So today my ZTTO cassette decided to self destruct...
All of a sudden, while crossing a busy road, my crank was spinning but the rear wheel was not. Seems the smallest 3 cogs had separated themselves from the rest of the cassette. All the pins had failed. Luckily the rest of the cassette was more or less in one piece and I could finish my ride without using the 3 smallest cogs.
Shifting was horrible though and the chain skipped on some cogs. I had no idea why until I took the cassette off the rear wheel when I got home. Not only the smallest 3 cogs came loose, but also in a few other places the cassette had come apart.
I bought 3 of these cassettes and not one worked very good or long. But this one was the worst. I don't know the mileage exactly, but I guess this cassette maybe had 3000 km.
I now replaced it with a SRAM GX 10-42 cassette. Needless to say I expect a much longer life from this cassette.