Final answer:
In the reference frame of the bicyclist passing by to your right, you are moving to their left because of relative motion, as you're stationary with respect to the Earth.
Step-by-step explanation:
When considering the situation where you are standing on a sidewalk and observe a bicyclist passing by toward your right, it is crucial to apply the concept of relative motion from physics.
In the reference frame of the bicyclist, the direction of your movement depends on the relative motion between yourself and the bicyclist. Since you are stationary with respect to the Earth and the bicyclist is moving to your right, from the bicyclist's reference frame, you would appear to be moving to their left.