Got the blackspire stinger copy on my heckler with an SLX double. To get it to work in teh granny ring i have had to bend the back plate - otherwise it rides up on top of the roller edge.
This works fine when pedaling forwards, but back pedal and the chain derails, it also comes off if i change to an easier gear at the back if in the granny ring at teh front (when under pressure)
What have i done wrong or are they just shite?

