Which sensors should be used throughout the robot?

[thatprogrammer]

Originally Posted by Knufire

The silver shaft rotates. You mount the encoder with a nut on the brass-colored threaded portion, which will also hold the black housing stationary.

From what I've seen, most teams just mount these by drilling a quarter inch hole and putting them in. How does the shaft still spin with the axle if the hole is a larger diameter than it is?