Internal / Hidden Cable Stems, Headsets and Forks Resource

Education Resources
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Hi Friends,

One of my last projects at ENVE was helping to develop the In-Route (hidden cable) System. During the development process I compiled a list of all products that support full internal cable routing and have continued to add to it. After consulting with many builders about the subject I wanted to share it here.

HIDDEN CABLE SYSTEMS - Here’s the complete list of every internal routing product available to builders. This includes proprietary headset/stem compatibility. Please comment here or in the sheet if I missed any!

ROUTING
There are two methods of routing for aftermarket products.

  1. Oversized Upper Bearing - Utilizing a standard 1 1/2" (52x40) upper bearing allows the cables to pass between the bearing and a standard 1 1/8" Steerer tube with adequate clearance. This is far and away the dominant standard and has been adopted by most large brands as well. The Downside? There is no standardization of the stem/headset interface so stems and headsets need to be purchased within the same design ecosystem.
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  2. D Shaped / Custom Shaped Steerer Tubes - These designs remove material from the steerer tube in order to make room for the cables. This allows for full internal routing while maintaining the compatibility with almost ANY standard 1 1/8" headset and stem. What’s the Catch? This design has less surface area for for both the stem and upper bearing race making it incredibly difficult to design a fork that maintains the strength and safety of a proven 1 1/8" steerer tube. Additionally these designs are limited to electronic drivetrains only. Columbus new Trefoil fork (pictures below) looks really promising and they have done extensive testing to ensure safety.
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    Note: Both these systems require forks specifically designed for internal routing and will feature a hole in the steerer above the crown race for front brake routing.

HEADSET/STEM INTERFACE

  • As mentioned above, the oversized upper bearing design lacks standardization of the headset/stem interface. This requires the stem and headset be purchased within the same design ecosystem. Pictured below are the ENVE In-Route, Deda DCR and FSA ACR Interfaces. Reference the Hidden Cable Systems doc for a complete list of compatible headset and stems.
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HEADSET STANDARDS

  1. EC44/EC44
    I want to make sure everyone is aware the ENVE EC44/EC44 Cups Only (without bearings) can be purchased separately and be paired with any IS52/IS52 headset from Deda, FSA, Token etc. to make a complete EC44/EC44 system. When creating skus for the headset I made sure the cups were sold separately for this very reason. (See below for an example of the ENVE EC44 Cups paired with a Deda IS52/IS52 headset and stem) White Industries has also made some prototype cups for use with IS52/IS52 headsets.
    imageimage

  2. IS52/IS52 Spec - 8.7mm Upper bearing Drop
    If you’re looking to make a custom Headtube then it’s important to note the unique 8.7mm upper bearing drop used for all these full internal headsets. FSA led the charge with this spec and luckily all full internal headsets have followed suit.
    Screen Shot 2023-11-10 at 3.47.46 PM

RETROFIT POSSIBLE?
In some cases older frames can be converted from semi internal to full internal with the products listed above. Rob English did an amazing job converting a semi internal frame he build in 2016 to full internal.

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If you’re interested in converting or building a full internal frame it will need to meet the requirements below

  1. Headtube must be designed for a 44mm upper headset
  2. Cables must route internally into the downtube
  3. Headtube/Downtube access hole must be a minimum of 22mm
  4. Access hole above is maximum 35mm from headset cup
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I wanted to create this as a resource but there has been some great discussion on The Great Internal Cable Routing Debate Topic already. If you have opinions on full internal routing that’s a great place to keep the conversation going.

Feel free to hit me with questions!

//Kevin

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Thanks for posting! After struggling to find some of this info, it’s really nice to have it in one place.

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Fantastic!! Thank you!

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Wolftooth has entered the chat with a EC44/EC44 Headset!

It’s designed around the ENVE Stem Interface and it looks like they prioritized the EC44 design to make it as low stack as possible. Other options like the ENVE and FSA Headset use a taller stack so the cover is compatible with both IS52 (8.7mm) and EC34.

“HIDDEN CABLE SYSTEMS” google sheet above has been updated along with some of the new swath of bar/stem options
Screen Shot 2024-03-15 at 10.31.34 AM

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I’m keeping on the sidelines for this trend, but that Wolftooth headset is the best looking option going. The low stack makes all the difference.

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New Fork
The all new EXS FK-00 fork has been added to the HIDDEN CABLE SYSTEMS link above! This fork introduces a third method for internal routing 1 1/4" D Shaped so I thought it warranted it’s own post.

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Steerer - D shaped 1 1/4" to 1 1/5" Tapered
It uniquely uses a 1 1/4" upper with a d shape. Their claim is that bumping up the diameter from 1 1/8" to 1 1/4" creates more surface area for the stem clamp and headset and makes the D shaped interface safer and stronger than 1 1/8" D shaped options.

Stem Options
There are a number of good 1 1/4" stem options available but you are somewhat limited. Both Giant and Canyon use 1 1/4" Steerers and stems on most of their drop bar bikes so availability will be good for the foreseeable future. All the 1 1/4" stems that allow for the full pass through routing have been added to the sheet.

Headtubes (requires at least a 42mm OD upper bearing)
EC44/EC44 - All the standard options you know and love.
IS42/IS52 - Steel - Columbus Spirit 1.0 or Spirit 1.2 / Titanium - Deda IS42/IS52

Headsets
This is where things get weird. Conventional wisdom tells us that IS41 and IS42 upper standards are for 1 1/8" only. HOWEVER, Both Giant and Canyon use IS42 Headtubes and 1 1/4" steerers with custom FSA IS42/31.8 Headsets.

On the ZS44/EC44 side, there is only one headset I’m aware of and it’s from the UK Brand M Part. (most ZS44 headsets use a 41mm upper bearing)

Aesthetics This is purely subjective but I think this will be the best looking full internal system available. Compared to 1 1/8" D shaped steerers like Columbus, the larger 1 1/4" steerer and spacers will be much more proportional to the headtube. Compared to Oversized Upper Bearing systems like ENVE with the 44mm wide (profile view) headset spacers, it’ll be a huge improvement. (speaking purely about aesthetics)

Holler with questions!

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Just in case need other references about fork

Justin from Speeder Cycling have bunch of great fork, great build quality, ISO test, 2 years warranty, and reasonable price point. I’ve use their fork for all my base/default build.

Also seen their fork in some builder/brands bike such as Triton, TrueLove, and Stinner.