Cables are used to control gear shifting on bikes with geared drivetrains. They consist of two parts: an inner cable of braided stainless steel wire and an outer cable housing, and work by transmitting force using a combination of tension on the inner cable and compression to the housing.
Over time and use cables may become stretched, frayed or otherwise damaged requiring their replacement. Read on to find out more about the different types of cables that are available and to help you choose a replacement when required.
As above, gear cables are used to control gear shifting on bikes with geared drivetrains and may require replacement if the inner cables are stretched, snapped or frayed or the outers are kinked or bent in a way that impedes shifting.
Generally the inner cables are thinner than brake cables (1.2mm as opposed to 1.6mm) but may also be made of stainless steel to combat corrosion with an optional coating to help reduce friction.
Most gear cables consist of a braided steel wire inner and a ‘compressionless’ housing which is designed for indexed gear systems. This consists of linear strands of wire between inner and outer plastic sleeves, which is different to the ‘helical’ construction of brake cable housing (which consists of a spiral of wire wound tightly around a plastic inner sleeve).
Compressionless housing is used in indexed gear systems because it doesn’t change its effective length when bent, allowing for more accurate shifting.
Gear cable kits generally consist of two lengths of 1.2mm inner wire (one longer length for the brake brake and one shorter for the front), and either a single length of cable outer which is then cut to size, or multiple pre-cut lengths.
NOTE: As well as mechanical gear cables, the advent of electronic shifting on road bikes has also meant that replacement electrical cables, batteries and other system accessories are also no available. Wires for electrical shifting systems are generally available in a choice of standard lengths rather than being cut to fit.