FSA ACR & SMR conversion: stem, headset and impressions
02.05.25 07:20 15.1792025-05-02T07:20:00+02:00Text: NoPain (translated by AI)Photos: Erwin HaidenWith a handlebar, stem and headset costing around 130 euros, we convert a Merida Silex to fully integrated cable routing – including installation tips and our real-world verdict.02.05.25 07:20 15.2292025-05-02T07:20:00+02:00FSA ACR & SMR conversion: stem, headset and impressions
02.05.25 07:20 15.2292025-05-02T07:20:00+02:00 NoPain (translated by AI) Erwin HaidenWith a handlebar, stem and headset costing around 130 euros, we convert a Merida Silex to fully integrated cable routing – including installation tips and our real-world verdict.02.05.25 07:20 15.2292025-05-02T07:20:00+02:00
For several years, FSA has been offering innovative solutions for internal cable routing under the names SMR (Smart Cable Routing) and ACR (Aerodynamic Cable Routing). In these systems, cables and lines are routed fully or semi-internally from the cockpit into the frame.
Although these solutions were primarily developed for OEM partners and custom frame manufacturers, other brands have also adopted these open standards—even if they do not install FSA products as standard.
An example of this is Merida with the current Silex, which, thanks to the installed headset dimensions (Acros ICR Merida External IS52/28.6/ICR/IPS - IS52/40/IPS), is compatible with all FSA ACR/SMR cockpits.
We took advantage of the opportunity and ordered the necessary parts to make our Silex sleeker and faster.
ACR (Aerodynamic Cable Routing)
The ACR system from FSA is an innovative, patent-pending cable management system that routes all cables, wires, and lines completely internally from the handlebar through the stem and headset into the frame.
The open ACR standard provides frame manufacturers with a technically advanced and cost-effective plug-in solution for clean and simple cable routing.
By using proven headset dimensions, the frame's stability remains unchanged, and thanks to the internal cable routing through the headset, the steering column retains its round cross-section.
SMR (Smart Cable Routing)
The SMR system follows the same principle as the ACR but additionally offers semi-integrated cable routing options. In this system, the cables mostly run underneath the stem and are held in place by an adjustable SMR cover.
This provides a sleek, aerodynamic look and allows for cable routing without needing to remove the stem – a major advantage when packing the bike in a case or changing the stem length.
The system is compatible with electronic and mechanical drivetrains as well as hydraulic and mechanical brakes, making it one of the most versatile cable routing solutions on the market.
From Zero to Hero
For our conversion, we only needed the stem and two headset components costing around 18 euros, which, however, were not promptly available individually. Therefore, we decided to order the entire headset. The handlebar – our fantastic FSA K-WING AGX Carbon – was already ACR-compatible and featured all the necessary openings for fully integrated cable routing.
FSA K-Wing AGX Carbon Handlebar in 440 mm
FSA's revised flagship road bike handlebar is now fully compatible with the Aerodynamic Integrated Cable Routing (ACR) and Semi-Integrated Cable Routing systems. This means that all cables can either be routed fully or partially internally, while still retaining the option for external routing.
In addition to improved ergonomics for gravel riding with a short reach and outward-flared handlebar drops, the full carbon handlebar is also said to feature a structurally reinforced clamping area. This not only makes it resistant to the higher forces of disciplines like adventure, gravel, and cyclocross but also compatible with the in-house vibration-damped stem.
FSA SMR-II O-Fork 31.8 mm bicycle stem
The FSA SMR-II O-Fork stem is an elegant and versatile solution for 31.8 mm handlebars, offering a precise fit and high stiffness. Price: 60 euros online.
Technical data:
Clamp diameter: 31.8 mm
Length: 80 mm
Angle: -10°
Material: Forged and CNC-machined aluminum with black anodized finish
Scope of delivery:
• Spacers in various heights
• SMR cover for semi-integrated cable routing
• SMR-to-ACR adapter, in case the SMR stem is to be mounted with an ACR handlebar and headset for fully integrated cable routing.
FSA No.55R 1.5" /ACR/STD headset for tapered steerer tubes - IS52/28.6 | IS52/40
Innovative, fully integrated aluminum headset for 1 1/8'' to 1.5'' tapered forks with top cover and high-quality aluminum fork crown race. An ACR-compatible frame is required for use. Cost: 51 euros online.
Dimensions
• For 1.5" head tubes with internal/external: 52/56 mm
• Upper bearing 1 1/8 inch - 36°/45° ACB (Cane Creek standard)
• Lower bearing 1.5 inch - angular contact bearing.
Note: Alternatively, the two parts FSA No.55R 11.5/ACR/STD H2473 for 7 euros and the FSA ACR H2474 compression ring for 11 euros are sufficient.
Assembly
The conversion was child's play. After I removed the crushed olives with the Dremel – because I didn’t want to shorten the cables –, I was able to disassemble the handlebar, stem, and headset without any problems and gradually replace them with the new parts.
All ACR/SMR components made a well-thought-out impression – both in terms of functionality and practicality. From the headset package, we only needed the upper aluminum compression ring (H2474), through which the cables were routed, as well as the headset spacer (H2473) made of plastic.
This was followed by a 1 cm high, two-piece spacer as well as the slim SMR-to-ACR adapter– both included in the stem's delivery package.
Stem installed, handlebars attached, cables threaded, connected, bled – done.
Verdict
| FSA ACR/SMR components | |
|---|---|
| Model year: | 2024 |
| + | Full or semi-integration |
| + | Clean look |
| + | Aerodynamic benefits |
| + | Precise adjustability |
| + | Fully practical for everyday use (stiffness & steering range) |
| + | Easy maintenance |
| + | Value for money |
| BB verdict: | Affordable upgrade for fully integrating all cables and hoses on compatible frames. |
| Rating | 9 out of 10 |
The FSA ACR/SMR components used here keep the cockpit tidy and hide every cable from the wind. Did the setup actually make me faster? Honestly, I couldn't care less. What mattered to me first and foremost was the modern, clean look – and it delivers.
The conversion was surprisingly straightforward, and the parts impressed with their well-considered design. Every individual component is perfectly matched to the others – with precisely positioned holes and pins ensuring that everything from the compression ring to the stem fits together without twisting. Once installed correctly, the handlebar remains perfectly aligned, with no spacer putting up a fight or slipping out of line.
Another genuine highlight is the unrestricted steering range in both directions. Thanks to the well-designed routing, there is no tension whatsoever from cables or housings – allowing the front wheel to turn more smoothly than ever before.
Compared with other fully integrated aftermarket solutions, the FSA system also scores with its comprehensive package, the general availability of individual parts and its unbeatable price. From me, it gets an unequivocal recommendation.
