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I'm working on adding a front derailleur to a folding bike that started as a 1x setup.

Today I got a front derailleur mounted, and realised that I need some form of cable stop for the inner cable. There is nothing on the frame already.

Given my FD is a bottom-pull, I will also need to bring the inner cable up from below, which means wrapping it under the Bottom Bracket housing.

Can I use a brake noodle to deal with the turn under the BB? If not, why not?

I have to use a full-length of housing from the shifter downward. If that terminates at the noodle, which will both turn the inner cable upward, and leave the inner cable aiming at the FD clamp. In theory I can get away with cable ties to secure the housing for most of its length.

Either e flexible cable like this: enter image description here

Or a traditional hard noodle like this: enter image description here

Gear cable is thinner than brake cable, so will fit through perfectly well.

The only downside I can see is aesthetics or tradition, if you prefer, which does not matter at all.

  • Is there a reason why you can't use a standard cable guide? – ojs Jan 19 at 14:19
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    It’s not uncommon for noodles to be used for shift cables on the type of road brifters where the shift cable comes out of the side of the brake lever hood. The noodle turns the cable path in order to reduce interference with a handlebar bag. So it should work for your application as well – Andrew Jan 19 at 14:27
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    @ojs I require a cable stop to terminate the outer housing, and it has to come from below. A regular under-bb guide will interfere with the folder's seattube which is behind the BB. And I'd still need a cable stop, but there's no traditional downtube on which to put it, so the inner would end up doing a 180 degree turn around the BB – Criggie Jan 20 at 12:39
  • UPDATE - I've ordered a bunch of different noodles, Flexible, 90 degrees and 135 degree bends, and a couple of generic under-bb plastic guides. Will update with which works better in a month or so. – Criggie Jan 22 at 5:47
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The flexible versions might be too “soft” and change slightly in length when the cable is tensioned during shifting. They also have a tendency to straighten under load. Shifting cables and housings have to stretch/compress as little as possible for best shifting experience.

This is also critical for your DIY installation: If the “effective length” of your cable housing can change (e.g. because you are using zip ties as cable stops which have some give) it’s going to ruin your shifting performance. That being said, for a 2 speed front derailleur you might be able to get away with your plan for using a continuous shifting cable housing all the way to the bottom bracket and a rigid brake noodle at the end.

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