I don't believe cyclists have any other absolute obligations. It makes sense to ride with good "style", to adhere to the traffic laws (if only to avoid the expense of traffic fines). Treat all other road users with courtesy and insist on courtesy in return. Advocate for respect and room for cyclists on the road. All these things matter, and as a cyclist I try to do them; I don't believe they rise to the level of a moral obligation.
That brings us to the cyclist who rode into an elderly couple and knocked them down, The man escaped severe injuries, but the woman suffered serious fractures and succumbed to her injuries earlier this month. The cyclist fled the scene. Don't do this. Don't ride like this. Don't duck your responsibilities like this. Don't do it, not because it hurts the image of cyclists, not because it gives irresponsible pandering politicians an opening to call for restrictions on cyclists, but because it hurts people. It kills people. It kills vulnerable road users just like us, people we have a responsibility not to injure. Don't flee the scene because the law forbids you to do so; don't flee the scene because leaving another human being in the street, in pain, someone you injured is wrong. It's wrong when motorists do it, and using a two-wheeled human powered vehicle doesn't make it right.
Most of us agree with that. I'll go farther. As cyclists, we belong to a community. Nobody rides alone, if only because riding alone in this city is just too hard. We ride together, we fight for our rights together, and when a cyclist goes down we mourn together. If the cyclist who rode into Ray and Shirley Irving died in a crash tomorrow, we would ride to honour his memory and place a white bicycle to mark his passing.
A pastor and teacher I know calls this "the dark side of Ubuntu": belonging to a community makes us responsible for one another. We would all gladly disown this cowardly act, but we can't disown the person who did it. So what responsibility do we as a community, as members of a community, have? I would say at least this: we have an obligation to speak up. We have an obligation to call on the cyclist to turn himself in. We have an obligation to condemn the act of leaving the scene. Motorists don't speak up abut other motorists, but they don't belong to a community. If I die behind the wheel of my car, I expect nothing from other motorists but the cold vampyric stare of the gawker's block. I believe that if I die on a ride, the cycling community will honour my memory, and therefore my fellow cyclists have a right, and an obligation to expect a minimum of decent behaviour from me, and to speak up if I don't behave with a minimum of decency.