A generic bicycle bearing system is illustrated opposite. The ball bearings at each end of the shaft run in a "cup/cone" race, one component of which is adjustable to remove unwanted lateral movement in the shaft. Over-tightening of these cups and cones will increase the friction losses in the bearings and remove energy from propulsion. To minimize ball and race wear, the bearings are lubricated with oil, grease, or a solid lubricant such as graphite. These lubricants also reduce the friction losses in the bearing (this is why wear is reduced) and further reduce the energy removed from propulsion. The small inserts in the diagram illustrate the use of this design in pedals (1 adjusting cone), wheel hubs (2 adjusting cones), the bottom bracket (1 adjusting cup), and the headset (1 adjusting cup).

From: Apps, "The Bicycle Book,"
Smithmark (1993)