Cables are used for braking on bikes with cable-pull brakes. 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.
MTB/Road brake cables are interchangeable and used for bikes with cable-activated brakes (rim brakes and non-hydraulic disc brakes).
• Caliper brakes: As used on the majority of road bikes.
• Cantiliver brakes: These can be either the side-pull ‘v-brakes’ found on many MTB and city bikes or centre-pull cantis found on Cyclo-X bikes.
• Cable-activated disc brakes: Such as the popular Avid BB5 standard as used on many entry- to mid-level MTB bikes as well as on an increasing number of Cyclo-X and road bikes.
While brake and gear inner cables are nominally similar, the housings are different – brake cables use conventional ‘helical’ housing which consists of a tightly-wrapped helix of steel wire lined on both inside and outside by a plastic coating. Gear cable outers use a different, ‘compressionless’ housing which because it doesn’t change its effective length when bent is more suitable for indexed gearing systems where accurate cable pull is essential.
Gear cable housing (compressionless) is not as strong as standard helical housing and should not be use for brake cables as the forces involved could cause it to rupture and burst.
When buying MTB/road brake cables you will have the option of buying either the cable inner only, or a full cable kit with housing. The former may do fine if you are simply replacing a broken cable but in the event of an overall upgrade or the old housing being bent/damaged (which will affect cable performance) you may need a full kit.
Brake cable kits generally consist of two lengths of 1.5mm or 1.6mm inner wire (one longer length for the brake brake and one shorter for the front), a single length of cable outer which is then cut to size and all associated end caps and ferrules etc.
When cutting the cable outer to size be careful to:
• Cut the correct amounts of rear brake cable housing to suit your frame design – most are intended to have lengths of cable exposed between certain points (e.g in straight lines between cable stops on top or down tubes or chain/seat stays).
• Cut the correct lengths of cable housing – too long will result in unnecessary friction, too short will mean the brakes can’t actuate enough.
• Cut the housing cleanly – use a good-quality shears or cable to achieve a clean cut and avoid crushing the end of the housing, which will affect the cable’s performance.
If in doubt, cut the outer cable lengths to match your old ones or refer to online resources or tutorials for a breakdown on how to replace brake cables. As a rule of thumb, try to size the housing so it is as short as possible but it still enters the cable stops in a relatively straight line. Inner cables can be snipped with a wire cutters once the brakes have been adjusted correctly, and an end cap crimped over the cut end to prevent fraying.
Basic brake cables are inexpensive but higher-budget cables and housings will add features such as improved corrosion resistance and friction-reducing coatings on the inner wire and housing. They can be a relatively inexpensive performance upgrade to boost the braking power of your bike.
BMX brake cabling is generally straightforward with most bikes using a rear U-brake only and so most brake cables involving a standard 1.5mm inner wire and full-length outer.
However many BMX riders favour linear brake cable housing rather than the standard helical type. Linear housing consists of linear strands of wire between an inner sleeve of friction-free teflon and an outer sleeve of nylon (as opposed to the regular helical style which consists of a spiral of wire wound tightly around a plastic core). Linear brake housing is similar in construction to the compressionless housing used in indexed gear systems but is stronger to cope with the increased forces involved in braking.
Fans of linear housing say it enables more force to be applied to the brakes, and also has a reinforced outer jacket that is more resistance to abrasion and kinking than standard housing.
Finally if you are running a gyro or detangler to enable you to perform tricks like barspins or tailwhips you will need a specific cable designs – or rather two of them, upper and lower. A lower gyro cable runs between the gyro and the rear brake and an upper gyro cable, with a split cable design to even out the pressure exerted on the top gyro plate, goes between lever and gyro.