I'm planning to build a steel frame myself and want it to be fully internally routed (from the head tube). I'll machine a head tube to fit a system. I think the most popular one is the FSA ACR, but I think the head tube is a bit too big (around 55mm), and my down tube is only 38mm. Another problem is that you'll need 2 spaces under the stem, and everyone would like to go sts on a custom bike. What about specialized or other systems? Which system uses up less space. I would use 12-speed Shimano so only 2 cables are needed.

  • I quite like the Speed Concept routing. It’s horrible to work on but SO clean
    – Noise
    Aug 10, 2022 at 18:24
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    To clarify: “sts” = “Slam That Stem” (putting the stem in its lowest possible position)? Probably best to avoid such jargon in a question posed to such a generalist audience
    – Paul H
    Aug 10, 2022 at 18:53
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    i think there's a question here (basically what are the options for doing a contemporary fully hidden internal routing on a custom steel bike), but you've left it so open-ended that the answer would have to get very expansive about the pertinent design issues of the bike. what kind of fork and head tube are you using? if you want to create the look and functionality of internally routed around road bikes, which is almost all strictly cosmetic in intention, are you willing to accept the weight penalty of using a chunky steel head tube? do you have the tooling to miter non-round tubes? Aug 10, 2022 at 19:16
  • Bordering on a shopping/product recommendation. Please provide answers that avoid recommendations and focus on technicalities.
    – mattnz
    Aug 10, 2022 at 22:34
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    And have you also looked at the Deda integrated system, that is quite easy to get parts for and looks relatively straightforward to integrate
    – Noise
    Aug 11, 2022 at 6:20

1 Answer 1


In the interests of simplicity, I would suggest that you design your frame with access ports in some of these locations:

  • Top of downtube
  • Rear of chainstay - both sides, for rear derailleur and rear disk caliper
  • Bottom bracket area, maybe several
  • Seat tube, one for a front derailleur and potentially for a dropper post
  • Top tube, allow for a rear rim brake cable.

Allow for extra reinforcement here so the frame tubes don't have a weakness despite the holes.

Then design and 3D print some plugs that suit your current needs. Maybe you blank off the rear disk caliper brake access because you have a rim brake currently.

I would simply run full-length housing from shifter downward, passing it through the covers and inside the frame. Some frames have permanently-secured internal guidance and some leave the internal wires flopping in the breeze.

Consider the future too - try and allow for future stuff like DI2 wiring and batteries, disk brake caliper mounts, some lugs for mudguards/racks and top-tube lugs for frame bag and food bag. You can always print new plugs if you choose to add another cable through a hole (like adding an airhorn/permanent light wires, or changing from cable-disks to hydraulic disks.)

Not everything is possible but going to this effort+expense requires careful thought. Good luck!

  • 2
    In terms of aesthetics, there's little difference between half internal routing and non internal cable routing. I would like fully integrated ones using weird shaped headset spacers. But the thing is that it's hard to DIY a stem and almost impossible to make custom bearings. so I'll need to stick with a present system.
    – Zyleyus
    Aug 11, 2022 at 4:35

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