Hi Eric, I cant be sure what gear I was on at the time (I'm sure there are a few pro's out there who've used that phrase before
but I wasn't changing gears, I was in the gear at the time it broke.
You have an excellent point in that a cassette should be able to deal with other minor forces and not break apart.
Simple fact is however, I've broken three DA cassettes.
I've got SRAM cassette on now and it works perfectly, gears change precisely... absolutely nothing wrong and all I did was put it on(myself) and adjust the gears. That's it.
As I said before there are no issues now with the bike now and there wasn't before hand, bought a SRAM cassette and problem solved... but if you simply can not accept that this product is a bad design after you break one... Try you luck with the following tips from 11.4
"I'd honestly suggest that you have the bike hangar and drive train alignment checked by someone who really knows what they're doing (preferably a good frame builder). Go to a different chain and intentionally change the number of links. Change the b-screw setting. And so on. Be sure the free hub isn't sticking at all, nor the rear derailleur jockey wheels -- fastest way to get this kind of failure is if a couple links fold up and jam on the cassette right above the upper jockey wheel -- you'll have a failure essentially without warning even if the cause has been there all along or since a change induced the scenario. My point is that there's a way to tear a cassette spider apart, and it can come about from a combination of issues that is almost impossible to diagnose or predict. The cassette is generally reliable and riders shouldn't be hesitant about using them, but if you do start to have problems with one, I'd look at the whole drivetrain and its geometry to see what is causing this"