You're conflating lots of things.
Addressing your first paragraph:
The point at issue was whether reallocating some roadspace from autos to bikes would be a good thing to do, not whether the climate of the US made it inherently unsuitable to ride a bike at all in (a contention I find pretty risible, to be honest). Nor was it a debate about whether or not cycling was inherently risky due to autos, whether in Manhattan or anywhere else. In fact, and pretty obviously, the whole point of cycle superhighways is to encourage cycling by reducing this risk. And I wasn't claiming that this risk was eliminated in Manhattan, I was simply saying that there are in fact routes in a major US city where auto space has been reallocated to cycles. Nor was I claiming that the amount of space reallocated needed to be large. You don't in fact need that many major bike routes with reallocated space in order to effect significant benefits for many cyclists. TfL studies go into this point in some detail, should you be interested. I am well aware of what CityBikes are, given that Boris bikes are common in London, and work on a very similar model.
Addressing your second:
Closing off streets has not happened yet. It is contentious but it will happen (and has happened in NYC too). The congestion charge is not material for cycle superhighways. The two policies are mildly synergistic, but there is no cause and effect. The tube is also not material for cycle superhighways. On culture: well, sure. But you said it was impossible in your first reply to me, not merely that it was difficult.
I don't think it's impossible, as you have been arguing. I do think that it's difficult, that it requires an effort of political and cultural will that is largely lacking, and that it doesn't work everywhere. But it could still be worth the effort.