Even if the van was doing an illegal maneuver, I think cyclists sometimes think they can just roll through situations like this without slowing down, owing to the thin profile and maneuverability of the cycle. If I see a vehicle and I'm not sure what it's doing, whether I'm in a car or on my bike, I slow down. On my bike, even more so, because even if the car is in the wrong, I'm the one that gets injured/killed if I misjudge the situation. Always give yourself a positive safety factor!
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I stop for people / whose right of way I honor / but not for no one.
Originally Posted by
bragi 
"However, it's never a good idea to overgeneralize."