The new inner cables enhance the performance of SHIMANO's new DURA-ACE brake and shifting systems. The secret lies in a new polymer coating that reduces friction. When used with the RD-9000, this cable reduces the effort required for shifting by an impressive 47% compared to the previous cable. Caution with polymer-coated brake cables BC-9000 (polymer-coated brake cables) may only be used in combination with brakes from the BR-9000 series. Using them with other combinations does not provide a secure grip on the brake cable. As a result, the brake cable may loosen, leading to loss of control over the brake, which can cause serious injuries.