drlogik 

Poor tube quality.

+1--> I completely agree. Twenty years ago tubes were much stretchier and softer. Today, dare I say they have little stretch and feel more like a soft plastic than rubber? The way they are manufactured may be different as well. The mold markings are different now. Notice that mold marker running parallel to the tear? I think the tube failed. If a tube isn't stretchy and soft, it won't give, if it won't give it will break. My guess is that is what happened to your tube.

I've had a few tubes in the last couple of years with similar failures. I'm very particular when I buy tubes now. I will actually pull one out of the box and stretch it before I buy it. I've had good luck with Continentals as well as Vittoria but they do cost more.

rsbob 

Satan, obviously. 👹

Camilo

And put a pump on the bike and carry a little patch kit (with sealed glue tube) on every bike along with the spare tube. OR two tubes.

tshelver

Strange. The only other place I have seen something similar is on a 4x4 I bought years ago with tubed crossply tires. Kept getting punctures even though it was only a year or two old.
Took to a tire shop I trusted eventually, and he pointed out that the patches were all along the tubes' seams. He reckoned the tubes were likely old when fitted to the new vehicle, and already showed signs of perishing.

Replaced the whole set with new tubeless radials, problem solved.

Would also check the rim strip. The ones on my Trek 7300 I bought last year were not in great condition, and had started to damage the tubes, but nothing like what you have.

Tony

rsbob 

Have to say that I have been amazed at the broken glass I have accidentally ridden through on my tubed and tubeless GP 5000s and not flatted. With the Michelins and other tires I used to ride, flats were guaranteed.