canklecat

I suspect it's mostly operator error.

I'm sure defective tubes occasionally appear but I've never seen one. Every time I thought a tube was defective it turned out to be operator error or neglecting to burnish burrs around valve holes (the usual cause for nicks and leaks around the base of the valve), or using inadequate rim strips that don't support the tubes (lots of dimples around the tube where it tried to extrude into the spoke holes -- cloth tape or really stiff plastic tape work better than those cheap rubber bands that come with most bargain wheelsets).

The closest I've seen to a "defective" tube was when a really old Presta tube with brass valve and core finally corroded so much it broke. That tube was probably 30 years old, and came with the bike when I bought it a few years ago.

I've read those Amazon reviews and most of the negative reviews claiming the tubes were defective sound like rookie errors. But they'd rather blame the tube than admit to pinching it while using a tire lever to mount the tire.

Same thing I discovered teaching basic b&w darkroom: Very few people are willing to admit to mistakes. The dumber the mistake, the more likely they are to deny it. One of the most common complaints I heard from newbies to the darkroom was "My film came out completely blank. Nothing, not even fog, no margins between frames, nothing." That's usually due to fixing the film before developing. In fact, I'd say it's 99.99% due to that very operator error. People prepare the developer, stop bath and fixer in containers, side by side, and grab the wrong container in the dark. But I've never heard a single student admit to having done that. But when they change their habits -- for example, there's no need to pour fixer into an open container and set it next to the developer -- miraculously their negatives turn out as expected.

Advise people to use a bead jack on tires that are difficult to mount (Kool Stop makes and excellent and inexpensive one), and most "defective" tube problems seem to vanish.

I use the same method for butyl tubes that Silca demonstrates in an excellent video for mounting their latex tubes. It's good methodology. I also use Continental's ultra-thin butyl Race 28 Light tubes, which are also vulnerable to user-induced punctures from carelessly pinching the tube between the tire bead and rim while mounting.

Basically:

• Pre-inflate the tube just enough so it'll hold shape. Doesn't take much air.
• Use corn starch or similar safe powder to keep things from sticking (Silca now pre-powders their latex tubes).
• Use your hands as much as possible to seat the tubes and tires, feeling carefully for the tube trying to sneak out and get pinched.
• Use a bead jack if necessary, but never a tire lever unless it's unavoidable.
• Inflate the tire to only around 20 psi, then rotate the wheel and inspect the bead on both sides to be sure the tube isn't trying to sneak out. Inflate to 40 psi and check again. Same at 60 psi. With skinny road bike tires that's usually the point where slightly crooked beads will begin to seat themselves straight. I'll usually pump to 100+ psi, then deflate to my preferred riding pressure (I usually ride 60-75 psi front).