We're stumped by those weight-activated turn arrows at intersections. When you're on a bike, what do you do? If you're at the head of the line, you don't have a car in front to trigger it and you're there forever. (And sometimes drivers politely avoid crowding you, and don't trigger the plate behind you.) We're baffled. Sometimes we bike through the crosswalk instead. Sometimes we just turn a street early to avoid the light. Is......