How do I cut cables and housing?

Required Tools and Supplies:

• Park CN-4 or CN-10 Cable Cutter.
• Brake housing and cables.
• Shift housing (compressionless) and cables.
• Housing end caps and cable crimps.
• A light cable lubricant like ProGold.
• Flat sided file for finishing your brake housing ends.
• Hex wrenches for cable binder bolts.

PROCEDURE

The Park CN-4 and CN-10 are designed to cut multi-strand wires such as gear and brake cables, brake housing, and compressionless shift housing. Compressionless shift housing uses many inner support wires running longitudinally with the inner plastic liner. Compressionless shift housing is intended for shifting systems only, not braking. Brake housing is made of a flat wire wound around a plastic liner. Use ends caps at the housing ends when ever possible. We recommend lubricating the cable before it is installed.

The jaws of the CN-4 or CN-10 surround and then shear the material. Using plain diagonal cutters can simply flatten and mash cables.
Keep away from other people and always wear safety glasses when using any cable or housing cutter. Cable and housing ends are sharp and often fly a few feet (1 meter) when cut. Cable and housing pieces can easily damage your eyes or someone elses. Left on the floor or in the carpet they are a hazard to small children, bare feet and have even been known to flatten bicycle tires. Please use extra caution when cutting and be sure pick up scrap pieces of cables and housings.

Grab and hold the cable or housing close to the jaws of the cutter. Use care not to cut your fingers. Hold the cable or housing perpendicular to the jaws and squeeze the handles quickly for a clean cut, as pictured below.

 

After cutting the compressionless gear housing, inspect the end to see if it flattened a bit. Use the crimper section of the Park cutter to open up the housing and inner liner before installing an end cap and cable. You can also use the crimper section of the cutter to crimp a cable end cap, as pictured below.

HOW LONG SHOULD HOUSING BE?

Brake and gear housing allows your cables to be routed around bends and into your brake or derailleur. For smoothest operation you want the housing bends to be gradual and properly aligned. A common error is to cut housing too short. Short housing makes for sharper bends, more cable/housing friction and rougher shifting or braking. As a rule of thumb, try to size the housing so it is as short as possible but it still enters the stops and barrel adjusters with a straight approach. Note how the housing enters the rear derailleur barrel adjuster pictured below.

In the left image above, the housing bends immediately upon leaving the barrel adjuster. This often bends the housing end cap, increases friction and reduces shifting performance. The image to the right shows how a longer housing keeps the derailleur cable aligned and reduces friction which improves shifting performance.

The left photo above shows a common mistake. The rear derailleur housing was cut too short. Note how the housing bends and kinks as it enters the derailleur barrel adjuster. The picture to the right shows a proper length housing that allows for a smooth, straight cable entry into the rear derailleur barrel adjuster. The housing looks long but the rear deraiileur on the right shifts much quicker than the one on the left.

The photo above shows brake and shift housing which is much too long. The housing could be shortened and still have a smooth, straight approach to the levers and housing stops.

CUTTING BRAKE HOUSING

Brake housing is typically made of single strand of flat wire that is wrapped around an inner plastic tube. Brake housing is easily cut with the Park cutter. Unlike gear housing, it is not always possible to get a flat, clean cut with brake housing. We use a flat file to remove any burrs.

ADJUSTMENT OF THE CUTTERS

As the CN-4 or CN-10 wears, it will require readjustment for best cutting results. Grab the handles and wiggle them against the axis of the centerbolt. If there is play between the handles, turn the locknut counterclockwise to loosen it. Then turn the centerbolt head clockwise slightly to tighten the adjustment. Then retighten the locknut. Repeat adjustments as needed unitl the tool cuts cables smoothly and cleanly. If the handles bind, turn the locknut counterclockwise to loosen it. Then turn the centerbolt head counterclockwise slightly to tighten the adjustment. Then retighten the locking nut. Repeat adjustments as needed unitl tool cuts cables smoothly and cleanly. Park cable cutter tools will wear out after several years of use or if they are mis-used. If adjusting the centerbolt does not yield better cutting it may be time to purchase a new pair.