Final answer:
To the moving bicyclist, a stationary observer on the sidewalk appears to be moving in the opposite direction of the bicyclist's travel.
Step-by-step explanation:
When observing a bicyclist from the standpoint of being a pedestrian on the sidewalk, the perception of motion is relative to the reference frame being used. If you are facing the road and see a bicyclist passing by to your right, the answer to what direction you are moving in, relative to the bicyclist, would be in the direction opposite to the motion of the bicyclist. This is because, from the bicyclist’s reference frame, since they are moving forward, any object that’s stationary with respect to the ground would appear to be moving backwards. This concept is a fundamental part of understanding relative motion in physics.