OPTIMAL USE OF THE ENTIRE BEARING CAPACITY

The load supported by the bearings of a bottom bracket is transmitted from the inner ring through the balls to the outer ring. The greater the number of balls supporting the load, the lower the contact pressure between the balls and the raceway. There is also a direct relationship between the load to which a bearing is exposed and the number of balls that support that load.

Figure shows a schematic diagram of how the load affects different bearings:

Fig. A: Radial ball bearing with large radial clearance. Here a few balls are supporting the load creating a relatively small load zone, easily producing friction and sliding. It is the most common configuration for the bottom bracket shafts.

Fig. B: Angular contact ball bearing with controlled clearance.

Thanks to the preload, the force is distributed among all the balls using the entire raceway to distribute the load, generating a much lower contact pressure. This load distribution reduces the torque required to roll and the greater the demand (sprints, mountain, ..) the greater the difference.