A cable guide is a fitting or part of a

bicycle frame A bicycle frame is the main component of a bicycle, onto which wheels and other components are fitted. The modern and most common frame design for an upright bicycle is based on the safety bicycle, and consists of two triangles: a main triangl ...

which guides a piece of bare inner

bowden cable A Bowden cable ( ) is a type of flexible cable used to transmit mechanical force or energy by the movement of an inner cable relative to a hollow outer cable housing. The housing is generally of composite construction, consisting of an inne ...

around a corner. Most multi-speed bicycles have cable guides to get the

derailleur Shimano 600 front derailleur (1980) A derailleur is a variable-ratio bicycle gearing system consisting of a chain, multiple sprockets of different sizes, and a mechanism to move the chain from one sprocket to another. Modern front and rear d ...

cables past the

bottom bracket The bottom bracket on a bicycle connects the crankset (chainset) to the bicycle and allows the crankset to rotate freely. It contains a spindle to which the crankset attaches, and the bearings that allow the spindle and crankset to rotate. The ch ...

. Older derailleur bicycles used either brazed-on or clamp-on guides just above the bottom bracket, but newer bicycles have a guide under the bottom bracket.

Below the bottom bracket

Cable guides below the bottom bracket can be cheaper, just a piece of moulded plastic, and, for some bikes with very small chainrings, eliminate interference between the rear derailleur cable and the bottom of the front derailleur cage. They also make for a cleaner appearance and easier to clean frame in the bottom bracket area. Poor lubrication of bottom-bracket cable guides is a common cause of autoshifting.

Above the bottom bracket

Cable guides above the bottom bracket are usually made of metal, causing more friction and wear on the cable, and is a more complex cable guide as it does not follow the shape of the bottom bracket shell. They do allow use of a slightly shorter cable, tend to keep the cable more clean (as it is more protected from grit thrown up from the road), allow the cable to protect the chainstay from chain slap, and the loop of housing at the rear derailleur does not need to bend quite as tightly, since the cable stop is on the top side of the chainstay, rather than beneath it. Despite the advantages this routing is almost exclusively found on older bikes.

Beside top of seat tube

Some bicycles use a cable guide on one side of the seat cluster for a rear cantilever brake cable, rather than use a short length of housing between two housing stops.

References

{{Bike equipment Bicycle parts