Final answer:
In the reference frame of the bicyclist, a stationary observer standing on the sidewalk would appear to be moving toward the left, due to the principle of relative motion.
Step-by-step explanation:
When observing from the perspective of the bicyclist on the road, the concept of relative motion applies. The reference frame of the bicyclist is moving in the opposite direction of the sidewalk observer. Therefore, in the bicyclist's reference frame, it would appear that the observer on the sidewalk is moving toward the left. This occurs because motion is relative; as the bicyclist moves toward the right from the sidewalk observer's perspective, the observer would seem to be moving toward the left for the bicyclist, assuming the observer is standing still.