HOW TO SILENCE A RATTLING INTERNAL CABLE – SILENCE IS GOLDEN

Internal cable routing is advantageous for very few reasons. It makes the bike look cool, and that’s about it. Bike designers will tell you it’s the only way to go, but mechanics will tell you a different story. Some internal cable-routing systems feature internal sleeves that guide the cable through the frame with ease. When you need to replace a cable or housing, there’s no need to fish it through or go hunting with a flashlight and a pick. These systems are expensive to include on bikes and add weight to the inside of the frame tubes. Oftentimes, the internal routing system is nothing more than two holes in the frame, and the routing between the two points is left for you to figure out. In this month’s “Garage Files,” we’ll show you our favorite tricks to guide the cable and housing through the frame should you need to replace it. Then, we’ll show you how to keep it from sounding like a rattling penny in a steel can.

 

The Norco Fluid is one of our favorite bikes tested this year, but the dropper line rattles in the downtube on rough terrain. Jagwire makes this foam tubing specifically to solve this issue by damping vibrations inside the downtube.

 

Start by disconnecting the line and lever. Most dropper levers will use a small pinch bolt that can be loosened to remove the cable.

 

This rubber grommet is designed to keep the hose from moving while you’re riding. It does a little to keep it from rattling at this port, but the housing can still hit the inside of the downtube and make a racket.

 

Cut a piece of the foam tubing that’s about the same length as the downtube. You won’t need to go around the bend and all the way up the seat tube. The rattles happen in the downtube.

 

Cables that have been used and cut to length are particularly prone to fraying like this. You can simply cut the frayed strands for a dropper post, since there’s not a ton of force put on this cable. It will be more difficult to reinstall in the housing without the cable fraying more.

 

Carefully remove the seatpost from the bike. The cable will come with it. Know that if your cable is frayed at the end, you will have a difficult time reinstalling it, so it’s best to have a new cable to install later on.

 

Flashlights are your best friend when working on any internal cable-routing system. Here, we can make sure the cable housing isn’t too out of reach to thread a new cable into the housing.

 

We tried to shoot this “Garage Files” with the existing cable but gave up on the effort. Given that a new cable is only about five bucks, this is the cheapest way to avoid frustration and a likely trip to the bike shop later anyway.

 

You can now remove the old cable from the post base. Some posts use cable knarps with a pinch bolt, but this post only uses a cable-head adapter. Be sure not to lose this tiny bit of critical hardware.

 

Using the flashlight, we were able to thread the cable through the housing down in the seat tube. Housing here rarely needs replacement unless it’s damaged. The cable should slide easily into place.

 

Replace the cable-head adapter and reconnect the dropper post to the cable. Now you’re ready to reinstall the seatpost in the frame.

 

Pull the excess housing through to the correct spot. This is a great time to check your work. Make sure that the cable still feels connected to the post actuator inside. Sometimes, the head will disconnect as you reinstall the post, and your lever won’t feel like it’s pulling anything.

 

Now it’s time for the Jagwire cable insulation. The install is easy here; just slide it on.

 

Different bikes will have different-sized ports here, so how difficult it is to install will vary. The Fluid has average-sized ports, but we still needed a spot of lube to slide the foam tube inside the frame.

 

If you’re having difficulty sliding the foam in one piece, there’s no issue with cutting the foam into smaller pieces. This allowed us to install the foam much faster.

 

It’s not rocket science; just get the foam inside there. A flat-bladed screwdriver may have worked better, but the edge of this scissor blade helped. Be cautious if you’re using a sharp tool on a line that’s hydraulic, as this could cause obvious issues.

 

With the foam inside, the cable already feels fantastically quiet. It’s time to reinstall the cable-port grommet to finish the job.

 

Reconnect the cable to the dropper lever.

 

Always be careful when tightening small pinch bolts like these. Oftentimes, the torque rating is only 1 Newton meter, which makes those tiny threads very easy to strip. A torque wrench is ideal here, but using attention and caution when tightening works, too.

 

Don’t forget to crimp the cable end to keep it from fraying next time.

 

Finally, before you head out to test your new cable setup, be sure the housing is pulled taut so there’s no extra length inside to move around. Spend a few seconds situating the cable and housing so that it makes the least noise here in the stand, and it will be quieter on the trail. While some bikes use a bolt here to keep things in place, the rubber grommet does a reasonable job. Time to go ride and enjoy the serenity.