Ask a J&P Tech: How to Measure Motorcycle Cable and Brake Lines

Some of the most frequently asked questions we receive [through the J&P Cycles Chat Service] are about extended control lines for oversized handlebars. For example, “I would like to put a set of 20” Wild-1 Psycho Chubby Apes on my bike. What length cables and brake line do I need to order?

If there were a scientific formula to calculate the proper cable and brake line lengths for every possible combination of bars and risers, on every single model of bike, it would make ordering a bit easier. Unfortunately there isn’t, so we always recommend to customers that they mount the bars first, then take an accurate measurement for the proper length cables and brake line.

One method for measuring your cables is through the use of thin gauge wire. Once you have the bars installed and in position:

  1. Route the wire in the same manner that you would like the cables to run.  For example, with throttle cables, start at the carburetor (or throttle body) and route the wire up to the throttle housing on the bars.
  2. Be sure to turn the bars all the way to the left and then back to the right to assure that you will have enough cable to cover your full turning radius.
  3. You are now ready to take your measurement. Use the same method to measure for the clutch cable and your brake line.
  4. Once you have these measurements, subtract the length of your stock cables and brake line to find out how many inches over stock you will need to order (for example, +6 or +8 over stock). Cable and brake lines are measured by the casing length only so do not include the cable itself of the fittings at each end.
  5. Finally, do not overlook the fact that you will need to extend your handlebar control wiring. This method of measuring will work for them as well.

Here at J&P Cycles, we offer handlebar wiring harness extension kits that are available in +4 through +24-inch lengths. These kits are also available for 2008 and later Harley-Davidson touring models with the electronic throttle control.

By |2014-03-28T14:35:56+00:00February 17th, 2010|Categories: Tech Tips|Tags: , , , , , , |14 Comments

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  1. Bruce spencer November 24, 2015 at 8:25 am

    I have a 2011 road King I want to change only Lower part line abs to stainless both sides of abs I also want to change lower leg suspension I saw a a price of 269 for legs do they come with deals need part numbers thank u

  2. Bruce spencer November 23, 2015 at 6:10 pm

    I want to purchase for my 2011 road King classic brake lines lower lines is 245-260 an 245-148 right I want to purchase lower fork legs part 231-556i here they don’t come with gaskets what part number do I need I like new new fork slider cover any part number for that Thank u

  3. glen October 13, 2015 at 5:32 pm

    your paul yaffe orignal part #500-0000 bars. do they require cable or wire extension for 2001 road king classic or should they mount right up as that is what ive heard through the grapevine.

    thank you.

  4. William Banks July 25, 2015 at 3:46 pm

    I was told by customer service to ask tech support to go out and measure JPpart no.#3400590. I need the height & width &depth. Thanks.

  5. John April 12, 2015 at 7:06 pm

    My 80 FLH Shovelhead having a strange issue.. Starter working fine.. Bike intermittently not starting. Seems to start better when cold.. I can start up go for a ride.. Stop for a an hour or even just gas sometimes and it won’t fire… It cranks strong, just not starting.. Is this a solenoid issue or what?

    • Dave Kubert April 24, 2015 at 11:12 am

      My buddy had the the same problem many years ago. It took almost a year to figure it out. We pulled the fuel line off the carb & no gas would go through the filter. Then, sometimes gas would pass through the filter. So, we replaced the filter. That didn’t work, sometimes bike would start & sometimes it wouldn’t. We replaced the vented gas caps & same thing happened. Everything would be fine for a few months then bike wouldn’t start. Finally we replaced the front tank to tank gas line and routed it correctly. Well, that fixed everything. Shovels are temperamental but I wish I still had mine. Good Luck!!

  6. michael November 7, 2014 at 6:17 pm

    I have another question guys. I have a1982 HD roadster 1000. It has two throttle cables. The closed cable has been removed for some unknown reason. The website lists cables as THROTTLE and IDLE. I presume the CLOSE cable is the idle cable.

    Please advise.



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  12. […] our previous blog posts about extending your motorcycle cables and brake lines, and another about measuring for comfortable bars, we thought it’s about time to take on the […]

  13. g. thomas February 18, 2010 at 8:47 am

    very helpful article. many thanks

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