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Extra Cable Length

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sansabar
  
How much extra cable is too much? After finalizing all of my swapping to get a fit I am happy with my cabling at the bar has huge loops. It's obvious that I need to take it down some but is there guideline for how much "extra" to leave?

daveornee
  
How much extra cable is too much? After finalizing all of my swapping to get a fit I am happy with my cabling at the bar has huge loops. It's obvious that I need to take it down some but is there guideline for how much "extra" to leave?
" Brake and gear housing allows the cable wire to be routed around bends and connects the levers to the frame stops. The less the drag on the cables, the better for the shifting and braking. Too short of housing will cause it to kink and bind, making even more friction. 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 in a straight approach. For the rear derailleur housing, note especially how the housing enters the barrel adjuster."
Quoted from Park Tool site:

http://parktool.com/repair/readhowto.asp?id=116

kdelong
  
How much extra cable is too much? After finalizing all of my swapping to get a fit I am happy with my cabling at the bar has huge loops. It's obvious that I need to take it down some but is there guideline for how much "extra" to leave? A good way to figure the extra length is to go to your LBS and look at the bikes that they have. Maybe even take a camera and take a picture of a bike similar to yours. When you get home, try to make your cables similar to theirs. Most bike shop owners don't object to someone taking photos of a bike, especially if you tell them that you are shopping for one. This works for me as I am always looking for a good bike at a good price, so I am never lying.

pistole
  
SHIFT HOUSING LENGTH



Typical Tools and Supplies


Cable Cutter:CN-10 (http://parktool.com/products/detail.asp?cat=14&item=CN-10)
Brake housing and cables as needed
Shift housing (compressionless) and cables as needed
Housing end caps (ferrules) as needed
Light lubricant
Mill file (for brake housing as needed). Bench grinder or dermel also useable.
Hex wrenches (http://parktool.com/products/category.asp?cat=7) for cable binder bolts
This article will discuss the cutting and sizing of both brake and derailleur housing. See also related articles on brake and shift levers (http://parktool.com/repair/lever.shtml).

The Park Tool CN-10 (http://parktool.com/products/detail.asp?cat=14&item=CN-10) Cable Cutter is designed to cut multi-strand wires such as gear and brake cable, brake housing, and compressionless gear 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 commonly made of a wire wound around a plastic liner. Use ends caps or ferules at the ends of housing when ever possible. There is also available a woven or braided-type of housing that is may be used for both brake housing and shift housing. It is recommended to lubricate inside the housing or the cable is installed.

http://parktool.com/images_inc/repair_help/housingtypes.jpg



http://parktool.com/images_inc/repair_help/cable5.jpg






The jaws of the cable cutter surround and then shear the material. Using plain diagonal cutters can simply flatten and smash cables. As with all cutting tools, it is recommended to wear eye protection.

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

http://parktool.com/images_inc/repair_help/CN4_cutting_cable.jpg



http://parktool.com/images_inc/repair_help/CN4_cutting_housing.jpg






After cutting the compressionless gear housing, inspect the end to see if it flattened a bit. Use the crimper section of the CN-10 to open up the housing and inner liner before installing an end cap and cable. You can also use the crimper section cutter to crimp on a cable end cap, as seen below.

http://parktool.com/images_inc/repair_help/CN4_crimping.jpg






How Long Should Housing Be?

Brake and gear housing allows the cable wire to be routed around bends and connects the levers to the frame stops. The less the drag on the cables, the better for the shifting and braking. Too short of housing will cause it to kink and bind, making even more friction. 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 in a straight approach. For the rear derailleur housing, note especially how the housing enters the barrel adjuster.



http://parktool.com/images_inc/repair_help/r_der_housing.jpg



In the left image above, the housing bends immediately upon leaving the barrel adjuster. This can actually bend the housing end cap. The image to the right shows how longer housing in this case allows the housing to enter straight.

http://parktool.com/images_inc/repair_help/r_housingloops.jpg



The left image above is a typical new bike housing length. The housing bends and kinks as it enters the barrel adjuster. The image to the right shows longer housing allowing a straight entry into the barrel adjuster.

http://parktool.com/images_inc/repair_help/long_housing.jpg



The image 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.

The routing of housing may affect the length. Typically the front derailleur shift housing is run on the left side of the frame, while the rear derailleur shift housing is run on the right. This may at time cause unnecessary bending in the housing. In some cases, it is possible to "cross over" the housing, running the front shifter to the right side stop, and the rear shifter to the left side stop. It will then be necessary to again cross the cable. Consider this option, but if the cable ends up rubbing the frame, it is not a good idea. There may be some light rubbing between cables, but this would result in less friction than poorly routed housing.

http://parktool.com/images_inc/repair_help/roadhousing.jpg



Shift lever housing that is too long. Housing passes center line of bike, then must bend back to housing stops.



http://parktool.com/images_inc/repair_help/crosshousing.jpg



Shift housing is crossed over at headtube, and crossed again on downtube. Arc of housing is much smoother than black housing in example of too long housing.






Cutting Brake Housing

Brake housing is typically made of single strand flat wire wrapped around an inner plastic tube. This housing may be cut with the CN-10, or diagonal cutting pliers. Because of the design of the housing wire, it is not always possible to get a flat, clean cut. It is best to finish any burr with a file. Lightly grinding the end will also improve the housing and reduce friction.NOTE: Compressionless housing does not require finishing.

sansabar
  
Thanks for the input. I should have thought to look to Park Tools - I have enough of their stuff! All of my cables are fine except the length of the housing at the handlebar. Looks like I will be doing some pulling and cutting.

Retro Grouch
  
Thanks for the input. I should have thought to look to Park Tools - I have enough of their stuff! All of my cables are fine except the length of the housing at the handlebar. Looks like I will be doing some pulling and cutting.
Make sure that you can turn the handlebar completely from side to side. A little too long is better than a little too short. I've worked on some bikes (usually after somebody had raised the bars or done something similar) that would auto shift or apply the rear brake when the handlebar was turned.

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