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AProto Bike

Low Stack Internal Cable Routing Headset Adapter / Dustcover for Vision / FSA Stems & Spacers |

Low Stack Internal Cable Routing Headset Adapter / Dustcover for Vision / FSA Stems & Spacers |

Regular price $37.99 USD
Regular price Sale price $37.99 USD
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Frame and Bearing Fitment
Compression Ring

Why do you want it?

You operate a bike with electronic shifting and hydraulic braking and are seeking a lower-stack solution that can get you as low as 4-5mm from the frame. You want to use OEM internals, commonly available stems, and FSA ACR / SMR split spacers.

You are looking for a system that can pass hydraulic couplers or hose nuts through the headset for easier maintenance.

What is it?

This system must be used with a Deda DCR compression ring (available for purchase via this listing) in the following frame fitments:

1. -4mm recessed bearing / 4mm-5mm stack
2. -3/5mm recessed bearing / 5mm stack
3. -2.5mm recessed bearing / 6mm stack
4. -2mm recessed bearing / 7mm stack
5. flush bearing / 8-9mm stack
6. +1mm exposed IS bearing / 9mm stack
7. +2mm exposed IS bearing / 10-11mm stack

And bearing fitments
- A 36-degree version to fit 36x45 ~40mm ID / ~52mm OD, 36x36 (e.g., FSA ACR), ~40mm ID / ~51mm OD (e.g., Trek Emonda ALR, Trek Domane Gen IV) or ec44/40 headset bearings
- A 45-degree version to fit 45x45 ~40mm ID / ~52mm OD (e.g., Deda DCR) headset bearings

You can also purchase any of the above items with the 36 or 45 deg Deda compression ring needed to fit your bike / headset. If you wish to purchase these on your own from Deda or have them the part numbers are 36 degree: HDCOMPRACR and 45 degree: HDCOMPRDCR

Please round up the nearest recess measurement for the proper configuration and select a bearing fitment. Feel free to message me regarding additional customization or to clarify fit with your bike.

Custom frame fitments and stack can also be accommodated.

As depicted in the second image, FSA ACR / SMR split spacers can be utilized with the ACR Cover version of this system system. Please note that these are not included.

The third photo demonstrates that the dust cover is also compatible with the stock FSA adapters, as shown with the SMR adapter. These are also not included.

If you wish to purchase my version of these FSA ACR or SMR internal routing adapters that pass hose nuts and hydraulic couplers, those products are listed here:

Low Stack hose tray kits for partially external use with the FSA / Vision SMR stems are available here: and

Adapters for the Kalloy Uno stems are available here:

Adapter kits for the Specialized Tarmac SL7 / SL8 stem are available here:

Custom frame fitments, use of other compression rings, and stack measurements can also be accommodated via the custom option.

Please message me to discuss options to fit other stems or integrated routing systems.

How is it Made?

These parts are printed in the USA on Commercial Grade HP Multi-Jet Fusion machines. Parts, like these, designed to hold preload are made using PA12GB. While this material costs over 2x more than traditional PA12 Nylon, the addition of the glass increases its strength under compression by 80% and in this application, eliminates creep. Given that SLS and MJF printed nylons are only 60%-70% of the density of the high-pressure injection-molded parts made by OEMs, this assures OEM level performance.

This part must be properly installed and the headset preloaded to manufacturer specifications.

Stems, bikes, etc. not included.

Note: Items are produced when ordered and have a 4-10 day lead time. Custom orders may take up to 4 weeks depending on the sourcing of parts needed to complete the design.

Customer Reviews

Based on 1 review
Custom is where it’s at!

Had an unconventional pairing of frame / stem / cable routing and AP made it reality. Looks great and works perfectly.

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