light-research.md

This is a solved problem in the bike industry — every major component maker now offers an internal cable routing (ICR) system through the headset. Since you're designing the Omera frame from scratch, you can pick the approach that works best.

How It Works

All systems share the same core idea: a slotted compression ring sits inside the head tube between the steerer tube and the upper bearing. Cables/hoses pass through the gap between the steerer and the head tube wall, bypassing the bearing entirely. enduro-mtb

The Three Approaches

Oversized upper bearing (industry standard)

Use a 1½" (52mm) upper headset cup with a standard 1⅛" steerer. The ~12mm gap between the steerer and the cup gives plenty of room for brake hoses, the H1E light wire, and antenna coax to pass through. This is what most modern road and gravel frames use. Your head tube just needs a 44mm bore at the top. forum.customframeforum

Semi-integrated (simplest for a custom build)

Use a standard 1⅛" headset with a slotted top cover from brands like Prestine or FIRST Components. The cables exit from under the stem, pass through slots in the top cover/spacers, and drop into the head tube. No proprietary stem needed — you use any stem you want. [prestine.com](https://www.prestine.com.tw/internal-cable-routing)

Fully integrated (cleanest look, most restrictive)

One-piece bar/stem combos (ENVE In-Route, FSA ACR, Deda DCR) where cables disappear entirely inside the bar and exit directly into the headset. Looks incredible but locks you into a specific ecosystem and makes maintenance painful. firstcomponents

What Makes Sense for Omera

The oversized upper bearing approach is the move:

Head tube design: Weld it to accept a 44mm upper cup (IS52 or ZS56 standard) and a standard lower. Prestine and others sell these off the shelf. prestine.com
Cable path: Brake hoses + H1E wire + antenna coax exit the handlebar, wrap under the stem, pass through the slotted top cover, and drop into the gap between the steerer and the 52mm cup.
Inside the head tube: Everything continues down and exits through a 22–35mm access hole at the HT/DT junction into the down tube. [forum.customframeforum](https://forum.customframeforum.com/t/internal-hidden-cable-stems-headsets-and-forks-resource/2473)
Brake hoses split off to the fork (front) and chainstay (rear) at the head tube junction, while the electrical wires continue into the DT.

The Full Routing Bundle

Everything going through the headset in one pass:

Wire/Hose	From	To
Front brake hose	Handlebar lever	Fork / front caliper
Rear brake hose	Handlebar lever	Down tube → chainstay → rear caliper
H1E light DC wire	Handlebar	DT electronics (KT light output)
Antenna coax (U.FL)	Plastic top cap	DT electronics (BT/GPS module)

Plastic Top Cap + Antenna

This still works perfectly with the oversized bearing approach. The top cap sits above everything. Replace the standard aluminum top cap with your 3D-printed plastic cap containing the GPS/BT antenna. The slotted compression ring and cable routing happen below it, inside the headset — they don't interact with the top cap at all. prestine.com

So your top cap stack becomes:

[Plastic antenna cap]  ← GPS/BT radome, coax exits downward
[Stem]                 ← clamps steerer
[Slotted spacer(s)]    ← brake hoses + wires pass through slots
[Slotted compression ring] ← sits in the 52mm upper cup
[Upper bearing]        ← standard sealed cartridge

The key frame design detail: make the HT/DT junction hole at least 22mm diameter so all four lines (2 brake hoses + light wire + coax) can pass through without kinking. forum.customframeforum

eonist/light-research.md

Select an option

No results found

Select an option

No results found

eonist commented Mar 15, 2026

Uh oh!