Cema 11-Speed Full Ceramic Pulley Wheels (OS 12-14T)

Cema Full Ceramic Pulley Wheels are oversized replacement derailleur pulleys designed for compatible Shimano road and gravel drivetrains. They provide an alternative to conventional pulley wheels for cyclists who want to upgrade their existing rear derailleur without replacing the entire derailleur assembly. Unlike hybrid ceramic bearings that combine ceramic balls with metal races, the full ceramic construction uses ceramic for both the rolling elements and bearing races. This makes them particularly relevant to riders who prioritise corrosion resistance and bearing durability in demanding riding conditions.

Bearing construction: Cema uses zirconium oxide ceramic for the bearing races and rolling elements. This material is resistant to corrosion, moisture and various chemical influences. Its hardness and wear resistance make it suitable for applications where the bearing is exposed to demanding operating conditions. For cyclists riding through wet weather or frequently cleaning their drivetrains, these material characteristics can be useful. However, the actual efficiency and service life of the pulley system also depend on installation, chain condition and maintenance.

Compatibility considerations: These pulley wheels are intended for Shimano road derailleurs with medium or long cages and compatible Shimano GRX gravel derailleurs. They should not be treated as universal replacements for every Shimano rear derailleur. Before installation, confirm the derailleur model, cage configuration and available clearance. Incorrect pulley selection can affect chain routing, shifting and drivetrain operation. The existing derailleur cage and mounting hardware must also be checked for suitability before fitting.