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Road Bike Drivetrains and Using Cable Liner to Keep It Clean and Light… And What to Do About Rattles for Internally Routed Cables

Cable liner is used on internally routed mountain, gravel and road bike drivetrains. It’s considerably lighter than cable housing and can keep your cables from being exposed to the elements.  There is a weight trade-off for the weight wienies, but it’s not enough for me to worry about – liner is extremely light.

The most common place to use cable liner is at the bottom bracket cable guide located under the bottom bracket shell (though some will use it the entire length of the exposed cable inside the bike’s frame to help with rattles – I’ll cover that later):


One can imagine how gnarly the cables would become over time if they were left exposed to road grime and rain…

The center cable goes to the front derailleur.  The one on our right goes to the rear derailleur.  

Now, when I picked up my Venge at the bike shop, the front derailleur cable liner only poked out of the frame by an inch or two.  When I changed out the shifter cables after four years (double what is recommended for exterior routed cable systems, but a little quick for interior routing), I decided to go all out.  Go big, as they say.

On the left, the bike is rubber-side down, but it’s a little tough to get a decent photo.  The photo on the right is with the bike rubber-side up and with the tire removed for clarity… so basically, what I’ve got is a 6″ piece of cable liner for the rear derailleur cable, but a piece that runs from the inside of the top tube at the cable guide, all the way up to about an inch below the front derailleur cable bolt.  About 3″ longer than what was originally provided, and enough that it keeps most dirt away from the cable.

Now, the cable liner is not to be confused with the cable housing.  Cable housings are 4 or 5 mm, while the liner is anywhere from 1.6 to 1.9 mm depending on the manufacturer.  On a road bike, your brake cables are going to be around 1.5 mm and your shift cables are 1.1 or 1.2 mm.  Most of the liner you’ll find on the web is the 1.8 or 1.9 mm (1.8 for the black non-coated and 1.9 for the lube-coated – white).  I’m obviously partial to the non-coated and I use the liner for not only protecting the cables on the bike, but as a guide to run the internal cables without fuss.  

20200115_0611508692555482018040516.jpg
The plastic and two metal pieces are ferrules or end caps.

Cable liner can be found online in 30 meter rolls (90 feet) for $10 to $15.  

In a future post, I’m going to try to use cable liner on my Trek 5200.  The cables are externally routed on that bike so I’m going to try to cover up the rest of the cable that usually sits exposed and see what happens….  more on that later.

Now let’s get to the internal routing rattles.  Rattling was a problem in older internally routed bikes but most brands have addressed the issue with housing stop inserts.  The inserts keep the cable from resting on, or hitting, the frame.

Spec.CableStop_2013
Kit for a 2013 Specialized with internal routing (Venge, Tarmac, Roubaix, Ruby, Crux [carbon])

The insert (second from far right) slides into the frame far enough the taught cable can’t bounce and hit the frame.  My Venge uses four of these.  One at the entry point into the down tube of each shifter cable and two for the rear brake housing (where the housing enters and exits the frame).  Specialized’s answer was fantastic.  I’ve never had a problem with cable rattle while friends have other brands and complain regularly about cable slap.  By the way, I bought a pack of four inserts at my local shop to keep in my tool bag… just in case they’re ever discontinued.  This is one of those items that, 20 years down the road, they’ve stopped making and you have to bodge up a workaround… unless you’ve got the parts already.  Incidentally, if you’re wondering, the piece on the far right in the photo above is for rear derailleur cable at the right rear seat stay, where the cable housing loop goes into the frame at the bottom of said seat stay.

What can be done to limit the rattle if your frame doesn’t make use of inserts?

Well, there are a few simple solutions:

  1.  Use cable liner.  This will dampen the noise considerably, but it won’t completely stop the cable slapping the frame.  
  2. Go naked on the cable routing inside the frame and use the donuts they provide with shifting cable replacement kits – your local shop will have thousands of them… you can also buy them online by searching “rubber shift cable donuts”.  Install four to six on a cable, spacing them equidistant from each other and your problems should stop.  The problem here is, you know they’re going to slide down if you’re using them on the shift cables in the down tube...
  3. So go all in and use a combination of items 1 & 2… put the donuts over the cable liner.  It’ll work.  I just tried it to make sure so I could add this to the post.  It takes a little dexterity in the fingers, so don’t attempt this if you’ve got arthritis… it’ll just piss you off.  Call a kid over to help… and you’ll be able to re-use that liner over and over again when it’s time to change your cables.  This will solve the problem of the donuts sliding down the cable, too.
  4. Install a cable liner over the offending cable and, where the cable will be about 12″ into the frame, put a zip tie around the cable/liner.  Don’t cut the end of the zip tie, wrap the end around the cable and insert the whole thing into your frame.  The zip tie end will unravel and hold the cable away from the frame.  

Greg J., this post is for you, bud.  

If it were me, I’d go with option three out of the four.  Option three, from a “continued use” aspect, seems like the best to hold up to how I ride my bikes.  Once I got a donut on the liner, it wasn’t going anywhere

There’s maybe a 10 gram weight penalty for doing it, but that’s a small price to pay for a quiet bike.  And that’s the one thing that trumps bike weight; silence.

Ride hard, my friends.