As always the major overall bicycle requirements are speed, safety, comfort, and endurance.
The bicycle weight is the key to speed, but the lightweight need must be balanced by the other factors (safety, comfort, and endurance).
Wheels are fundamental to the purpose of the bicycle. A bicycle wheel is made up of a hub, spokes, a rim, tire, and tube. Each part of the wheel may require different material properties. Our focus will just consider the materials for the hub, spokes, and rim.