under-sized tube for a while and see what happens. Hopefully not a sudden "BAM!"

Sy Reene

Quality tube IMO is Michelin, down to the much heartier valve stems out of brass. Not that others can't be fine, but happy with the solid consistency in the quality of product

veganbikes

A defective tube would fail at the seams that one did not. It does happen but not that often or at least I haven't seen it often. A distorted seam on an inflated tube does not a defect make especially if it hasn't failed there. So long as the tube is properly joined a slight wave doesn't really bother me. It is rubber, it stretches and so if it doesn't fail at the seam, it isn't defective.

Lemond1985

So what do you call an inner tube that explodes for no reason while the bike is leaning against a wall? I would call it a textbook example of "res ipsa loquitur", but maybe I'm being excessively harsh in this assessment.

veganbikes

I would call it an inner tube that explodes while the bike is leaning against a wall. There could have been something in the tire or on the rim, too much pressure or some heat changing the pressure...A defective tube is one that fails at the seam. If this had failed at the seam I would say sure probably defective but something like that usually means something else is at foot and maybe you didn't intentionally do something but lots of things can cause punctures. It always sucks but you cannot really blame a tube manufacturer unless they installed everything and picked out the parts.

There really isn't a good system to prevent all these issues but also give a good ride and not require crazy equipment. Tubeless kind of but when you do get a bad puncture you cannot seal or plug you have to use a tube and filling tubes with sealant or other goos just makes a mess and usually doesn't work well and of course solid tires ride like crap and tubulars still have tubes in them and tubeless tubulars are a little better in not coming off the rim but still have the tubeless issues of bad punctures and you cannot replace them easily.

canklecat

The one time I've had a tube pop in a mounted and inflated tire, just sitting in the room, was because I continued using a tire that fit way too loosely on the rim. The tube sneaked out between the rim and bead and burst. That was an old Specialized Hemisphere tire. Not a bad tire otherwise but the bead was slightly too loose for either set of wheels on my hybrids. Switching to better tires eliminated that problem.

I've had a few tubes hiss and flatten gradually, but the tubes weren't defective per se. It was still mostly operator error. I used those flimsy rubber band rim strips that don't adequately support the tubes. The tubes extruded into the spoke holes, weakened and split. There was always a telltale dimpling corresponding with every spoke hole. Took awhile for the coin to drop. No such problems after switching to cloth rim tape or comparably stiff, supportive plastic tape.

And a couple of times I neglected to carefully check the inside of the tire or rim strip for embedded debris. Usually it was something tiny, like a shard of glass or radial tire wire that I'd overlooked during a cursory inspection.

And another couple of times it was a burr around the valve hole, nicking the base of the valve and slowly leaking. De-burring and burnishing the valve holes and, if necessary, spoke holes, solved that problem.

ramzilla

I swore off cheap Chinese bike tire tubes over fifteen years ago. You definitely get what you pay for with bike tubes. My go - to tubes are made by Michelin, Goodyear and, Continental. I'm also a buyer of heavy "thorn proof" tubes too. But, most of the thorn proof tubes have brand names like Sunlite and, are actually manufactured by Kenda or Cheng Shin. These tubes can be as heavy as the tires are. But, they won't blow out. So, provide a good value for recreational riders. I've tried the big heavy "Slime" brand tires too. But, they're a real mess. The green puncture resistant fluid gets into the inflation valve and makes things difficult. Be good. Have fun.

well biked 

Unfortunately, there was a bad batch of Kenda tubes, in that size, with presta valves, that failed in the same place you are showing in the photo. As far as I know, it was just a bad production run, but we had several fail, and once we saw the pattern that they were all failing pretty much in the same way, in the same place, we pulled the few we had in stock off the shelf. I haven't seen one of these failures in a couple of months, so hopefully it was just a single batch of defective tubes. But there was definitely a defect that showed itself in that same location of the tube.;

When I saw the thread title and opened the thread, saw the photo, I thought, "yep.."

well biked 

Btw, Kenda tubes are usually very good in quality in our experience. But there was definitely a problem with that size with presta valves recently.

Lemond1985

It almost seems like a profit model. Build inner tubes that blow out mysteriously. The customer blames himself, and then has to go buy more inner tubes, probably manufactured at the same factory. Hopefully bicycle inner tubes are not all being made at one huge factory somewhere. Because if they are, we had better get used to this kind of thing.

well biked 

Absolutely not that at all. I've been selling and using those tubes to repair flats for customer for a dozen years, this is the first time I've seen a clear, repetitive defect in a Kenda tube. The latest batch we received of this size with presta valves seems fine.

easyupbug 

You are, especially if you mean an event that occurred that would not normally happen unless there was some form of negligence or worse design. As a once design engineer I/we (and others) can design and produce fail proof, like NASA. Problem is history tells us we can't sell any of those perfect tubes at the cost of production, QA and QC, marketing, etc.

Crankycrank

Not much of a profit model. This thread alone has probably cost Kenda a future customer or several. I've used many Kenda tubes and never had a defect. Same can be said for most brands but sometimes some bad ones make their way to the customer.

andrewclaus

It could be called the Ideal Gas Law. This happened to me, after I inflated tires outside before a very cold commute (10F) and then brought the bike inside at work.

mrrabbit 

A tube that's trying to communicate to you your poor tube installation skills?

=8-|