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Installing gears on my bike on my own for the first time.

I pulled the front derailleur gear cable through an intended hole in the frame like so: enter image description here

So everything should be fine. However, looking under the frame, the cable rubs on the frame. Right after it comes out of the guide:

enter image description here

Is this normal? Will it destroy the frame? I would love your take on this.

Yes it needs a wash...

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    it should probably be inside a sleeve for that section, that you can get quite easily. A better guide with a longer tongue would be the preferred choice though.
    – Noise
    Feb 13, 2022 at 16:05
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    Did you get the sides right? I mean - should the wires swap channels in the under-BB bracket ?
    – Criggie
    Feb 13, 2022 at 18:09
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    Or maybe the plastic guide is installed the wrong way around? Can you come up with any combination where neither cable rubs anywhere?
    – Michael
    Feb 13, 2022 at 18:32
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    Definitely do not use it as is, because the cable is going to cut straight through the weld.
    – MaplePanda
    Feb 13, 2022 at 22:58
  • I tried another combination. I simply had to move the slot of the guide.. Thanks guys!
    – nammerkage
    Feb 14, 2022 at 19:28

1 Answer 1

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No, you can't let bare cable rub over an aluminum or carbon frame. In the history of steel frames there have been many frame parts and designs made that do allow rub (see many 70s and earlier lugged BB shells for example), but that's a tangent.

The picture makes it appear possible that if you move the BB cable guide into its other mounting hole, the problem might go away. If not, the cable guide isn't really right for the frame, or something else is missing.

Unless your frame has a proprietary guide made for it that you also can get your hands on, you should replace it with one of the generic ones that support the cable as it runs up between the stays. Here for example is a picture of a set of 3 available on Amazon; the one you would use is the far left.

enter image description here

It's common for bikes with the type of routing showing in the first picture (an upwards-pointing exit for the cable) to have proprietary routing pieces or cable guides that fit up inside. It looks like something might have been lost here at some point.

Cable liner (which can be bought on its own or taken from a shift housing) can be used to mitigate rub in some circumstances. In the right application using it is appropriate or even by design. Here it looks like the cable is wanting to rub over an irregular surface, which is a clue that something else is wrong and liner isn't really a solution.

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  • Did frames really use to have bare cables rubbing on them? Very interesting. With dirt in the system, either the cable or the frame is going to be worn down…
    – MaplePanda
    Feb 14, 2022 at 7:15
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    @MaplePanda Yes, there are many examples, here's a random one: forums.roadbikereview.com/attachments/components-wrenching/… . On many such bikes you could add a piece of liner if you want to reduce friction, but they were intended to be naked. Feb 14, 2022 at 17:42
  • @NathanKnutson you were right, I had to move the screw into the second slot and move the whole guide. Now it fits like a charm! Thank you for the help!!
    – nammerkage
    Feb 14, 2022 at 19:26
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    I have one older steel frame where this happens. To avoid the rub I've pulled some 10cm of liner out of a brake cable and slipped it over the derailleur cable. Problem solved and the cable runs much smoother.
    – Carel
    Feb 16, 2022 at 19:58

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